Dick Smith Super-80 Computer
Encyclopedia
The Dick Smith Super-80 was a Zilog Z80
based kit computer developed as a joint venture between Electronics Australia
magazine and Dick Smith Electronics
. It was presented as a series of construction articles in Electronics Australia magazine's August, September and October 1981 issues.
Electronics Australia
had published a number of computer projects prior to the Super-80, including the EDUC-8
in 1974, the Mini Scamp and the DREAM 6800 Video Computer.
The computer was sold as a "short form" kit for AU$289.50. For this, the purchaser received the computer PCB
, an assembly manual (a copy of the construction articles from
Electronics Australia
) and basic components, including 16kB of RAM
and a 2kB EPROM
containing a machine code monitor
program. The technical manual and power transformer were sold separately, as were a kit of I.C. sockets, a BASIC
interpreter program and from mid-1982 onwards, a metal case to house the computer.
The computer proved to be a popular construction project, with an advertisement in November 1982 claiming: "Over 2000 sold."
The popularity of the Super-80 led to a small industry growing up around addressing the shortcomings of the original computer - especially the black and white, 32 x 16 character, upper case only video display.
The original name of the computer was "Nova-80", but it was changed at the last minute to avoid "possible legal ramifications".
8 bit microprocessor
. As standard, it had 16kB of dynamic RAM in the form of 8 x 4116 RAM chip. RAM could be expanded to 32kB or 48kB through the addition of rows of eight 4116 RAM chips.
The computer was assembled on a single double-sided printed circuit board. The board was supplied in a light cardboard sleeve that appeared to be an LP record sleeve, even having the words "Dick Smith Super 80 Microcomputer Kit Printed Circuit Board" and the part number "Cat H-8402" printed along the spine.
To keep the price of the computer and the component count down, a novel technique was used to implement the video display. Instead of an expensive video display controller chip with dedicated memory, the Super-80 used discreet TTL logic to implement the video display and 512 bytes of system RAM was shared between the video display and the CPU. Fifty times per second, the CPU was turned off for around 10ms by asserting the Z80 BUSREQ (DMA
) pin. The video display circuitry would then read from the shared RAM while it refreshed the image on the screen. In addition to a 50% degradation in processor performance, this meant that it was not possible to perform any accurate timing in software, since the programmer had no control over when the next video display refresh cycle would occur. The video display could be switched off under software control for greater processing speed, or when accurate software timing was required. The most common situation in which this occurred was when the built in cassette interface was being used. The location of the 512 bytes of video memory was normally at the top of the available RAM, but could be changed by writing to an I/O port.
The keyboard was part of the main computer PCB, but prior to assembly, the constructor could opt to cut the keyboard section of the printed circuit board off and connect it to the main board with ribbon cable. The keyboard was wired as an 8 x 8 matrix and connected to the computer via the two 8 bit ports of a Z80 PIO chip. Pressing the keys, and <4> at the same time generated an interrupt
that would perform a "warm start" of the monitor program. The keyboard 'read' routine supplied in ROM
was "negative edge triggered" and would block while a key was down. As a result, most action games incorporated their own keyboard driver.
The standard computer had no serial or parallel I/O as such, relying on the optional S-100 bus
interface for I/O and expansion. A 10 pin connector at the back of the board was labeled "PORT" and had power, as well as a pair of digital outputs and two available digital input lines. The connector was for a future RS-232
/ 20mA current loop
serial interface, but this was never implemented.
Mass storage was available in the form of a cassette tape interface running at 300 baud. Accessing the cassette interface required the video display to be switched off, so an LED was provided to show activity during a tape load or save operation. The LED would change state each time a 256 byte block of data was successfully transferred.
The Z80 interrupt
line was connected to the keyboard PIO and the "Non Maskable Interrupt
" line was not connected.
program in ROM.
A BASIC interpreter could be purchased either on cassette tape or on a set of three 4kB EPROMs. The first 4kB BASIC EPROM
replaced the 2kB monitor EPROM
supplied with the computer and contained the first 2kB of BASIC, plus the monitor program. The BASIC interpreter was based on Tiny BASIC rewritten and modified by Ron Harris.
In its November 1981 edition (p93), Electronics Australia announced a programming competition with the chance to win one of two dot matrix printers. EA later compiled the better programs submitted by readers into a book called "Software for the Super-80 Computer".
The El Graphix kit added the ability to display lower case characters and "chunky" graphics.
The Printer Interface was an S-100 Bus card giving the Super-80 a Centronics parallel printer port.
The VDU Expansion Board (VDUEB) was an enhanced video display board for the Super-80 developed by Microcomputer Engineering (MCE). The VDUEB gave the Super-80 an 80x25 video display with limited graphics capabilities. It was based on a 6845 CRTC I.C. and had its own 2kB of video RAM
and 2kB of character generator RAM. Installation of the VDUEB board was a one-way process, as it required major modifications to the Super-80 printed circuit board including cutting of tracks and soldering in many wire links between various parts of the board. The VDUEB was then connected via three I.C. sockets formerly occupied by the original video display circuitry. Removal of the original DMA
based video display effectively doubled the performance of the computer, since the CPU was no longer being disabled 50 times per second for video display refreshes. The board gave the Super-80 similar video display capabilities to the Applied Technology
Microbee
computer, released about six months after the Super-80. This led to many Microbee
games being ported to the VDUEB equipped Super-80. The VDUEB proved to be a popular modification, with a users' group
forming for owners of VDUEB equipped computers - The "Super-80 VDUEB Users' Club".
The Universal Floppy Disk Controller (UFDC) was an add-on floppy disk
interface developed by Microcomputer Engineering (MCE). The UFDC was based on the Western Digital
WD2793 floppy disk controller
chip and had a Z80 DMA
controller on board. The most popular disk format
was 5 1/4" (133 mm) 80 track, double sided, double density using a Mitsubishi floppy drive mechanism. This gave a formatted disk capacity of 800kB. The UFDC's use of DMA
required the VDUEB upgrade to be present. To install the disk controller, the Z80 CPU was removed from the main computer board and installed on the UFDC board. The UFDC then piggybacked on the socket vacated by the CPU. This meant that in theory, the UFDC could be used with almost any Z80 based system, provided there was enough physical space above the CPU. The UFDC used a primitive track based disk operating system
called "Super-80 DOS", however a CP/M BIOS later became available.
The MXB-1 Memory Expansion Board was designed by a member of the VDUEB Users' Club. The MXB-1 contained space for extra EPROMs, an optional battery backed real time clock, a centronics compatible printer interface and address decoding for up to 192kB of RAM. The extra RAM was installed by replacing the standard 4116 16k x 1 bit RAM chips with 4164 64k x 1 bit RAM chips. The CPU's 64kB address limit was worked around through bank switching
. The MXB-1 was mostly of benefit to users running the CP/M
disk operating system
, since CP/M
could then have a full 64kB of RAM for programs, with up to 128kB being used as a small RAM disk
.
Zilog Z80
The Zilog Z80 is an 8-bit microprocessor designed by Zilog and sold from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes...
based kit computer developed as a joint venture between Electronics Australia
Electronics Australia
Electronics Australia was Australia's longest-running general electronics magazine.It can claim to trace its history to 1922 when the Wireless Weekly magazine was formed. Its content was a mix of general and technical articles on the new topic of radio....
magazine and Dick Smith Electronics
Dick Smith Electronics
Dick Smith is an international electronics retailer, founded in 1968 by Richard "Dick" Smith. Today, it is a subsidiary of Woolworths Limited, incorporating Tandy, and the remaining Dick Smith Powerhouse Stores...
. It was presented as a series of construction articles in Electronics Australia magazine's August, September and October 1981 issues.
Electronics Australia
Electronics Australia
Electronics Australia was Australia's longest-running general electronics magazine.It can claim to trace its history to 1922 when the Wireless Weekly magazine was formed. Its content was a mix of general and technical articles on the new topic of radio....
had published a number of computer projects prior to the Super-80, including the EDUC-8
Educ-8
The EDUC-8, pronounced "educate", was an early microcomputer kit published by Electronics Australia in a series of articles starting in August 1974 and continuing to August 1975. Electronics Australia initially believed that it was the first such kit, but later discovered that Radio-Electronics had...
in 1974, the Mini Scamp and the DREAM 6800 Video Computer.
The computer was sold as a "short form" kit for AU$289.50. For this, the purchaser received the computer 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...
, an assembly manual (a copy of the construction articles from
Electronics Australia
Electronics Australia
Electronics Australia was Australia's longest-running general electronics magazine.It can claim to trace its history to 1922 when the Wireless Weekly magazine was formed. Its content was a mix of general and technical articles on the new topic of radio....
) and basic components, including 16kB of 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...
and a 2kB 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...
containing a 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...
program. The technical manual and power transformer were sold separately, as were a kit of I.C. sockets, 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 program and from mid-1982 onwards, a metal case to house the computer.
The computer proved to be a popular construction project, with an advertisement in November 1982 claiming: "Over 2000 sold."
The popularity of the Super-80 led to a small industry growing up around addressing the shortcomings of the original computer - especially the black and white, 32 x 16 character, upper case only video display.
The original name of the computer was "Nova-80", but it was changed at the last minute to avoid "possible legal ramifications".
Specifications
- CPU: Zilog Z80Zilog Z80The Zilog Z80 is an 8-bit microprocessor designed by Zilog and sold from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes...
- Clock Speed: 2 MHz
- Expansion: S-100 BusS-100 busThe S-100 bus or Altair bus, IEEE696-1983 , was an early computer bus designed in 1974 as a part of the Altair 8800, generally considered today to be the first personal computer...
Slot (Optional) - Keyboard: 60 Key
- Mass Storage: Cassette Tape (300 Baud, Kansas City StandardKansas City standardThe Kansas City Standard , or Byte standard, is a digital data format for audio cassette drives. Byte magazine sponsored a symposium in November 1975 in Kansas City, Missouri to develop a standard for storage of digital computer data on inexpensive consumer quality cassettes, at a time when...
) - RAMRam-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...
: 16kB (maximum 48kB) - 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...
: 2kB (maximum 12kB) - Sound: None
- Video Display: Monochrome, 32 x 16 Characters, Upper Case Only
Technical Description
The Super-80 was based on the Zilog Z80Zilog Z80
The Zilog Z80 is an 8-bit microprocessor designed by Zilog and sold from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes...
8 bit microprocessor
Microprocessor
A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...
. As standard, it had 16kB of dynamic RAM in the form of 8 x 4116 RAM chip. RAM could be expanded to 32kB or 48kB through the addition of rows of eight 4116 RAM chips.
The computer was assembled on a single double-sided printed circuit board. The board was supplied in a light cardboard sleeve that appeared to be an LP record sleeve, even having the words "Dick Smith Super 80 Microcomputer Kit Printed Circuit Board" and the part number "Cat H-8402" printed along the spine.
To keep the price of the computer and the component count down, a novel technique was used to implement the video display. Instead of an expensive video display controller chip with dedicated memory, the Super-80 used discreet TTL logic to implement the video display and 512 bytes of system RAM was shared between the video display and the CPU. Fifty times per second, the CPU was turned off for around 10ms by asserting the Z80 BUSREQ (DMA
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
) pin. The video display circuitry would then read from the shared RAM while it refreshed the image on the screen. In addition to a 50% degradation in processor performance, this meant that it was not possible to perform any accurate timing in software, since the programmer had no control over when the next video display refresh cycle would occur. The video display could be switched off under software control for greater processing speed, or when accurate software timing was required. The most common situation in which this occurred was when the built in cassette interface was being used. The location of the 512 bytes of video memory was normally at the top of the available RAM, but could be changed by writing to an I/O port.
The keyboard was part of the main computer PCB, but prior to assembly, the constructor could opt to cut the keyboard section of the printed circuit board off and connect it to the main board with ribbon cable. The keyboard was wired as an 8 x 8 matrix and connected to the computer via the two 8 bit ports of a Z80 PIO chip. Pressing the keys
Interrupt
In computing, an interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution....
that would perform a "warm start" of the monitor program. The keyboard 'read' routine supplied in 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...
was "negative edge triggered" and would block while a key was down. As a result, most action games incorporated their own keyboard driver.
The standard computer had no serial or parallel I/O as such, relying on the optional S-100 bus
S-100 bus
The S-100 bus or Altair bus, IEEE696-1983 , was an early computer bus designed in 1974 as a part of the Altair 8800, generally considered today to be the first personal computer...
interface for I/O and expansion. A 10 pin connector at the back of the board was labeled "PORT" and had power, as well as a pair of digital outputs and two available digital input lines. The connector was for a future RS-232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
/ 20mA current loop
Current loop
A current loop describes two different electrical signalling schemes.- Digital :For digital serial communications, a current loop is a communication interface that uses current instead of voltage for signaling...
serial interface, but this was never implemented.
Mass storage was available in the form of a cassette tape interface running at 300 baud. Accessing the cassette interface required the video display to be switched off, so an LED was provided to show activity during a tape load or save operation. The LED would change state each time a 256 byte block of data was successfully transferred.
The Z80 interrupt
Interrupt
In computing, an interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution....
line was connected to the keyboard PIO and the "Non Maskable Interrupt
Non-Maskable interrupt
A non-maskable interrupt is a computer processor interrupt that cannot be ignored by standard interrupt masking techniques in the system. It is typically used to signal attention for non-recoverable hardware errors...
" line was not connected.
Software
The Super-80 came with a 2kB machine code monitorMachine 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...
program in ROM.
A BASIC interpreter could be purchased either on cassette tape or on a set of three 4kB EPROMs. The first 4kB BASIC 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...
replaced the 2kB monitor 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...
supplied with the computer and contained the first 2kB of BASIC, plus the monitor program. The BASIC interpreter was based on Tiny BASIC rewritten and modified by Ron Harris.
In its November 1981 edition (p93), Electronics Australia announced a programming competition with the chance to win one of two dot matrix printers. EA later compiled the better programs submitted by readers into a book called "Software for the Super-80 Computer".
Accessories and Options
- B-3600 Super-80 Technical Manual
- B-3602 Super-80 BASIC Handbook
- H-3200 Metal Case
- K-3602 BASIC Interpreter on Cassette Tape
- K-3603 I.C. Socket Kit
- K-3604 BASIC Interpreter in EPROM
- K-3606 S-100 Expansion Unit
- K-3607 Lower Case Character Generator
Modifications
Many Super-80 owners chose to modify their machines to address the limitations of the original machine.The El Graphix kit added the ability to display lower case characters and "chunky" graphics.
The Printer Interface was an S-100 Bus card giving the Super-80 a Centronics parallel printer port.
The VDU Expansion Board (VDUEB) was an enhanced video display board for the Super-80 developed by Microcomputer Engineering (MCE). The VDUEB gave the Super-80 an 80x25 video display with limited graphics capabilities. It was based on a 6845 CRTC I.C. and had its own 2kB of video 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...
and 2kB of character generator RAM. Installation of the VDUEB board was a one-way process, as it required major modifications to the Super-80 printed circuit board including cutting of tracks and soldering in many wire links between various parts of the board. The VDUEB was then connected via three I.C. sockets formerly occupied by the original video display circuitry. Removal of the original DMA
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
based video display effectively doubled the performance of the computer, since the CPU was no longer being disabled 50 times per second for video display refreshes. The board gave the Super-80 similar video display capabilities to the Applied Technology
Applied Technology
Applied Technology, Australia founded by Owen Hill in 1975, was a pioneer producer of home computers that ran CP/M on Zilog Z80 microprocessors. Their MicroBee computer was the first commercial personal computer manufactured in Australia....
Microbee
MicroBee
MicroBee was a series of home computers by Applied Technology, later known as MicroBee Systems.The original MicroBee computer was designed in Australia by a team including Owen Hill and Matthew Starr...
computer, released about six months after the Super-80. This led to many Microbee
MicroBee
MicroBee was a series of home computers by Applied Technology, later known as MicroBee Systems.The original MicroBee computer was designed in Australia by a team including Owen Hill and Matthew Starr...
games being ported to the VDUEB equipped Super-80. The VDUEB proved to be a popular modification, with a users' group
Users' group
A users' group is a type of club focused on the use of a particular technology, usually computer-related....
forming for owners of VDUEB equipped computers - The "Super-80 VDUEB Users' Club".
The Universal Floppy Disk Controller (UFDC) was an add-on floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
interface developed by Microcomputer Engineering (MCE). The UFDC was based on the Western Digital
Western Digital
Western Digital Corporation is one of the largest computer hard disk drive manufacturers in the world. It has a long history in the electronics industry as an integrated circuit maker and a storage products company. Western Digital was founded on April 23, 1970 by Alvin B...
WD2793 floppy disk controller
Floppy disk controller
A floppy disk controller is a special-purpose chip and associated disk controller circuitry that directs and controls reading from and writing to a computer's floppy disk drive . This article contains concepts common to FDCs based on the NEC µPD765 and Intel 8072A or 82072A and their descendants,...
chip and had a Z80 DMA
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
controller on board. The most popular disk format
Floppy disk format
Floppy disk format and density refer to the logical and physical layout of data stored on a floppy disk. Since their introduction, there have been many popular and rare floppy disk types, densities, and formats used in computing, leading to much confusion over their differences...
was 5 1/4" (133 mm) 80 track, double sided, double density using a Mitsubishi floppy drive mechanism. This gave a formatted disk capacity of 800kB. The UFDC's use of DMA
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
required the VDUEB upgrade to be present. To install the disk controller, the Z80 CPU was removed from the main computer board and installed on the UFDC board. The UFDC then piggybacked on the socket vacated by the CPU. This meant that in theory, the UFDC could be used with almost any Z80 based system, provided there was enough physical space above the CPU. The UFDC used a primitive track based disk operating system
Disk operating system
Disk Operating System and disk operating system , most often abbreviated as DOS, refers to an operating system software used in most computers that provides the abstraction and management of secondary storage devices and the information on them...
called "Super-80 DOS", however a CP/M BIOS later became available.
The MXB-1 Memory Expansion Board was designed by a member of the VDUEB Users' Club. The MXB-1 contained space for extra EPROMs, an optional battery backed real time clock, a centronics compatible printer interface and address decoding for up to 192kB of RAM. The extra RAM was installed by replacing the standard 4116 16k x 1 bit RAM chips with 4164 64k x 1 bit RAM chips. The CPU's 64kB address limit was worked around through bank switching
Bank switching
Bank switching is a technique to increase the amount of usable memory beyond the amount directly addressable by the processor. It can be used to configure a system differently at different times; for example, a ROM required to start a system from diskette could be switched out when no longer...
. The MXB-1 was mostly of benefit to users running the CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
disk operating system
Disk operating system
Disk Operating System and disk operating system , most often abbreviated as DOS, refers to an operating system software used in most computers that provides the abstraction and management of secondary storage devices and the information on them...
, since CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
could then have a full 64kB of RAM for programs, with up to 128kB being used as a small RAM disk
RAM disk
A RAM disk or RAM drive is a block of RAM that a computer's software is treating as if the memory were a disk drive...
.