tomicdesu

I built this MP/M computer using Teensy 4.1, which uses a modern PC type keyboard via "USBHost_t36.h" and attached to Teensy. Works great. I tested it through a hub and that works too. But I've got one person trying to attach their keyboard...

@tomicdesu - Just received the enclosure 😁 It looks really nice. I hope to get some time soon to assemble it. Thanks again...

No, it's clear as mud. A couple people have asked for this. I'm missing a "spec sheet"! I will do this...

OK! Friendly fZ80 Computers are now for sale on eBay: https://www.ebay.com/itm/205876956191

OK they're "done" haha. Complete enough to be shippable, they seem solidly reliable and I've got 10 I will post on eBay on Wednesday 26 Nov 2025. If someone here wants one let me know ASAP, before they go on eBay. Or if you prefer, contact me...

Yeah, sorry to undo all your work!! Except for the three-arg write, nothing I've changed is incompatible. I just needed to get out from under this bug. It's now quite repeatable so I can revisit it later when. fZ80 doesn't use as much stack as...

Man, you just can't seem to get a break o_O I am setting up the Arduino fZ80.6 for compiling right now. I looked at your stripped down version if VGA_4bit_T4. Whatever it takes to stabilize the code;)

OK! I uploaded the correct released files and fixed some broken links. The upgrade process, for all the changes, is just re-flash, copy the contents of one of the bundles onto your A: drive, SYSBOOT the new CBIOS.HEX, and press reset. Fixed up...

Aargh the release has a bad MP/M XIOS in it, interrupts off (a test copy). Will fix today. Sorry for that. Will let you know.

I wrote this up for myself, to go into the source. But it tells the tale above. linearly. At the moment I'm using a very stripped out version of VGA4BIT, which I'd done initially looking for bugs that might write into my Z80 banks in the same...

Yeah it's very weird. Now CP/M doesn't do this! And the Teensy code is the same! CP/M also has a (very simple) timer tick. ANd it can run multi-window, or not, so that code isn't it. This is why I was so baffled! I couldn't see how it wasn't MP/M...

Didn't fix it.

OK will do! Oh, I don't actually *understand* the VGA/DMA code! lol. Honestly I haven't tried; I worked around it; I have a ton of krap to do to get out from under this grown-insanely project! But I will not forget it. I've snapshotted a...

I was going to say that bug sounds like a cache issue... then realized the original VGA class code didn't actually have any cache handling included in it.... It's probably better to use arm_dcache_flush() rather than arm_dcache_flush_delete()...

Thanks for the tip @jmarsh. So instead of: arm_dcache_flush_delete(s_frameBuffer[frameBufferIndex], fb_height*_pitch); Change it to: arm_dcache_flush(s_frameBuffer[frameBufferIndex], fb_height*_pitch); Will try it out and see if there are...

How about Vivid Red:D

Sure you want flat black? I use Montana paints, the graffiti folk use them. Amazing colors. Here's the choice, lol. https://www.montanacolors.com/en/productos/mtn-94-aerosol-spray-paint/ I've been thinking something bright, and...

I've been working almost (no, not almost, ...) obsessively getting the fZ80 reliable. I had a huge random-memory-corrupt error, a true heisenbug, that I finally traced solidly to interaction between the IntervalTimer object and something in the...

Nice:)I had forgot about that discussion...

Wow! OK that's a lot. I think there's something really interesting here. Is there some sort of p-code machine you could write/find an efficient interpreter for? And make a dense, succinct general purpose machine from? With high level...

Cool. I'm finishing up the current revision. It's quite a lot of work done. Reliability all around is up, as is performance. MP/M II 2.1 is half way to usable in a modern sense. I'm editing in one window, compile and test in another, and can be...

Thanks, It works perfect (y) I really like that you keep margins on all four sides when resizing the panels. That way all four panels are always in view. I am working on a complete rewrite of a file manager for the Teensy that I had cobbled...

Touche! My slower response! lol I had not been keeping track of card format, FAT16, FAT32, etc. Regarding the SD card read error, SD_CARD_ERROR_CMD18, frequently reported when accessing either of the removable SD cards... I had them wired in...

F1 through F12 are the window-changing keys. I think F12 brings up the big cross cursor. You've run VGA M to get into multiwindow mode? You see four windows? F1..F4 selects window 1..4. In the version you have, F12 should bring up the resize...

You could always tie this code to an i/o pin. void doReboot() { SCB_AIRCR = 0x05FA0004; }

The main 2 reasons are size and history. Since Teensy 1.0 in 2008 only a single pushbutton has been used, dedicated to the purpose of entering programming mode no matter what has gone wrong in the software. The most popular non-Teensy boards on...

I think the current Teensy design is great. The funny port write resolves my weird corner cases. One of the major complaints from computer folk at the time (I was probably one of them; I just don't remember) about the IBM PC's and workalikes was...

I've got a project that is externally USB powered AND has the USB cable from the Teensy to the development machine. I have to unplug two cables to power it off. During debugging it's a PITA to do that. I've built a computer with emulated CPU...