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  1. Nicolas Welte's RAM/ROM board ROM structure...

    Quote Originally Posted by misterdid View Post
    I found it...the flash is banked by 32k chunks, with a 1:1 mapping from $8000-$FFFF (FLASH $0000 = PET $8000)
    Good find. That makes sense, map the base of rom to $8000 to make decoding simpler, and then exclude video ram and IO space using the GAL chip.
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  2. Idea for new SoundCard for PCMCIA Type II equipped laptops......

    Been hanging around Vogons watching the "New PCMCIA Card" thread....which turned out to be a misnomer....so I guess "Party On" for me.

    Considering the number of reproduction soundboards being put out as of late - you have Sergey's Adlib, you have a Gravis UltraSound clone, you have someone working on an AWE64 clone.....I'm surprised nobody has attempted to make a PCMCIA card, especially since that's something people in the retro-gaming community tend to pine for ...
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  3. PS/2 Model 25-286 ISA Riser

    Quote Originally Posted by TheDrip View Post
    This started off as a project to reproduce a riser for the Model 25-286 board. The only one I could get my hands on was $40, for a little 2" by 7" PCB, no components at all.

    After some thinking, and some inadvertent prodding by bladamson who is making his own riser, I decided I could add some amount of functionality with the spare board space.

    This is what spawned my tinkering the other night, adapting a Malinov FDC controller PCB into a UMB provider, here.
    ...
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  4. When the mood to tinker strikes ...

    Quote Originally Posted by TheDrip View Post
    I have been putting together a replacement ISA riser for my Model 25-286 and decided I had enough room to fit a small SRAM to provide UMBs.

    In theory it will work so I sent the gerbers out for fab. I got in a mood yesterday and decided to mock up the UMB circuit. A floppy controller card from Sergey was sitting nearby and has most of the signals in mostly the right places.

    What you see is 128K of memory, mapped by a GAL in 4K blocks. C800-DF00 for my Model 25 (with
    ...
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  5. Any interest in a PCjr CPU upgrade board?

    Quote Originally Posted by Eudimorphodon View Post
    Maybe the photo isn't clear enough to be sure, but it looks like that's made out of machine pins. Plugging something like that into the standard cheap wiper sockets tends to kind of mess them up if you ever want to put the original CPU back in.
    Are you saying to insert a spare socket into the socket? And then put the board into that socket?
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