Rainbow 100-A © 1982 Digital Equipment Corp.
The 100-A model was the first produced by Digital. The distinguishing characteristic of the 100-A model from an end-user perspective was that the earlier firmware did not support booting from a hard disk.
Versions of the 100-A shipped outside the USA included a user-changeable ROM chip in a special casing. The user changed the built-in ROM for this one to support their keyboard layout and language of the boot screen.