8088 PC XT Compatible On An ISA Card. Second Build.
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- Опубліковано 19 жов 2024
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Thisis such a cool project! I can't wait to see how it develops.
Cool board. I’d love to get one, I’ve got an Amiga 2000 with an ISA backplane built into it, I’d run it in there.
Nice design. A bit more minimalistic than mine Xi 8088 :) Regarding floppy support, BIOS, etc., try using my 8088 BIOS instead. It's got the support for floppy drives larger than 360 KB and other useful features.
I will have to try it. Have you gotten up to a 1.44mb drive to work?
@@elijahmmiller yes, and also 2.88 MB, although that requires an FDC that can do 1 Mbps
Nice. How many layers do you use? Was that thing hard to route? I'm trying to route a fpga video card with a 16 bit data bus and 20 bit address bus and boy is it a nightmare.
This is a 4 layer board. For the routing what I do is on one side the traces only go right to left and the other up and down. And the middle layers are the same. This keeps them from tangling up.
Consider a daughter board for math coprocessor in future build.
The system runs in minimum mode. I have been looking at adding an 82188 bus controller because it can handle both the 8087 and 8237 requests. I think in total it would add 3 chips to the system.
Have you considered using a GAL like the 22V10 or 16V8 for the line selection? Would be a lot smaller than an EEPROM.
I have. One day I may try it out.
Can the V20 be clocked at the full 16 MHz spec in this board? After playing with these old systems I find that 8 MHz is just a bit too slow for anything interesting I want to do, but around 16 MHz is where the sierra SCI game engines start to run at full speed.
I have found anything over 10 mhz doesn't work well with the ISA bus. It is just too fast. I think you need to have an external bus controller that keeps the speed of the ISA bus below 8 mhz. Or something that inserts some wait states into the bus cycles. I have had some luck with a prototype running at 16 mhz.
Did you already sell out of the PCBs?
No I have one blank left. I am out of town this week so I paused the eBay listing. I have 4 on my desk mostly built that I am waiting on some ROM chips to finish them out.
What Serial Card model of Mouse do you use?
Thanks for sharing.
It is a generic multi I/O board. I think the brand is Gold Star.
So, it's a SRAM based memory running on, as you don't have to provide DMA0 refresh cycles?
Correct it is all SRAM. One advantage of the lack of the DRAM refresh cycle is there is a noticeable overall speed increase.
Of course!
SRAM is what's used for cache even today, on cpu dies.
I know YOU know this, but others might not.
Can you make simple Hercules two layers single chip card to reproduce?
I haven't ever looked into making a Graphics Card. Do you know where some good schematics are?
@@elijahmmiller GitHub, but most CGA VGA cards replicas are complicated. I remember the most simple cards were single W86855AF chip based HGC I thought you might have such a card.
Will this plug into an ISA bus in a Pentium class machine and boot?
No it would interfere with the Pentiums Address and Data bus