The Rainbow 100 was a microcomputer produced by DEC and released in 1982. It borrowed from the VT102 for its video display and was one of the earliest dual CPU microcomputers, using a 4MHz Zilog and a 4.8 MHz Intel 8088. DEC produced three models during the production lifespan of the Rainbow; the PC-100A, PC-100B, and the 100+. It had a number of special uses, features, and add-ons as well. It was capable of running in more than one one mode for different uses; VT102 mode, 8 bit CP/M with the Zilog processor, and 16 bit CP/M or MS-DOS using the Intel chip. DEC produced an optional hard disk controller, and there were also third party products and upgrades supported by the system including third party disk controllers, a 286 processor upgrade, an adapter kit for 3.5 inch drives, and a clock chip that had a battery backup.
The Rainbows could run 8 bit CP/M, allowing users to experiment with the then new 16 bit MS-DOS, but there wasn’t a lot of DOS software available. An emulator called Code Blue was created to allow it to run IBM-PC compatible DOS software. DEC also eventually ported Windows 1.0 to the system and a modified Windows 3.0 ran with the 286 processor board. Although it was not hugely influential, it is one of the earliest commercial microcomputers.
