HP9830 memory / was Re: Still looking for Infotek MX-30 RAM

tony duell ard at p850ug1.demon.co.uk
Fri Dec 5 12:26:27 CST 2014

> > I assume you're jsut going to be plugging into the HP9830 I/O slot

> Yes. I'm considering putting the mass storage ROM on the I/O slot card
> also (similarly to how the sector buffer works), but since that ROM is
> hard-addressed, that won't actually free up the ROM slot it would
> normally occupy.

I don't really see the point. It's fairly easy to make a ROM cartridge that takes
EPROMS (IIRC 2 EPROMs, a 74x00 and a couple of transistors (to convert
the 12V selects back to 5V). Such a board (hand wired) was shown at HPCC
a couple of years ago.

If you do make your own Mass Memory ROM module, figure out  a way to 
have a switch to disable it. The Mass Memory ROM intercepts all sorts of 
BASIC commands, to the extent that DISP and PRINT (at least) fail unless there
is a working disk drive connected too. Continually plugging and unplugging the
ROM is hard on the connectors (yes, you can still get them, but desoldering
the old one is a pain).

Incidentally, the ROM module connector on the 9830 (but not on the smaller
machines) is 0.125" pitch, double sides, 18 pins on each side. Now where have 
you seen that before :-). It made finding an extender board very easy when I 
was fiddling in that area.


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