Got a Rainbow 100 and ...

Tony Duell ard.p850ug1 at
Sun Nov 11 04:24:45 CST 2018

On Sun, Nov 11, 2018 at 7:41 AM Alan Perry <aperry at> wrote:
> On 11/10/18 11:00 PM, Tony Duell wrote:
> > On Sun, Nov 11, 2018 at 6:56 AM Alan Perry <aperry at> wrote:
> >>
> >>
> >> On 11/10/18 10:51 PM, Tony Duell wrote:
> >>> On Sun, Nov 11, 2018 at 6:47 AM Alan Perry via cctalk
> >>> <cctalk at> wrote:
> >>>
> >>>> What I got was the system unit, a VR201 monitor, a keyboard, a vertical
> >>>> deskside stand for the system unit, and a LQP02 daisy wheel printer. I
> >>>> also got the MS-DOS and CP/M doc and software slip cover boxes. The CP/M
> >>>> disk box is still sealed and the CP/M docs are still in shrink wrap. The
> >>>> specific need that the seller bought it for involved MS-DOS, not CP/M.
> >>> Does it have any of the optional expansion boards (hard disk controller,
> >>> RAM, graphics) in it?
> >> Right now I am looking up how to open up the system unit and see what's
> >> inside.
> > There's a catch on each side under the 'step'. Release those and the
> > cover comes off. Unplug the drive and power cables from the main
> > PCB assembly (at the rear right), undo the thumbscrews on the back
> > and the PCB assembly slides out.
> Nice.

Yes, this series of machines (Rainbow, DECmate II, Pro300) can be
dismantled into the FRUs without using tools. Not that that is a great
advantage for us now, since once you've taken it apart you most likely
need a soldering iron, 'scope, logic analyser, etc to fix it.

> It is clean on the inside. A very thin coating of dust.
> As far as the hardware itself ...
> There is nothing in the left-side drive bay, just the dual floppy drive
> in the right-side bay.
> There is a memory expansion board (how can one determine its size?) and

I seem to remember there are at least 2 versions of the RAM card. The older
one doesn't have a DIP switch on it and can only take 64K DRAMs. I've only
ever seen it with a full set of RAMs soldered in, giving an extra 192K (3 banks
of RAM).

The later one has a 4-way DIP switch on it. Each bank of RAMs (9 chips each)
can either be 64K or 256K. You have to set the switch appropriately (I think
positions 1-3 are the size of each of the 3 banks of RAM, position 4 enables/
disables parity checking).. If you have that one, it's probably easiest to see
what RAMs are installed.

> the board that the floppy drive connects to (is it all floppy controller?).

Yes. A lot of it is the data separator.

> That's it.
> Is there anything that I should check on it before I connect it to power?

Depends on how lucky you feel. I would always test the PSU on a
dummy load before connecting the boards and drive.


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