Thank you so much for this.

I have a very basic (but working) DMA implementation for this project, which has no wait state in the CPU regarding access to the memory bus, and magically performs any pending DMA Transfers in a dedicated thread. Plus, the DMA controller emulation is bare bone. It's only there so Sound Blaster PCM transfers can work (and they do).

Overall in the future, especially for floppy drives, this is not gonna cut it, and this will really help in the far future (once Dune is entirely rewritten) to guide a new implementation. 😀

Ooo, Spice86 looks like a really interesting project! I've been pondering writing something like that myself for a while. I'll have to try it out.

My next post covers CGA wait states, basically just a follow-up to and expounding on one of reenigne's blogs.

reenigne's original post: https://www.reenigne.org/blog/the-cga-wait-states/

https://martypc.blogspot.com/2023/05/explorin … ait-states.html

Great work!
These blogs explain exactly what I've always been so critical about regarding PC emulators:
Firstly, cycle-exactness matters.
Secondly, cycle-exactness does not stop with the CPU alone. The CPU does not operate in a vacuum. It interacts with other devices on the bus, so any externally observable effects on the bus (mainly wait states) need to be emulated in a cycle-exact manner.

just another note of appreciation, and great that its on a regular website that will be searched by google and other search engines, enabling folk to find it readily

New post is up, on the topic of emulator hardware validation.

https://martypc.blogspot.com/2023/06/hardware … g-emulator.html

Saw the thread about running Area5150, awesome work, congrats!

And the built in debugger is what I was looking for a long time, excellent!

Could you please add Adlib / Soundblaster device?
How accurate is the VGA emulation?
Will it build under linux?

Just perused your DMA article. Scrolled through it a bit, haven't deeply dived into it yet. But all in all it looks well-writted and detailed, with good illustrations, and using understandable language.

Thanks for doing such extensive research, and sharing the fruits of it with the world. This is historically relevant. 🙂

TheMechanist wrote on 2023-06-10, 19:21:

Could you please add Adlib / Soundblaster device?

Eventually...

TheMechanist wrote on 2023-06-10, 19:21:

How accurate is the VGA emulation?

Not very; it is a "draw the VRAM every frame" sort of implementation, for speed, and there are many missing parts like CGA emulation, unchained modes, user-definable fonts, etc.
All the registers are present though, and there's a nice debug display for them all, including a live view of the palette color registers, which is neat to look at. My release builds will continue to be CGA only until I am happier with the EGA/VGA support.

TheMechanist wrote on 2023-06-10, 19:21:

Will it build under linux?

Yes, I use Ubuntu for profiling.

Finally squashing a longstanding bug.
https://martypc.blogspot.com/2023/06/emulator … uring-boot.html

More debugging adventures with PIANOMAN
https://martypc.blogspot.com/2023/07/emulator … ianoman-30.html