Q: What models are available?
There were two major releases of the Rainbow 100. The model numbers were 100A and 100B. The 100A was the first released. This model had less expandability than subsequent models and could not support a hard disk. Only 128KB of memory was installed on the motherboard of a 100A The 100A also contained an AC fan, making the unit louder than later releases. The 100A was produced initially in Westfield, Massachusetts, but later built in Hong Kong, where all later models were assembled.
The 100B was the first Rainbow to support booting from hard disks. The 100B also had a DC fan, making the unit run quieter than a 100A. The power supply in the 100B was beefed up to handle the high power requirements for starting hard disks. 100Bs shipped with 192KB of memory on the motherboard, and were also packaged with memory expansion boards, allowing 896Kbytes total memory. Other minor differences between the 100A and 100B exist, including ROM sizes and graphics capabilities.
The 100+ was basically a 100B with a hard disk and controller included. The computer was initially available with 5, 10, or 20 meg hard drives. 100+ normally had a plastic 100+ emblem glued to the front of the CPU unit.
There was one other model, named the Rainbow 190. Information on this system is hard to find. Apparently, Digital announced this to be a business-only PC. The 190 is basically a designation for a Rainbow 100B shipped with specialized software preloaded on the hard disk.