In no particular order.
Just drawn another #ISA board. Just to come out clean, this is not (fully) a project of mine: I just took the lo-tech EMS board (https://www.lo-tech.co.uk/wiki/Lo-tech_2MB_EMS_Board), added more RAM (4 Meg total), made it through-hole, added an optional ROM socket and a LED to indicate when the RAM is active.
I plan to use this to have hardware EMS+XMS in my 286. As usual, will release everything once I build it and verify that it is mostly working! #retrocomputing #homebrewcomputing
Found out that the Winbond chipset on this 286 mobo has embedded EMS mode for RAM above 640k (if you load an ad hoc sys module and configure the option in the BIOS). The sad part is that I found no way in hell to gain upper memory, with the exception of wasting ALL the EMS memory for it. Gah! #retrocomputing #wolfenstein3d
Ew, pretty busy #weekend, but had some time for yet another iteration of my serial/parallel ISA card.
I replaced the two 16C550 with a single 16C554 (for a total of 4 serial ports!) and added circuitry for an expansion ROM (going to save me an ISA slot on a few 286/386 machines).
I think I'm almost at the end of the testing for my dual UART + Parallel port #ISA card: reorganized the pinout for the parport header and updated the IRQ logic to match the schematics of the IBM AT. Now every diagnostic I throw at it passes without issues. Time to prepare to print a rev 1.1 and then release? #homebrewcomputing #retrocomputing
Interesting that my autocorrector replaced "need" with "nerd". Still, not so wrong...
Built two #ISA #8bit #backplane boards by Sergey. One I will keep as a spare to test cards, the other is going to be part of a longer term project (want to do another XT build: plain 8088 this time, no V20, game blaster clone audio.. Maybe an EGA card if I can find it)
Autorouting an #ISA card that features a parallel port (taken from the original #IBM PC Technical Manual) and two serial ports. In a few weeks I'll see how many mistakes I made. Now I'll go relax a bit with a #book. My brother gifted me the first one of #thewitcher series, can't wait to start it. #homebrewcomputing
In no particular order.
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