On Mon, May 18, 2026 at 12:27 PM Robert Armstrong <[email protected]> wrote:

> > Warner Losh <[email protected]> wrote:
> > https://github.com/bsdimp/rainbow100.git has my efforts ...
>
>   Thanks, Warner!  A couple of things - #1 my Rainbow actually turns out
> to be a 100B after all.  I just assumed it was the A model, but on closer
> inspection I'm wrong.  It's a 100B2 and even has the hard disk boot option
> ("W") on the menu.  Doesn't work, of course - it just complains that the
> drive is not ready.  So this machine could support the DEC hard drive
> controller, but apparently whoever bought it originally didn't want that.
>
>   I notice that your github has a UNIV211.BIN and a PATCH.211, where as my
> Univation diskette has UNIV205 and PATCH.205.  Is that by any chance the
> MSDOS version?  V2.05 or v2.11?   Since I have a 100B I should be able to
> run MSDOS 3.11 if I can find a copy of the Rainbow version; do you know if
> there was ever a UNIV311.BIN, etc?
>

Yes. That's the MSDOS version. I don't have the 2.05 version. PATCH.211
reads part of MSDOS off the disk (directly, since it knows it has to be in
specific spots forced by the rainbow's boot loader), then places
UNIV211.BIN into the image and writes it back out. As near as I can work
out, this replaces MSDOS' drive table (effectively the DEC hardisk driver
and linked list of driver blocks) with univation's.

I've never seen a 3.11 version. One could likely adapt the assembler I did
(since it assembles to the same thing) and do the porting / work out the
math on the patch.  Since I never had working hardware, I never did that.


>   Univation did a nice job on the modification.  The half height hard
> drive and an auxiliary daughter card (which I assume is the SASI to MFM
> adapter you mentioned) fit nicely in an all around metal enclosure the size
> of a full height drive.  The drive itself is 20Mb and I wonder if it's a
> plain old ST-225, but I haven't tried to disassemble the enclosure yet to
> find out.  It's still working, so I'm reluctant to mess with it.
>

Almost certainly a plain ST-225.... Mine was. I had to recover it with the
mfm emulator...


>   If you can put up the scans of your manuals somewhere, I'd appreciate
> it.  And thanks again!
>

I'll find it and upload it or I'll scan it again.  I'll see if I can rustle
up the kicab files I started on a million years ago when I was trying to
troubleshoot my card.

Warner

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