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Digital Equipment Corporation

The Rainbow 100 had a proprietary floppy drive format. Disks formatted for the Rainbow 100 could not be read or written to by other PC computers, even though materially they were the same type of 5'' disk.

Chris Ryan reports:

There were two versions : the model 100 and the model 100+. The 100 had 64 KB soldered RAM and the 100+ had 128KB with a socket expansion for an other option board.

The system was triple boot (in BIOS, and could be set for automatic default boot preference on 100+) and booted in either CP/M, DOS, or VT100 mode.
When booted in DOS, the Z-80 acted as an I/O co-processor for the 8088 side, and visa-versa for CP/M mode.
The 8088 could also be upgraded with an NEC V-20 chip, but it involved either doing an E-PROM hack (published) or manually selecting the boot mode each time. (It was due to the V-20 being so much faster, and the post used a step/increment timing sequence, the system would respond faster than the number of clock cycles it was told to wait until looking for a response.)

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I Have rainbow software i see people are looking for

Sunday 15th May 2016
Manny (Usa)

Suitable Solutions sold not only the 286 accelerator boards and clock chips but also DOS3.10 AND the adaptation kits for Windows/286 and later Windows 3.0. You could run MS-Excel (which was a poorer number-cruncher than 1-2-3 but did offer better publication graphing). Suitable Solutions also sold the I-Drive- external DS/DD IBM format drive. $I''m reminded of this as I inventory my Rainbow equipment for eventual ebay-ing or other sale)

Sunday 16th December 2012
Brian Richards (USA)

I have a fondness for the Rainbow 100 because it was how I started my software business back in 1983 (after selling a beautiful ''67 SS 350 Camaro to buy the Rainbow. I still have the very first DEC Rainbow sold by Computerland in the San Fernando Valley.

I originally wrote a formatting program for the Rainbow, and later wrote Media Master, a disk-to-disk format conversion program. That work in the floppy disk controller world eventually led to the creation of the Fastback Plus backup programs for the Mac and PC.

Dan Pleasant brought Code Blue to me to market while he was working at HP back in the day. He later was a major contributor to Fastback for the Mac. If you guys are interested, there is some history posted at the homepage URL.

For those trying to figure out direct screen I/O, I would say it is extremely difficult. I poked around the BIOS back then to try to help my friend Dave Grenewetski (later the CEO of Mindscape) figure out how he might port his graphics program on the Osborne to the Rainbow. I don''t remember the exact reason why now, but I do know I concluded it was more work than the market size merited.

Saturday 18th December 2010
Mark Graybill (United States)
Intersecting Concepts


MANUFACTURER  Digital Equipment Corporation
TYPE  Professional Computer
YEAR  1984
KEYBOARD  Full-stroke keyboard with function keys, editing keypad and numeric keypad.
CPU  Intel 8088 + Zilog Z80 A
SPEED  4.81 MHz (8088) / 4 MHz (Z80)
RAM  64 KB (up to 896 KB)
ROM  24 KB (includes self-diagnostics)
TEXT MODES  40 x 24 / 80 x 24 / 132 x 24
GRAPHIC MODES  320 x 200 / 640 x 200 / 800 x 240
COLORS  16 among 4096 (optional)
SOUND  Beeper
SIZE / WEIGHT  48.3 (W) x 36.3 (D) x 16.5 (H) cm (system unit)
I/O PORTS  2 x RS-232, keyboard, monitor
BUILT IN MEDIA  Two 400 KB 5.25'' disk-drives
OS  MS DOS + CP/M (+ CP/M 86 - Prologue )
POWER SUPPLY  Built-in switching power supply unit
PERIPHERALS  3 expansion slots
PRICE  £2300 (U.K., 1984)

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Ready prompt
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