DEC Rainbow 100

Our first DEC Rainbow 100 was donated by Mary Christian of Spencer, Massachusetts. Our second Rainbow 100B (S/N ZG 02822) donated on 1/26/23 by an ex-DEC employee, Rob Goldstein.

The later "B" model of the Rainbow 100 could boot from a Winchester disk drive. Rob's has a 100+ badge on the front indicating that it has a disk drive disk drive installed. In this case a larger 40 MB RD52 disk is installed instead of the normal 20 MB RD31 disk. This one also has lots of options including a PC-1XX-BA color graphics video board and 13" VR-241 color monitor (S/N Y7B C2117) made in 1987 by Hitachi. It also came with the standard VR-201 monochrome monitor.

The Rainbow 100 was introduced in 1982, and had both 8-bit Zilog Z80A and 16-bit Intel 8088 CPU chips. It could run CP/M software in 8-bit mode, and MS-DOS or CP/M 86 software in 16-bit mode. Unfortunately you generally could not run MS-DOS software from an IBM PC on a Rainbow. When running the CP/M operating system it would automatically determine of the software was 8-bit or 16-bit and run it on the appropriate processor chip. A base Rainbow 100 had 64K RAM, and was upgradable to 828K. The later 100B came with 128K, and was expandable to 896K. The unusual DEC RX50 diskette drive is two drives sharing common spindle and head seek motors. It has a capacity of 400kB, and is single-sided quad-density.

The inside of the Rainbow 100 showing the RD52 disk drive.

The Rainbow 100 from Rob Goldstein came with lots of software.