Galaksija
Encyclopedia
The Galaksija was originally a build-it-yourself computer
designed by Voja Antonić
. It was featured in the special edition Računari u vašoj kući (Computers in your home, written by Dejan Ristanović
) of a popular eponymous science magazine, published late December 1983 in Belgrade
, Yugoslavia. Kits were available but not required as it could be built entirely out of standard off-the-shelf parts. It was later also available in complete form.
were nearing average monthly salaries. This meant that regardless of demand for home computers, only a relative minority of people owned one - mostly a ZX Spectrum
or a Commodore 64
.
According to his own words, some time in 1983, Voja Antonić
, while vacationing in Hotel Teuta in Risan
, was reading the application handbook for the RCA CDP1802 CPU
and stumbled upon CPU-assisted video generation. Since the CDP1802 was very primitive, he decided that a Zilog
Z80 processor could perform the task as well.
Before he returned home to Belgrade
, he already had the conceptual diagrams of a computer
that used software to generate a video
picture. Although using software as opposed to hardware would significantly reduce his design's performance, it also simplified the hardware and reduced its cost.
His next step was to find a magazine to publish the diagrams in. The obvious choice was SAM Magazine published in Zagreb
, but due to prior bad experiences he decided to publish elsewhere.
The popular science magazine Galaksija appeared incompatible but he heard that they were working on a special issue dedicated to computers. He proposed publishing entire do-it-yourself diagrams, instructions, etc. to the author of the issue, Dejan Ristanović
. Everything made its way into the special issue called Računari u vašoj kući. It was released late December 1983, although it was dated January 1984.
They tried to guess the number of Galaksijas that would be built by readers. Their estimates ranged from a hundred to a thousand (a number that sounded so optimistic it provoked laughter). The actual number built by known "do-it-yourselfers" - was around 8000! This number may in reality be greater if people who did not purchase any kits (including PCB
and ROMs
) are accounted for.
Components were provided by various manufacturers and suppliers:
Later, Institute for school books and teaching aids together with Elektronika Inženjering started mass commercial production of Galaksija computers, mainly to be delivered to schools.
great descriptions. It was a great learning tool. Making a computer yourself boosts confidence and brings on the challenges of making the best out of it.
The Galaksija computer's popularity was significant enough that it became commercially available. Many educational institutions were given some. Although many of them were not ready for the experience, many others used it as a great tool to teach computer science (computer architecture and programming) even in elementary schools (in 1984!).
is a BASIC
interpreter
originally partly based on code taken from TRS-80
Level 1 BASIC, which creator believed to have been a Microsoft BASIC
. However, after extensive modifications to include video generation code (as the CPU was a major participant to reduce the cost of hardware) and improve the programming language
, what remained from the original is said to be mainly flow-control
and floating point
code. It was fully contained in 4 KB
ROM "A" or "1". Additional ROM "B" or "2" provided more Galaksija BASIC commands, assembler, monitor, etc.
was commonly referred to as "ROM 1" or just "ROM". ROM "A" contained bootstrap
code of Galaksija, its control code (rudimentary operating system
), video
generation code (as Galaksija did not have advanced video subsystem its Z80 CPU was responsible even for generating video signal) and Galaksija BASIC
.
Fitting all this functionality in 4 KB of 2732 EPROM
required a lot of effort and some sacrifices. For example, some message text areas were also used actual code (e.g. "READY" message) and the number of error messages was reduced to only two ("WHAT?" and "HOW?").
"B" of home computer
Galaksija is a 2732 EPROM
chip
that contains extensions to original Galaksija BASIC
available in computer's base ROM ("A"). It was labeled as "B" by the creator of Galaksija, Voja Antonić
, but was commonly referred to as "ROM 2".
ROM "B" contained added Galaksija BASIC commands and functions (mostly trigonometric
) as well as Z80 assembler and machine code monitor
. This ROM was not required and was an optional upgrade. Although planned on the mainboard, the content of ROM "B" was not automatically initialized during booting
. Instead, users had to execute a Galaksija BASIC command to run a machine code
program from ROM "B" before they can gain additional features. This also meant that even Galaksijas with ROM "B" plugged in can behave entirely as base models.
of home computer
Galaksija is a 2716 EPROM
chip
that contains graphical definitions of Galaksija's character set. It had no special name and was labeled "2716" after the type of 2 KB EPROM needed.
Galaksija had a slightly modified (localized) ASCII
character set:
Each character was represented as 8x13 matrix of pixel
s. In this ROM
, 8-pixel rows of each character are represented as 8 bit
s of one byte
.
. Galaksija's CPU would write one byte
to the shift register, which would, in turn, serialize its 8 bits one by one to the video output.
Since Galaksija had little RAM
, a portion of it was taken not to store information for each pixel
separately but character codes. CPU then had to look up character definitions in its character definitions ROM to find the values to send to the shift register.
This was standard operation available in Galaksija's ROM. Some software, however, reportedly took the responsibility for driving the shift register (and thus generating video) and was able to use various tricks to achieve what appears as high-resolution graphics, such as with user defined graphic characters.
It was thus possible for Galaksija with sufficient RAM upgrade (having at least 6144 bytes available for video memory) to achieve 256x208 graphics without any specialized circuitry. Other resolutions were also possible while maintaining only pixel width, by changing the amount of the active area of video picture and/or handling two interlaced video fields separately. Changing the number of active lines would have also altered the CPU usage for video generation and ratio of it available for other use.
used to connect the computer to a cassette tape recorder. Tape interface circuitry was rudimentary - other than few elements controlling the levels it was essentially one-bit digital equivalent to the one in the ZX Spectrum
. The input signal was routed to the integrated circuit
otherwise responsible for keyboard, so the CPU would "see" the input signal as a series of very fast key presses of varying lengths and gaps between them.
It is normally stated that original Galaksija does not have any dedicated (separate) audio ports and most of the programs were written as silent. It was, however, possible to utilize the cassette tape port as an audio output as well like it is done in ZX Spectrum
(its "EAR" connector). The only technical difference between ZX Spectrum and Galaksija in regards to existence of audio is that ZX Spectrum has a built-in beeper, while Galaksija's plans do not include any kind of a speaker.
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
designed by Voja Antonić
Voja Antonic
Voja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
. It was featured in the special edition Računari u vašoj kući (Computers in your home, written by Dejan Ristanović
Dejan Ristanovic
Dejan Ristanović , is a well known Serbian writer and computer publicist.In January 1981 he wrote the first article on personal computers for the popular science magazine Galaksija...
) of a popular eponymous science magazine, published late December 1983 in Belgrade
Belgrade
Belgrade is the capital and largest city of Serbia. It is located at the confluence of the Sava and Danube rivers, where the Pannonian Plain meets the Balkans. According to official results of Census 2011, the city has a population of 1,639,121. It is one of the 15 largest cities in Europe...
, Yugoslavia. Kits were available but not required as it could be built entirely out of standard off-the-shelf parts. It was later also available in complete form.
History
In the early eighties, various laws in Yugoslavia prevented importing computers into the country. At the same time, even the cheapest computers available in the WestWestern world
The Western world, also known as the West and the Occident , is a term referring to the countries of Western Europe , the countries of the Americas, as well all countries of Northern and Central Europe, Australia and New Zealand...
were nearing average monthly salaries. This meant that regardless of demand for home computers, only a relative minority of people owned one - mostly a ZX Spectrum
ZX Spectrum
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...
or a Commodore 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...
.
According to his own words, some time in 1983, Voja Antonić
Voja Antonic
Voja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
, while vacationing in Hotel Teuta in Risan
Risan
Risan is a town in the Bay of Kotor, Montenegro...
, was reading the application handbook for the RCA CDP1802 CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
and stumbled upon CPU-assisted video generation. Since the CDP1802 was very primitive, he decided that a Zilog
Zilog
Zilog, Inc., previously known as ZiLOG , is a manufacturer of 8-bit and 24-bit microcontrollers, and is most famous for its Intel 8080-compatible Z80 series.-History:...
Z80 processor could perform the task as well.
Before he returned home to Belgrade
Belgrade
Belgrade is the capital and largest city of Serbia. It is located at the confluence of the Sava and Danube rivers, where the Pannonian Plain meets the Balkans. According to official results of Census 2011, the city has a population of 1,639,121. It is one of the 15 largest cities in Europe...
, he already had the conceptual diagrams of a computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
that used software to generate a video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
picture. Although using software as opposed to hardware would significantly reduce his design's performance, it also simplified the hardware and reduced its cost.
His next step was to find a magazine to publish the diagrams in. The obvious choice was SAM Magazine published in Zagreb
Zagreb
Zagreb is the capital and the largest city of the Republic of Croatia. It is in the northwest of the country, along the Sava river, at the southern slopes of the Medvednica mountain. Zagreb lies at an elevation of approximately above sea level. According to the last official census, Zagreb's city...
, but due to prior bad experiences he decided to publish elsewhere.
The popular science magazine Galaksija appeared incompatible but he heard that they were working on a special issue dedicated to computers. He proposed publishing entire do-it-yourself diagrams, instructions, etc. to the author of the issue, Dejan Ristanović
Dejan Ristanovic
Dejan Ristanović , is a well known Serbian writer and computer publicist.In January 1981 he wrote the first article on personal computers for the popular science magazine Galaksija...
. Everything made its way into the special issue called Računari u vašoj kući. It was released late December 1983, although it was dated January 1984.
They tried to guess the number of Galaksijas that would be built by readers. Their estimates ranged from a hundred to a thousand (a number that sounded so optimistic it provoked laughter). The actual number built by known "do-it-yourselfers" - was around 8000! This number may in reality be greater if people who did not purchase any kits (including PCB
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
and ROMs
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
) are accounted for.
Components were provided by various manufacturers and suppliers:
- MIPROMIPROMIPRO Electronics Co. Ltd. , established in 1995, is an ISO-9001 certified Taiwan-based company that designs and manufactures wireless microphones, portable wireless public address and other wireless audio equipment for consumer, professional and commercial applications. U.S...
and Elektronika from BujeBujeBuje is a town situated in Istria, Croatia's westernmost peninsula, population 2,979 .Buje was known as the "sentinel of Istria" for its hilltop site located inland from the Adriatic sea. It still commands an excellent panorama. Buje has a rich history; traces of life in the region date back to...
, together with Institut za elektroniku i vakuumsku tehniku (en.English languageEnglish is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
Institute for electronics and vacuum technology) delivered PCBs, keyboardsComputer keyboardIn computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
and masks, - Mikrotehnika from GrazGrazThe more recent population figures do not give the whole picture as only people with principal residence status are counted and people with secondary residence status are not. Most of the people with secondary residence status in Graz are students...
sent integrated circuitIntegrated circuitAn integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
s - Voja AntonićVoja AntonicVoja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
personally programmed all EPROMEPROMAn EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...
s - Galaksija (magazine) collected requisition forms and organized deliveries
Later, Institute for school books and teaching aids together with Elektronika Inženjering started mass commercial production of Galaksija computers, mainly to be delivered to schools.
Impact
Galaksija was almost not comparable by any measure of features to the commercially available computers at the time. However, that was not important. The computer sparked the minds of many people. Many enthusiasts have learned how computers actually work by looking at Galaksija's schematic diagrams and Voja'sVoja Antonic
Voja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
great descriptions. It was a great learning tool. Making a computer yourself boosts confidence and brings on the challenges of making the best out of it.
The Galaksija computer's popularity was significant enough that it became commercially available. Many educational institutions were given some. Although many of them were not ready for the experience, many others used it as a great tool to teach computer science (computer architecture and programming) even in elementary schools (in 1984!).
Technical specifications
- CPUCentral processing unitThe central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
: ZilogZilogZilog, Inc., previously known as ZiLOG , is a manufacturer of 8-bit and 24-bit microcontrollers, and is most famous for its Intel 8080-compatible Z80 series.-History:...
Z80A 3.072 MHz - ROM "A" or "1" - 4 KB (2732 EPROMEPROMAn EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...
) contains bootstrap, core control and Galaksija BASICGalaksija BASICGalaksija BASIC was the BASIC interpreter of the Galaksija build-it-yourself home computer from Yugoslavia. While being partially based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC, the extensive modifications of Galaksija BASIC—such as to...
interpreter code - ROM "B" or "2" - 4 KB (optional, also 2732 EPROM) - additional Galaksija BASIC commands, assembler, machine code monitorMachine code monitorA machine code monitor is software built into or separately available for various computers, allowing the user to enter commands to view and change memory locations on the machine, with options to load and save memory contents from/to secondary storage.Machine code monitors became something of a...
, etc. - Character ROM - 2 KB (2716 EPROM) contains character definitions
- RAM: 2 to 6 KB of 6116 static RAM in base model, expandable to 54 KBKilobyteThe kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
- Text modeText modeText mode is a kind of computer display mode in which the content of the screen is internally represented in terms of characters rather than individual pixels. Typically, the screen consists of a uniform rectangular grid of character cells, each of which contains one of the characters of a...
only: 32 x 16 characters, monochromeMonochromeMonochrome describes paintings, drawings, design, or photographs in one color or shades of one color. A monochromatic object or image has colors in shades of limited colors or hues. Images using only shades of grey are called grayscale or black-and-white... - Pseudographics: 2x3 dot matrixDot matrixA dot matrix is a 2-dimensional array of LED used to represent characters, symbols and images.Typically the dot matrix is used in older computer printers and many digital display devices. In printers, the dots are usually the darkened areas of the paper...
combinations in graphic character subset - 64x48 dots total. More was done using tricks - see video generation. - SoundSoundSound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
: None according to specifications, but tape interface was occasionally used as audio output port - like the "EAR" port on ZX SpectrumZX SpectrumThe ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...
can be used both as audio and cassette port. See cassette port for details. - Storage media: cassette tape, recording at 280 bit/sBit rateIn telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
rate - I/O ports: 44-pin edge connectorEdge connectorAn edge connector is the portion of a printed circuit board consisting of traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a single discrete female connector , and they also tend to be...
with Z80 Bus, tape (DIN connectorDIN connectorA DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...
), monochrome video out (PALPALPAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
timings, DIN connectorDIN connectorA DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...
), and UHFUltra high frequencyUltra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
TV out (RCA connectorRCA connectorAn RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals...
)
BASIC ROMs
Galaksija BASICGalaksija BASIC
Galaksija BASIC was the BASIC interpreter of the Galaksija build-it-yourself home computer from Yugoslavia. While being partially based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC, the extensive modifications of Galaksija BASIC—such as to...
is a BASIC
BASIC
BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
interpreter
Interpreter (computing)
In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language...
originally partly based on code taken from TRS-80
TRS-80
TRS-80 was Tandy Corporation's desktop microcomputer model line, sold through Tandy's Radio Shack stores in the late 1970s and early 1980s. The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with...
Level 1 BASIC, which creator believed to have been a Microsoft BASIC
Microsoft BASIC
Microsoft BASIC was the foundation product of the Microsoft company. It first appeared in 1975 as Altair BASIC, which was the first BASIC, and the first high level programming language available for the MITS Altair 8800 hobbyist microcomputer....
. However, after extensive modifications to include video generation code (as the CPU was a major participant to reduce the cost of hardware) and improve the programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
, what remained from the original is said to be mainly flow-control
Control flow
In computer science, control flow refers to the order in which the individual statements, instructions, or function calls of an imperative or a declarative program are executed or evaluated....
and floating point
Floating point
In computing, floating point describes a method of representing real numbers in a way that can support a wide range of values. Numbers are, in general, represented approximately to a fixed number of significant digits and scaled using an exponent. The base for the scaling is normally 2, 10 or 16...
code. It was fully contained in 4 KB
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
ROM "A" or "1". Additional ROM "B" or "2" provided more Galaksija BASIC commands, assembler, monitor, etc.
ROM "A"
The chip labeled as "A" by the creator of Galaksija, Voja AntonićVoja Antonic
Voja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
was commonly referred to as "ROM 1" or just "ROM". ROM "A" contained bootstrap
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
code of Galaksija, its control code (rudimentary operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
), video
Video
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
generation code (as Galaksija did not have advanced video subsystem its Z80 CPU was responsible even for generating video signal) and Galaksija BASIC
Galaksija BASIC
Galaksija BASIC was the BASIC interpreter of the Galaksija build-it-yourself home computer from Yugoslavia. While being partially based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC, the extensive modifications of Galaksija BASIC—such as to...
.
Fitting all this functionality in 4 KB of 2732 EPROM
EPROM
An EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...
required a lot of effort and some sacrifices. For example, some message text areas were also used actual code (e.g. "READY" message) and the number of error messages was reduced to only two ("WHAT?" and "HOW?").
ROM "B"
ROMRead-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
"B" of home computer
Home computer
Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...
Galaksija is a 2732 EPROM
EPROM
An EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...
chip
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
that contains extensions to original Galaksija BASIC
Galaksija BASIC
Galaksija BASIC was the BASIC interpreter of the Galaksija build-it-yourself home computer from Yugoslavia. While being partially based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC, the extensive modifications of Galaksija BASIC—such as to...
available in computer's base ROM ("A"). It was labeled as "B" by the creator of Galaksija, Voja Antonić
Voja Antonic
Voja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
, but was commonly referred to as "ROM 2".
ROM "B" contained added Galaksija BASIC commands and functions (mostly trigonometric
Trigonometry
Trigonometry is a branch of mathematics that studies triangles and the relationships between their sides and the angles between these sides. Trigonometry defines the trigonometric functions, which describe those relationships and have applicability to cyclical phenomena, such as waves...
) as well as Z80 assembler and machine code monitor
Machine code monitor
A machine code monitor is software built into or separately available for various computers, allowing the user to enter commands to view and change memory locations on the machine, with options to load and save memory contents from/to secondary storage.Machine code monitors became something of a...
. This ROM was not required and was an optional upgrade. Although planned on the mainboard, the content of ROM "B" was not automatically initialized during booting
Booting
In computing, booting is a process that begins when a user turns on a computer system and prepares the computer to perform its normal operations. On modern computers, this typically involves loading and starting an operating system. The boot sequence is the initial set of operations that the...
. Instead, users had to execute a Galaksija BASIC command to run a machine code
Machine code
Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...
program from ROM "B" before they can gain additional features. This also meant that even Galaksijas with ROM "B" plugged in can behave entirely as base models.
Character ROM
Character ROMRead-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
of home computer
Home computer
Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...
Galaksija is a 2716 EPROM
EPROM
An EPROM , or erasable programmable read only memory, is a type of memory chip that retains its data when its power supply is switched off. In other words, it is non-volatile. It is an array of floating-gate transistors individually programmed by an electronic device that supplies higher voltages...
chip
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
that contains graphical definitions of Galaksija's character set. It had no special name and was labeled "2716" after the type of 2 KB EPROM needed.
Galaksija had a slightly modified (localized) ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
character set:
- There were no lowercase characters
- Codes 91 to 94 represented Serbian languageSerbian languageSerbian is a form of Serbo-Croatian, a South Slavic language, spoken by Serbs in Serbia, Bosnia and Herzegovina, Montenegro, Croatia and neighbouring countries....
characters Č, Ć, Ž and Š, respectively. Letter "Đ" was not present in original version and was commonly replaced with "DJ". - It contained 64 pseudo-graphics characters, having different combinations of dots in 2x3 matrixDot matrixA dot matrix is a 2-dimensional array of LED used to represent characters, symbols and images.Typically the dot matrix is used in older computer printers and many digital display devices. In printers, the dots are usually the darkened areas of the paper...
. - Character codes 64 and 39 are used for two halves of the logo of Elektronika Inženjering company (they can be seen in "READY" prompt)
Each character was represented as 8x13 matrix of pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
s. In this ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
, 8-pixel rows of each character are represented as 8 bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s of one byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
.
Video generation
Galaksija did not have a dedicated video circuitry. Inspired by the CDP 1802 application book, its Z80A CPU was directly responsible for modulating the monochrome video signal with a little help of a shift registerShift register
In digital circuits, a shift register is a cascade of flip flops, sharing the same clock, which has the output of any one but the last flip-flop connected to the "data" input of the next one in the chain, resulting in a circuit that shifts by one position the one-dimensional "bit array" stored in...
. Galaksija's CPU would write one byte
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
to the shift register, which would, in turn, serialize its 8 bits one by one to the video output.
Since Galaksija had little RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
, a portion of it was taken not to store information for each pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
separately but character codes. CPU then had to look up character definitions in its character definitions ROM to find the values to send to the shift register.
This was standard operation available in Galaksija's ROM. Some software, however, reportedly took the responsibility for driving the shift register (and thus generating video) and was able to use various tricks to achieve what appears as high-resolution graphics, such as with user defined graphic characters.
It was thus possible for Galaksija with sufficient RAM upgrade (having at least 6144 bytes available for video memory) to achieve 256x208 graphics without any specialized circuitry. Other resolutions were also possible while maintaining only pixel width, by changing the amount of the active area of video picture and/or handling two interlaced video fields separately. Changing the number of active lines would have also altered the CPU usage for video generation and ratio of it available for other use.
"Cassette" port
Galaksija used cassette tape as secondary storage. It featured a 5-pin DIN connectorDIN connector
A DIN connector is a connector that was originally standardized by the , the German national standards organization. There are DIN standards for a large number of different connectors, therefore the term "DIN connector" alone does not unambiguously identify any particular type of connector unless...
used to connect the computer to a cassette tape recorder. Tape interface circuitry was rudimentary - other than few elements controlling the levels it was essentially one-bit digital equivalent to the one in the ZX Spectrum
ZX Spectrum
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...
. The input signal was routed to the integrated circuit
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
otherwise responsible for keyboard, so the CPU would "see" the input signal as a series of very fast key presses of varying lengths and gaps between them.
It is normally stated that original Galaksija does not have any dedicated (separate) audio ports and most of the programs were written as silent. It was, however, possible to utilize the cassette tape port as an audio output as well like it is done in ZX Spectrum
ZX Spectrum
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd...
(its "EAR" connector). The only technical difference between ZX Spectrum and Galaksija in regards to existence of audio is that ZX Spectrum has a built-in beeper, while Galaksija's plans do not include any kind of a speaker.
Trivia
- Approximately 70% of CPU time was used just to generate videoVideoVideo is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
, which made Galaksija relatively slow in normal operation. This was unacceptable while saving or loading data from the tape so video generation was disabled during tape operations. There is also a way to disable (and re-enable) video generation from BASIC when "fast computation" is required. With video disabled, built-in BASICBASICBASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
interpreterInterpreter (computing)In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language...
was in many instances able to outperform interpreters of other home computerHome computerHome computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...
s of the time.
- Galaksija's BASICBASICBASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
has slightly different names for standard commands (e.g. BYTE instead of PEEK and POKEPEEK and POKEIn computing, PEEK is a BASIC programming language extension used for reading the contents of a memory cell at a specified address. The corresponding command to set the contents of a memory cell is POKE.-Statement syntax:...
, OLD instead of LOAD, etc.). This was done to assure that most commands begin with different letters. Not only this helps the interpreter in recognizing the command but also allowed all commands to be abbreviated to one letter followed by a dot (e.g. "P." instead of "PRINT") and, thus, take less memory for the same program, albeit with reduced readability.
- Galaksija's interpreter can report only a few error messages - "WHAT?" (used for syntax errorSyntax errorIn computer science, a syntax error refers to an error in the syntax of a sequence of characters or tokens that is intended to be written in a particular programming language....
s), "HOW?" (indicating that requested operation is theoretically impossible) and "SORRY" (errors due to system limitations). This made more ROMRead-only memoryRead-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
space available to code.
- "READY" prompt (byteByteThe byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
s in ROMRead-only memoryRead-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
representing it) is also used as code in videoVideoVideo is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
generation routineSubroutineIn computer science, a subroutine is a portion of code within a larger program that performs a specific task and is relatively independent of the remaining code....
.
- To simplify "do-it-yourself" building and reduce cost, the printed circuit boardPrinted circuit boardA printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
was designed as single-layer (one-side) board. This resulted in a relatively complicated design requiring many components-side connections to be made using wires.
- Galaksija's caseComputer caseA computer case is the enclosure that contains most of the components of a computer...
was not pre-built. Instead, the guide suggested it to be built out of the printed circuit boardPrinted circuit boardA printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
material (such as Pertinax) also used for the mainboard. Thus, the top, sides and reinforcements were solderedSolderingSoldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the workpiece...
together to form the "lid". acrylic glassAcrylic glassPoly is a transparent thermoplastic, often used as a light or shatter-resistant alternative to glass. It is sometimes called acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate...
was recommended for the underside. The guide included instructions on cleaning, painting and even decorating the assembled case. The name "GALAKSIJA" and decorative border were to be added using LetrasetLetrasetLetraset is a company based in the Kingsnorth Industrial Estate in Ashford, Kent, UK.It is known mainly for manufacturing sheets of artwork elements which can be transferred to artwork being prepared. The name Letraset was often used to refer generically to sheets of dry transferrable lettering of...
transfer letter sheets after the first (white) coat of paint but before the second coat of final colour. After the paint dried, transferred decorations were supposed to be scratched off, exposing underlying white paint.
- Among standard ways of distributing software, Galaksija programs used to be broadcast over FM RadioFM broadcastingFM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
"Beograd 202" in a show Ventilator 202Ventilator 202Ventilator 202 was a live radio show broadcast by Beograd 202 radio station during 1980s and hosted by Zoran Modli. It was one of the most important shows of Belgrade's "202" station and possibly also the most important project of its host. It first aired first June 3, 1979. Zoran Modli was its...
, hosted by Zoran ModliZoran ModliZoran Modli is a Serbian journalist, radio disc jockey and aviator. He was one of the most popular Yugoslav radio personalities, running one of the most notable radio shows of the early 1980s in Yugoslavia, Ventilator 202...
. At 280 bit/sBit rateIn telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
, a mere 2 KBKilobyteThe kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
program would take a whole minute of characteristic noise that only computer enthusiasts enjoyed.
- "Dots" of pseudographic mode were not all of the same height. They were all 3 pixels wide and 1 pixel gap existed between them (both horizontally and vertically). In one character, there were two dots horizontally and three vertically. The top and bottom dots in a character were 3 pixels tall, and the middle ones were 4 pixels tall.
- Generated video signal was made for PALPALPAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
equipment, but does not fully conform to its timings. Instead of 15,625 lines per second (625 lines 25 times per second) Galaksija generated full 16,000 because it was easier to fit in CPU timings (exactly 192 clock ticks) per line, while keeping the 25 frames (50 fieldsField (video)In video, a field is one of the many still images which are displayed sequentially to create the impression of motion on the screen. Two fields comprise one video frame...
) per second. Instead of 312.5 lines per field, this results in exactly 320 lines. Due to a missing half-line to facilitate interlacing, Galaksija's video output was essentially progressiveProgressive scanProgressive scanning is a way of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence...
, albeit because it never comes to the "second field". This did not create any usage problems as it was well within tolerance of the video equipment.
- The keyboard is laid out such that keys have their own memory-mapped addressesMemory-mapped I/OMemory-mapped I/O and port I/O are two complementary methods of performing input/output between the CPU and peripheral devices in a computer...
that, in most cases, follow the same order as ASCIIASCIIThe American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
code of the letter on the key. This saved the ROM space by reducing lookup tables but significantly increased the complexity of single-layer keyboard PCBPrinted circuit boardA printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
such that it alone required 35 jumpersJumper (computing)In electronics and particularly computing, a jumper is a short length of conductor used to close a break in or bypass part of an electrical circuit...
.
- The original Galaksija's ROM lacks support for auto-starting programs after they have been loaded from the tape (a feature common in similar computers of the time). Users had to start each program manually after the loading with a "RUN" command. This was an intentional attempt to prevent copy-protection and to encourage sharing of software between users.
See also
- Galaksija BASICGalaksija BASICGalaksija BASIC was the BASIC interpreter of the Galaksija build-it-yourself home computer from Yugoslavia. While being partially based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC, the extensive modifications of Galaksija BASIC—such as to...
- details about Galaksija's BASICBASICBASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use - the name is an acronym from Beginner's All-purpose Symbolic Instruction Code....
programming languageProgramming languageA programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely.... - Galaksija PlusGalaksija PlusGalaksija Plus was an improved version of Galaksija, with 256x208 monochrome graphics mode, 3-voice sound based on AY-3-8910 and 48 KiB RAM.The hardware of Galaksija Plus was created by Nenad Dunjić and software by Milan Tadić in 1985...
- improved version of Galaksija, announced in Jun/July 1984 (6th) issue of "Računari" magazine (in EnglishEnglish languageEnglish is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
: Computers, renamed from "Računari u vašoj kući") - Voja AntonićVoja AntonicVoja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
- the creator of Galaksija - Dejan RistanovićDejan RistanovicDejan Ristanović , is a well known Serbian writer and computer publicist.In January 1981 he wrote the first article on personal computers for the popular science magazine Galaksija...
- well known SerbianSerbsThe Serbs are a South Slavic ethnic group of the Balkans and southern Central Europe. Serbs are located mainly in Serbia, Montenegro and Bosnia and Herzegovina, and form a sizable minority in Croatia, the Republic of Macedonia and Slovenia. Likewise, Serbs are an officially recognized minority in...
writerWriterA writer is a person who produces literature, such as novels, short stories, plays, screenplays, poetry, or other literary art. Skilled writers are able to use language to portray ideas and images....
and computerComputerA computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...
publicistPublicistA publicist is a person whose job is to generate and manage publicity for a public figure, especially a celebrity, a business, or for a work such as a book, film or album...
who authored much of the special issue magazine featuring Galaksija - Z80 - Galaksija's CPU
Articles
- Computers in your home - short overview by Dejan RistanovićDejan RistanovicDejan Ristanović , is a well known Serbian writer and computer publicist.In January 1981 he wrote the first article on personal computers for the popular science magazine Galaksija...
, the author of Računari u vašoj kući magazine issue, in English languageEnglish languageEnglish is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria... - 1983: Galaksija - how it all started, by Galaksija's creator Voja AntonićVoja AntonicVoja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
himself (in Serbian languageSerbian languageSerbian is a form of Serbo-Croatian, a South Slavic language, spoken by Serbs in Serbia, Bosnia and Herzegovina, Montenegro, Croatia and neighbouring countries....
) - Computer Galaksija - detailed description of computer operation for those planning to build it, as published in the Računari u vašoj kući magazine issue. Written by creator Voja AntonićVoja AntonicVoja Antonić is a Serbian inventor, journalist and writer. He was also a magazine editor and contributed to a number of radio shows but he is best known for creating a build-it-yourself home computer Galaksija and originating a related "Build your own computer Galaksija" initiative with Dejan...
, in Serbian language. - Uputstvo za upotrebu - complete, original, user manual on-line, in Serbian language.
- Magazine Scans - scans of original magazine pages containing schematic diagrams, building and other instructions and programs for Galaksija (text in Serbian language)
- Računar Galaksija by Dejan RistanovićDejan RistanovicDejan Ristanović , is a well known Serbian writer and computer publicist.In January 1981 he wrote the first article on personal computers for the popular science magazine Galaksija...
, the author of Računari u vašoj kući magazine issue, in Serbian language
Emulators
- Galaksija Emulator - original DOSDOSDOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
-based emulatorEmulatorIn computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
by Miodrag Jevremović (in Serbian language) - Galaksija Emulator pages - Microsoft WindowsMicrosoft WindowsMicrosoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...
port of original DOSDOSDOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
emulatorEmulatorIn computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
(in Serbian language) - MESS - The open source multi-platform multi-system emulator MESSMESSMulti Emulator Super System is an emulator for many game consoles and computer systems, based on the MAME core.The primary purpose of MESS is to preserve decades of computer and console history...
supports Galaksija
Online museums
- Old-Computers.com Museum page on Galaksija
- Zgodovina - an article in Slovenian languageSlovenian languageSlovene or Slovenian is a South Slavic language spoken by approximately 2.5 million speakers worldwide, the majority of whom live in Slovenia. It is the first language of about 1.85 million people and is one of the 23 official and working languages of the European Union...
Other
- Zoran Modli Home page home page of Ventilator 202Ventilator 202Ventilator 202 was a live radio show broadcast by Beograd 202 radio station during 1980s and hosted by Zoran Modli. It was one of the most important shows of Belgrade's "202" station and possibly also the most important project of its host. It first aired first June 3, 1979. Zoran Modli was its...
radio show host (in Serbian language). Same site contains a story of Ventilator 202 show, (also in Serbian language).