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Thread: Tandy 2000 - Envision Designs upgrades

  1. #1
    Join Date
    Nov 2012
    Location
    Richmond Hill, Ontario, Canada
    Posts
    1,145

    Default Tandy 2000 - Envision Designs upgrades

    I just acquired a Tandy 2000 and was a little surprised when I saw it come up with 896K in the eBay ad but didn't see any extra memory interface cards. I popped out the motherboard and found the Envision Designs 896k memory upgrade and the 8087 Math coprocessor upgrade. I figured someone here would find this interesting as I have read they are uncommon upgrades. Now I need time to researching how to make some boot disks.

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    Santo
    Last edited by snuci; September 23rd, 2019 at 06:14 PM.

  2. #2
    Join Date
    Mar 2011
    Location
    Atlanta, GA, USA
    Posts
    1,499

    Default

    I did a 800K memory upgrade board for the 2K but it's a replacement for the standard 256K upgrade board that takes up a slot. I'm happy to share that work if anyone is interested. However I was going to wait until I had time to get back to 2K projects and add an IDE type interface to it with a BIOS & DOS upgrade to support it.

    I disassembled and reverse annotated the planer BIOS and some of the supplemental BIOS code that is loaded as part of IO.SYS. The former is on Malcom's github. I believe it's possible to make a BIOS replacement that would allow non-Tandy OEM DOS versions to load - maybe even 6.22 or FreeDOS. It would still be a 'work-a-like' in that anything that went directly to hardware would break. But anything that is BIOS/DOS access only would work. I think it's even possible to redirect some soft-interrupt calls so keyboard ISR chaining might also work.
    "Good engineers keep thick authoritative books on their shelf. Not for their own reference, but to throw at people who ask stupid questions; hoping a small fragment of knowledge will osmotically transfer with each cranial impact." - Me

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