The DEC Rainbow 100B was the second model in DEC's Rainbow line of computers, following the 100A.

Like the 100A it has a dual-processor configuration, Z80 for 8-bit CP/M programs and the Intel 8088 for MS-DOS-based programs. These CPUs operate from and transfer data through a shared block of 62KB of RAM. The Rainbow's Operating System was able to detect which processor was required by examining the program diskette that was used.

There were a number of changes to the 100B. It was able to boot from a hard disk, known as the Winchester drive, due to updated firmware. This hard disk drive was optional. The machine came with 128KB of memory but had the option to expand to up to 892KB with the addition of a special adaptor board.

It was unsuccessful in the marketplace, having to compete with established brands and their IBM PC-compatible machines. CP/M compatibility was also becoming less important by this time.

The Rainbow 100+ which followed the 100B was identical to the B apart from having a hard drive installed in the computer. A 100B could therefore be upgraded to a 100+, and a 100+ was included in the upgrade package.

Manufacturer: Digital Equipment Corporation
Date: 1982

This exhibit has a reference ID of CH46273. Please quote this reference ID in any communication with the Centre for Computing History.