Donor: Don Miller
Location: Williamsburg, VA
Introduced in May 1982, the DEC Rainbow attempted to
bridge the gap between the Z80-based CP/M world and the
8086-based DOS world. It contained both chips and could
run either operating system. I've been told that, under
DOS, it used its own special graphics hardware, which
left a little extra conventional memory for programs. It
could also boot into a dumb terminal mode. The keyboard
is way cool, with lots of special word processing keys.
The amber monitor gets both its power and its video
signal through a single cable.
Of special note are the dual
floppy drives. There is a single drive and head
assembly which is shared by both drive slots. As a
consequence, disks in the upper slot must be inserted
upside down in relation to the lower slot. Rainbow disks
had red marks which you lined up with the marks on the
drive slots to ensure proper alignment. I would imagine
that this set-up would also prevent you from reading from
both disks at the same time.
Unfortunately, it came without disks. Rainbows used
their own special format, so if anyone has some Rainbow
disks sitting around unused, feel free to send them to
Other Z80 / 8086 hybrids include the Epson QX-16.
Motherboard - Notice the multiple
daughterboards on top.
Rainbow Guts -
The Rainbow was very easy to take apart. Flipping
two plastic switches allowed the top to just lift
off. By unscrewing four thumbscrews, visible in
this picture, and pulling off two cables, the
motherboard simply slid out of the back of the
case. The cables were labelled and even had pull
loops. In this picture the motherboard is halfway
out of the case. Floppy and hard drives slid in
and out of the front just as easily.
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