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Oh yes, this. While I do have a handful of new systems - or fairly new at least - I use old systems from the 80s and 90s every day. And while these...

Last week we found that some of the contacts in the card reader were intermittent, so we could not reliably run diagnostics. We borrowed the card...

Not my stuff, but it's my opinion- as someone else who has given away stuff, but also won't ship (not worth the hassle and shipping is crazy these...

Its possible, check for damaged components on the neck board. If the supply output voltage had dropped due to current overload, one would expect...

Thanks Dave, I finally got a clean uncluttered work bench again so have setup my signal generator and oscilloscope to try your suggestion. I made...

PM me and I can send you an image you can dd onto your own SD card... Setting up is difficult unless you have all the disks and or emulation on an...

The Calcomp 140 drives use a "positive pressure air system" according to the "Calcomp 140 OEM Manual" (page 14). This makes sense and I have now...

was a great get together, l enjoyed catching up with the usual suspects and happy to meet new faces, looking forward to the next one!

There's a datasheet for the VDP ( HD63484CP98 ): https://pdf1.alldatasheet.com/datasheet-pdf/view/144401/HITACHI/HD63484CP98.html Looks like it...

Has your install of System 7.1 previously experienced any crashes from misbehaving applications like MacDraw? It only takes one system crash to cause...

I have been struggling with the airflow in the RX01 floppy subsystem which uses Calcomp 140 drives, but had a break-through when I read the manual. ...

Why opt for such a 'small' microcontroller when nice alternatives like the Teensy 4.0 are available? Lots of Flash and RAM and a tiny footprint. I...

So I tried a little tsr which installs itself into 0x1C interrupt, but that interrupt is used for games and programs so it crashes (in dosbox). ...

In case of "won't ship" - and if something interest me - would You(and others reading this forum and probably in future) allow to sending someone to...

Progress on the computer: the HardCard 20 has been successfully repaired and it boots up. The keyboard's foam contact pads are disintegrated and...

Unfortunately I don't have a supply capable of 125V. I have a variac, and could use that with diodes and a cap, but there would be some ripple and...

Yes, address $0000 looks fine. However, the interesting thing would be address $0001 (as stated back in post #164). The fact that the machine...

Yes, I agree it should be zero, unless say it was being cyclically triggered and the SCR coming in and out of conduction, and what we are seeing is...

As you say, I guess the problem is the planar nature of mode-x, that asks to change the memory bank (plane) in order to see all the pixels. The dump...

Thanks Jan for sharing the photos, I will add the MS-DOS one here. I wonder what the story is behind this port? the screen shows: MS-DOS Loader...

I have researched this subject extensively before building my ultra-quiet MicroVAX II. Bottom line is, DEC designed the BA23 to be cooled to spec...

Thank you, but these are describing the EMUF, the older Z80 variant. The mini-EMUF uses the Z280.

If you think it could provide clues, I could disconnect +125V from the monitor, and connect that to a programmable load, and find the point that it...