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To test a bare Tandy 1000 HX motherboard before hacking together a keyboard I made a boot disk with an ancient version of PC Anywhere on it set up to run through my homemade serial card, and for...

Slightly related funny story: back in the day ("day" being 2004/2005 timeframe) I noticed the "platform" guy at work was using some PATA disk drives with SATA adapters on a machine in his...

Frankly with that vintage of software once you have a device that can do, I dunno, a couple megabytes per second in sustained read speeds, which almost all flash devices (All but the most ancient and...

I did specifically say with reads. Yes, "simple" flash devices suck with writes. Granted I've hardly ever cared about write performance because, well, gotta be honest, with most of what I do with my...

FWIW, there are CF cards that do support TRIM, but you also need OS support for it to make a difference, and I can't off the top of my head think of a lot of OSes that support TRIM that'd run (well)...

Cheap multimeters with analog meters are junk (as are older analog ones that haven't been well preserved), but I've had mostly positive experiences with dirt-cheap digital units. Have one I bought at...

The Model III's basic scan frequencies are roughly NTSC compatible, but the machine uses a really slow dot clock for its 64 column (512 dot wide) display. It's only about 10mhz, and if you do the...

My point was that unless you pay someone to put it together for you a raspberry Pi or anything else (and I guess I got confused by the repeated invocation of Intel-based Pi-like-things as if they...

Have to admit I'm left scratching my head exactly how buying a single-board computer automatically helps with this situation. (Granted we have no idea what this situation even *is*.) If the person is...

Looking back it feels like Christmas 2018 was their last Hail Mary attempt to pull back from the Event Horizon of the black hole that had been inexorably tugging on them for years. They were decently...

This question requires a lot more information to answer meaningfully. (The big one being the exact vintage and platform.) I've successfully played with LPT redirectors on my lowly Tandy 1000 to print...

You'll probably need to bake your own BIOS if you leave out DMA.

Bad suggestion: I think there's a disassembly of the original Tandy 1000 BIOS out there, those machines have a conditional in their...

This is off the top of my head, but I'm reasonably certain that with the 808x all addresses are byte-sized, which means that:

* 16-bit transactions can only happen against "even" addresses, and...

The Compaq's monitor is indeed not composite, it has an analog video line for the grayscale and separate sync lines. But for the record, the reason the 5155 has that "trashed text" issue isn't really...

Shadow mask pitch is also a significant factor when you get down to sub-13" color CRTs. Most tubes that small just can't physically quite do 640 vertical lines with complete clarity. If the monitor's...

Between the info on that page about making custom fonts for the terminal and pictures of the display showing pretty wide "scanlines" I think its vertical resolution is closer to 300 lines, but I have...

Does anyone know the specs of the video output of the VT320? Several sources repeat that its resolution is "800x500", but that doesn't vibe with the information here saying the character glyphs were...

I second this theory. The '374 is the "clocked" version of that type of latch, I suspect it's set up so it latches when it receives a "strobe" signal from the keyboard.

Thanks! I’m actually kind of amazed how ‘easy’ it was to get honest-to-goodness PHI clock sync working for video, and I’m kind of proud of the brainwave I came up with to enable using unified memory...

... it's sad, I'm actually considering the idea of using a 15ns 32kx8 SRAM as a keyboard converter for the Commodore hackclone project because even though it would only be using 10 bytes of it the...

I have vague memories of reading once that it was standard with TRS-80 key scans to read the "255" row (which is activating all the row lines at once) to see if "any key" is pressed down and then...

I was mulling over the idea of using dual-port memory for a TRS-80 keyboard matrix converter instead of one of those analog matrix switches, but it seems like a potential drawback is if you want to...

Update on the PET(-like) video card project: It's officially a computer now. As of Friday I can run an ancient version of the PETTESTER ROM I wrote back in 2011 on the breadboard after interfacing a...

I think people get confused comparing the 6845 to more “complete” graphics chips like, I dunno, a Commodore VIC. *All the 6845 does with RAM* is increment a set of address lines according to a...

Graftabl only works on CGA in graphics mode, IE, when using software mode to draw “pictures” of letters. CGA likewise doesn’t actually support redefinable “text mode” characters. A completely...