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That's a good point, these chips are pushing their DIP40 packages. I'm not an EE, so I couldn't tell you if the Sequencer chip needs two grounds, but if we wanted to read the map mask register, we'd have to sacrifice one.

Most of the EGA registers live on one of the 5 custom LSI chips (save the External registers which are named quite literally, and are indeed some type of 74). IBM designed these chips themselves (unless they contracted it out...), so my conclusion is that they just hated us. Only the CRTC chip...

Powered it on, seems to spin up. No flames shot out of either end (of the computer or myself) , but it does not boot. I sadly don't have a 5.25" dos diskette or anything I want to reformat so it may have to wait until I can get a gotek in and peek around in fdisk. I made sure the jumpers were...

Sorry for the somewhat-necropost, but I'm working on Tandy 1000 emulation in MartyPC and would love to test to see if this program works. Do you have an updated version you could share?

I picked up the 10MB version, the 25-1025 this weekend at VCF, with controller card. I haven't tried to fire it up yet.

You can't just run the CPU in the PC in minimum mode, all the bus signals are hooked up to the 8288, which can't understand the CPU in minimum mode. DMA, strangely enough, isn't a problem. The DMA controller doesn't do bus mastering, the motherboard DMA logic just pulls the ready line low and...

If you want animation you might look into the FLC format (FLC/FLI/FLA) I recall these being more popular than animated gifs back in the day.

Ah cool; VT-52 it is then. Thanks for taking the time to answer my questions.

what kind of terminal did it expect? Just curious if i should pull in a proper terminal emulation library or if i can hack up a simple serial "video card"

I don't know how happy it was, but it ran. This was at very low frequency. I can attempt with an AMD D8088 and see if it behaves the same. I just happened to be well-equipped to perform this test as I have an 8088 Arduino MEGA hat which I had modified for an Arduino GIGA by snipping off the 5v...

I think this is the right track. The request/grant mechanism follows roughly the same rules as prefetch aborts: For a request to be honored, all of these conditions must be true: Request occurs on or before T2. Current cycle is not the low bit of a word. Current cycle is not the first...

I'm not attempting to run two 80c88's in parallel. We were just discussing whether VCC was enough to 'disable' one of the CPUs, and it least for the CMOS version it is not.

I just did a test with a Harris 80c88. It will happily run with VCC pin completely disconnected

I am interested in emulating the earliest versions of 86-DOS. As I understand it, this would entail emulating the following: an S-100 system with an 8086 board (will be 8088 initially, until I can write a new BIU for the 8086) a 8086 support card which has two PICs, some timers, serial and...

Er, why would you need to?

And vcc is not an on/off power switch. depending on the IC interesting things can occur even with it disconnected...

Very cool! Your emulator has some really cool features. File drag n' drop into FAT filesystems? Wild. Just an aside - not that I care too much about attribution, but - although the 8088 tests live in Tom Harte's repository, they were primarily generated by myself and a friend helping out using...

Glad you found them useful! Curious what bug you found :) Do you have a link to your emulator?

You'd think 16.7 ms would be a short enough period of time, but when I was implementing keyboard support in my emulator I was sending a scancode per frame to the core and quickly noticed a fast typist can generate multiple scancodes per frame, especially when you consider keyup/keydown.