Recent content by CommodoreZ

Finally caught up with my video backlog, this is good stuff. Thank you for preserving the history of this machine. I was expecting a TVT 6-5/8 or something, rather than an S-100 board, that's cool. A few years ago I asked a few Apple I fans if anyone had kitted out a modern replica with a...

74151's and 74138's with a little extra logic to compensate for being separate chips should do the trick.

This right here is the kind of thing I'm going for, thank you. I was also supplied with this schematic elsewhere from Polymorphic Systems for the Poly-88 and 8813. No specialty IC's, no dedicated keyboard encoders, not even ROMs -- just pure jellybean logic. I think this might be my baseline...

The link to the previous iteration of this forum doesn't appear to have been archived, so those breadcrumbs are long gone. It's also worth noting that the OP of this thread passed away in 2018.

When it came to homebrew computer projects of the 70s and sometimes 80s, the ASCII keyboard is talked about alot, but now kinda relegated to the unobtanium due to keybhoarders and keycap/switch harvesters. So obviously people have come up with new designs to fill the void, which is great. I've...

Try this link: https://www.ebay.com/itm/396825731326

How bad is it, beyond the structural/cosmetic damage we can see?

So, on the 8K core plane I've been using, I ran the 1200 Logic Test for like 80 minutes non-stop, and it ran without issue for the duration of the test. Then I switched over to the Memory Checkerboard III test, which also ran without issue for over an hour, no faults detected or reported. I...

I fixed it? I honestly don't know what happened. I replaced U42. And the tests kept failing. So I had my hand-entered diagnostic routines tested with a second set of eyes. Turns out I had some bits wrong... human error. :oops: I still don't know what initially caused the fault that sent...

Windows 95 OSR2 sounds like a great choice. As for software, 95 Plus!, Photoshop 4, MS Office 97, Command & Conquer, Red Alert, the Microsoft Best of Entertainment Pack, LEGO Island, Atomic Bomberman, Lode Runner Online: Mad Monk's Revenge, Rollercoaster Tycoon, Warcraft I and II, MS Flight...

Okay, we may have found the point of failure, and it's upstream of the part being explored per post #101. This N8271 shift register is used to store a bunch of states as we progress through processing. The signal we care about is how IO*E is generated from IO(F+D). Presumably, that data is...

Right, so look at the examples above: most of them don't bother to do that. The OSI-300 doesn't even care, it wants you to start from scratch each time with a reset CPU, and it accomplishes its goal. In order to single step an NMOS 6502, you keep the clock running, and instead control single...

I think that one is a modern machine. Awesome work, but again this modern machine made in the past few years. The thing that killed the front panel was the birth of the Appliance Computer, caused by a combination of circumstances of which came to a head in 1977. I've explored this aspect in...

From novasareforever.org: 096-000150-01__Nova_1200_Logic_Test_095-000036-01__1970-1974.pdf which is the manual for 095-000036-01__Nova_1200_Logic_Test__1970-1974.ab

It wasn't U11. As far as I can tell, the "P" pulse refers to a special pulse used for interacting with I/O devices. When a No I/O Transfer instruction is sent, which device it applies to depends on the last 6 bits of the instruction. Device code 0 refers to the CPU, and is sort of a dummy...