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DOS TUI library (C, OpenWatcom-compatible)

Posted on 2021-12-22, 23:16

Hi folks, I'm trying to write a very simple setup application for some hardware I'm working on. It's based on mTCP, so it's a cross-compiled C program and I'm building it with OpenWatcom. I'd love to integrate a very simple TUI like in many of the commercial setup programs (like RSET8019, Sound …

Re: With all of great new ISA sound cards coming out (even with FPGA), what is theoratically stopping a PCIE implementat

Posted on 2020-12-03, 20:49

And if you need lower latency, just up the USB polling rate. Hi, I built that project. As far as I'm aware (and I'm not a USB expert by any means), USB FS has a fixed frame timing at ~1ms per frame. USB HS can do 125µs per frame. Even with 125µs, that's only 4000 bytes/s, aka 4KiB/s. And that's in …

Re: Using an ISA VGA card on an AVR

Posted on 2020-10-15, 20:52

It's very much related and I think we're both at the same point now. USB CDC-ACM is basically just serial over USB, very simple protocol, basically just writing plain text data into endpoints and it's done. The latency isn't great, but I haven't done any measurements yet. Gut feeling: ~1ms per ( …

Re: Using an ISA VGA card on an AVR

Posted on 2020-10-14, 21:42

[..] what is your purpose of doing this? I wanted to learn about PC busses (ISA, PCI, etc.) for a while now. I'm also building a RC2014-based Z80 computer, which would benefit from a nice VGA output. All currently available options are either too modern (ESP32, Pi Zero, etc.) or too crappy (40char …

Re: Using an ISA VGA card on an AVR

Posted on 2020-10-14, 20:17

Hey, I've made quite a bit of progress on this topic: IMG_9670.JPG IMG_9671.JPG IMG_9653.JPG I've overcome my hesitation to deal with USB in order to get this to work properly :) This PCB ISA card is using an STM32H743 microcontroller to talk to the ISA bus. I'm using an already open-source and …

Re: Using an ISA VGA card on an AVR

Posted on 2020-09-13, 16:47

Have you ruled out timing issues? Not really. I have a lot of delays in the code and the AVR is pretty slow in general. The AEN and ALE lines could be part of the problem. I'm currently not using both of these, AEN is pulled low permanently, ALE is pulled high. Additionally, the card might try to …

Re: Using an ISA VGA card on an AVR

Posted on 2020-09-13, 14:35

BloodyCactus wrote on 2020-09-13, 14:26: I also assume you meant 0xB8000 I've tested the whole range between 0xA0000 and 0xBFFFF to make sure nothing works. The RAM chips now get pretty hot (~40-45°C) after the init works, so I'm guessing that the refresh works as intended.

Re: Using an ISA VGA card on an AVR

Posted on 2020-09-13, 14:06

Any idea what's preventing you from writing to the video RAM? Not quite, yet. I/O Read/Writes work fine, I know that because I can do all the Plug & Play stuff. Also, most of the VGA init (CRTC) works fine. Memory reads also work fine, because I can read the video BIOS (at 0xC0000), which is using …

Re: Using an ISA VGA card on an AVR

Posted on 2020-09-13, 01:25

Good news: VGA init seems to work now. I've integrated support for this device into PCem (more specific, the tvga.c driver) and it's now directly controlling the real card. This allows me to successfully initialize the card (and the VM can boot into DOS). Unfortunately, writing into the video RAM …

Re: ATA/ATAPI IRQ line vs device select line?

Posted on 2020-09-11, 19:04

What happens when a device would be requesting an IRQ(e.g. slave) and it's not selected? Nothing, the device will not drive the INTRQ line. The host will either track which devices it is expecting interrupts for ( linux does this ) or it needs to check/poll the status of each device. To quote from …

Re: Using an ISA VGA card on an AVR

Posted on 2020-09-07, 12:23

I don't think this will be particularly high-performance in the end, mostly because I'm not going to use ultra high-speed hardware here. An FPGA using PCIe on one side and ISA on the other would be ideal for this task, but that's way above my target here. I'm mostly hoping to get some (slow!) VGA …

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