All Topics  
Rainbow 100

 

 
   Email Print
   Bookmark   Link
 

 

Rainbow 100
 
 
  Topics Rainbow 100 Topic Home

The Rainbow 100 was a microcomputer
Microcomputer

A microcomputer is a computer with a microprocessor as its central processing unit. Another general characteristic of these computers is that they occupy physically small amounts of space when compared to mainframe computer and minicomputers....
 introduced by Digital Equipment Corporation
Digital Equipment Corporation

Digital Equipment Corporation was a pioneering United States company in the computer industry. It is often referred to within the computing industry as DEC ....
 (DEC) in 1982 to compete in the IBM PC
IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform ....
 market. This desktop unit had the video-terminal display circuitry from the VT102, a video monitor similar to the VT220
VT220

The VT220 was a computer terminal produced by Digital Equipment Corporation from 1983 to 1987....
 in a box with both Z80
Zilog Z80

The Zilog Z80 is an 8-bit microprocessor designed and sold by Zilog from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes....
 and 8088
Intel 8088

The Intel 8088 is an Intel x86 microprocessor based on the Intel 8086, with 16-bit registers and an 8-bit external data bus. It can address up to 1 megabyte of random access memory....
 CPUs. The Rainbow 100 was a triple-boot machine: VT102 mode, CP/M
CP/M

CP/M is an operating system originally created for Intel 8080/Intel 8085 based microcomputers by Gary Kildall of Digital Research. Initially confined to single tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations, and were migrated to 16-bit processors....
 mode (using the Z80), and CP/M-86
CP/M-86

CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. The commands are those of CP/M-80....
 or MS-DOS
MS-DOS

MS-DOS is an operating system commercialized by Microsoft. It was the most commonly used member of the DOS family of operating systems and was the main operating system for personal computers during the 1980s....
 mode using the 8088.

The Rainbow came in three models, the 100A, 100B and 100+.






Discussion
Ask a question about 'Rainbow 100'
Start a new discussion about 'Rainbow 100'
Answer questions from other users
Full Discussion Forum



Encyclopedia


The Rainbow 100 was a microcomputer
Microcomputer

A microcomputer is a computer with a microprocessor as its central processing unit. Another general characteristic of these computers is that they occupy physically small amounts of space when compared to mainframe computer and minicomputers....
 introduced by Digital Equipment Corporation
Digital Equipment Corporation

Digital Equipment Corporation was a pioneering United States company in the computer industry. It is often referred to within the computing industry as DEC ....
 (DEC) in 1982 to compete in the IBM PC
IBM PC

The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform ....
 market. This desktop unit had the video-terminal display circuitry from the VT102, a video monitor similar to the VT220
VT220

The VT220 was a computer terminal produced by Digital Equipment Corporation from 1983 to 1987....
 in a box with both Z80
Zilog Z80

The Zilog Z80 is an 8-bit microprocessor designed and sold by Zilog from July 1976 onwards. It was widely used both in desktop and embedded computer designs as well as for military purposes....
 and 8088
Intel 8088

The Intel 8088 is an Intel x86 microprocessor based on the Intel 8086, with 16-bit registers and an 8-bit external data bus. It can address up to 1 megabyte of random access memory....
 CPUs. The Rainbow 100 was a triple-boot machine: VT102 mode, CP/M
CP/M

CP/M is an operating system originally created for Intel 8080/Intel 8085 based microcomputers by Gary Kildall of Digital Research. Initially confined to single tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations, and were migrated to 16-bit processors....
 mode (using the Z80), and CP/M-86
CP/M-86

CP/M-86 was a version of the CP/M operating system that Digital Research made for the Intel 8086 and Intel 8088. The commands are those of CP/M-80....
 or MS-DOS
MS-DOS

MS-DOS is an operating system commercialized by Microsoft. It was the most commonly used member of the DOS family of operating systems and was the main operating system for personal computers during the 1980s....
 mode using the 8088.

The Rainbow came in three models, the 100A, 100B and 100+. The 'A' model didn't allow for a hard disk controller, whereas the 'B' allowed this option and the '+' shipped with the controller and a hard drive. Versions of the 100A shipped outside the USA included a user changeable ROM chip in a special casing. The user changed the built in ROM for this one to support their keyboard layout and language of the boot screen. The 100B has this selection built into the boot up firmware.

The '100+' model is actually a marketing designation signifying that the system ships with a hard drive installed; the 100+ and 100B are identical in all other respects. The '100B' (and '100+' by definition) had the option to boot from the hard disk (or Winchester drive, as it appeared in the boot menu), while the '100A' firmware did not support booting directly from the hard disk.

The '100A' model shipped with 128 KB memory on the motherboard, while the '100B' had 192 KB memory on the motherboard.

The Rainbow 100 and the other two microcomputers which DEC announced at the same time (DECmate II
DECmate

DECmate was the name of a series of PDP-8-compatible computers produced by the Digital Equipment Corporation in the early 1980s. All of the models used an Intersil or Harris 6100 6120 microprocessor which emulated the 12-bit DEC PDP-8 CPU....
 and Pro-350) had two quirks that annoyed conservative users. The LK201
LK201

The LK201 was a detachable computer keyboard introduced by Digital Equipment Corporation of Maynard, Massachusetts, Massachusetts in 1982. It was first used by Digital's VT220 ANSI/ASCII terminal and was subsequently used by the Rainbow-100, DECmate#DECmate II, and Pro-350 microcomputers and many of Digital's computer workstations such as the...
 keyboard used a new layout that made some ASR33
ASR33

Introduced about 1963, Teletype Corporation's ASR33 was a very popular model of teleprinter. Designed for light-duty office use, it was much flimsier than its heavy duty cousin, the Model 35ASR....
 and VT100
VT100

VT100 is a video computer terminal which was made by Digital Equipment Corporation . It became the de facto standard used by terminal emulators....
 users unhappy. However, the VT220 style of this keyboard can clearly be seen in the layout of the enhanced 101-key keyboard
Enhanced keyboard

The enhanced keyboard is a type of computer keyboard first made by IBM which has 101 or 102 keys. The major difference between this and previous XT/AT keyboards is the twelve function keys arranged in a line across the top of the keyboard as opposed to ten grouped on the left hand side of the keyboard....
 adopted by IBM in 1987. The floppy disk drives took 400 KB single-sided quad-density disks when all the other microcomputers were using 360 KB double-sided double-density disks. Initially users had to buy media from DEC with a special reinforcing ring at the hub, but this became unnecessary when other manufacturers began producing diskettes that suited both types of drive.

Of note was the single motor used to drive both disk drives via a common spindle, which were arranged one on top of the other. That meant that one disk went underneath the first but inserted upside down. This confused many first time users, who found that the machine would not read the disk.

The Graphics Option was a user-installable module that added graphics and color display capabilities to the Rainbow system. The Graphic module was based on a NEC 7220 Graphic Display Controller (GDC) and a 8x64 K DRAM video memory.

Various Rainbow option upgrades were available from DEC including a high resolution color graphics card (driving an RGB DEC monitor), ST-506
ST-506

The ST-506 was the first 5.25 inch hard disk drive. Introduced in 1980 by Seagate Technology , it stored up to 5 megabytes after formatting. The similar 10 MB ST-412 was introduced in late 1981....
 hard drive controller and drive (typically 5, 10 or 20 MB
Megabyte

Megabyte is a SI prefix-multiple of the unit byte for digital information computer storage or transmission and is equal to 106 bytes....
), a memory expansion module expanding memory up to a maximum 896 KB, an 8087
Intel 8087

The 8087 was the first math coprocessor for 16 bit processors designed by Intel ; it was built to be paired with the Intel Intel 8088 and Intel 8086 microprocessors....
 math co-processor upgrade and a DECnet
DECnet

DECnet is a suite of network protocols created by Digital Equipment Corporation, originally released in 1975 in order to connect two PDP-11 minicomputers....
 network adapter
Network card

A network card, network adapter, network interface controller , network interface card, or LAN adapter is a computer hardware component designed to allow computers to communicate over a computer network....
.

Third party upgrades were also available including an 80286
Intel 80286

The Intel 286, introduced on February 1, 1982, was an x86 16-bit microprocessor with 134,000 transistors.It was widely used in IBM PC compatible computers during the mid 1980s to early 1990s....
 (286) processor upgrade (Turbow-286) and 3.5 inch disk adapter kit (IDrive), and a battery-backed clock chip (ClikClok), all from Suitable Solutions.

A benefit of the Rainbow was that it could continue to run 8-bit
8-bit

Eight-bit CPUs normally use an 8-bit data bus and a 16-bit address bus which means that their address space is limited to 64 KBs. This is not a "natural law", however, so there are exceptions....
 CP/M software as users moved into the 16-bit
16-bit

16-bit architectureThe HP 2100#Descendants and variants , introduced in 1975, was the world's first 16-bit microprocessor.Prominent 16-bit processors include the PDP-11, Intel 8086, Intel 80286 and the WDC 65C816....
 world of MS-DOS. The disadvantage was that little DOS software was released on Rainbow media and there were subtle differences between MS-DOS, as run on a Rainbow, and MS-DOS (or PC-DOS
PC-DOS

IBM PC DOS was a DOS operating system for the IBM Personal Computer, sold throughout the 1980s and 2000s....
) running on true IBM PC compatible
IBM PC compatible

IBM PC compatible computers are those generally similar to the original IBM Personal Computer, IBM Personal Computer XT, and IBM Personal Computer/AT....
s. Towards the end of its life, Rainbow users were able to run IBM PC compatible MS-DOS software using an emulation application called Code Blue.

Of note is that Microsoft
Microsoft

Microsoft Corporation is a multinational corporation computer technology corporation that develops, manufactures, licenses, and supports a wide range of computer software products for computing devices....
 Windows 1.0
Windows 1.0

Windows 1.0 is a 16-bit graphical operating environment that was released on 20 November 1985. It was Microsoft's first attempt to implement a Computer multitasking graphical user interface-based operating environment on the personal computer platform....
 was ported to the Rainbow by DEC. There was also a third party upgrade that included a 286 processor board and a modified version of Windows 3.0
Windows 3.0

Windows 3.0 is the third major release of Microsoft Microsoft Windows, and was released on 22 May 1990. It became the first widely successful version of Windows and a powerful rival to Macintosh and the Commodore Amiga on the GUI front....
.

External links