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Thread: Tandy 1000 Adapters - expressions of interest?

  1. #11

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    Quote Originally Posted by Tibs View Post
    Then probably just need one with two slots.
    In that case (assuming it works) my intention is that you would buy 2 adapters and put 1 in each socket - it's just easier for me to make a single design that works for everyone with the ram expansion.

    PS the NEC V20 upgrade is apparently worthwhile for EX/HX owners as it add's support for some useful 286 instructions making the compatible software pool larger.

    Last edited by dJOS; July 21st, 2017 at 06:01 PM.
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

  2. #12

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    Quote Originally Posted by keenerb View Post
    Something like James Pearce' 1mb memory card would probably work in the riser. Doesn't offer DMA capabilities but if all you're looking for is memory expansion past 128k it'd be sufficient.

    An EX/HX with 1MB expansion + non-DMA xt-ide would actually be pretty usable.
    I guess the XT-IDE would would in PIO mode but it'd be extremely slow as the CPU has to do all the work for everything, the BIU mode (using the 8088's Bus Interface Unit) might also work too.
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

  3. #13
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    Quote Originally Posted by dJOS View Post
    My understanding is the PLUS-Ram card has a custom DMA controller integrated into the memory controller chip - without it only simple cards like a serial card / modem will work. Anything else like an ethernet card or IDE controller wont function without it.

    Without the PLUS-Ram card there is no DMA function in the system - once installed it makes a noticeable difference to the speed of the machine, even the floppy drive speeds improve.
    That's completely not true. PIO IDE works just fine (what XT-IDE uses). The only thing it accelerates on the stock system is floppy drive access. Nothing else get's sped-up. Even most network cards work just fine without DMA. Many early Ethernet adapters do not even support DMA (eg. NE1K/2K, Xircom, etc) and many more do not require it.

    I had layed out a memory mapped Plus card similar to JR-IDE with the addition of two serial ports, but never could find a solution for the elevated 62 pin connector. The best path I found forward was, possibly, to make a two card set with a normal-ish height female connector downward and slightly taller male connector upward. One card with RAM, IDE, serial. Maybe the other with.. ?
    "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

  4. #14

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    Quote Originally Posted by eeguru View Post
    That's completely not true. PIO IDE works just fine (what XT-IDE uses). The only thing it accelerates on the stock system is floppy drive access. Nothing else get's sped-up. Even most network cards work just fine without DMA. Many early Ethernet adapters do not even support DMA (eg. NE1K/2K, Xircom, etc) and many more do not require it.

    I had layed out a memory mapped Plus card similar to JR-IDE with the addition of two serial ports, but never could find a solution for the elevated 62 pin connector. The best path I found forward was, possibly, to make a two card set with a normal-ish height female connector downward and slightly taller male connector upward. One card with RAM, IDE, serial. Maybe the other with.. ?
    yeah you are correct, I did a bit more reading on PIO etc after posting that.

    the smart option for your idea imo would be to use a single 8-bit ISA slot on the PCB and have an optional riser-card to add a pair of ISA Slots in the horizontal plane.
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

  5. #15

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    Quote Originally Posted by eeguru View Post
    That's completely not true. PIO IDE works just fine (what XT-IDE uses). The only thing it accelerates on the stock system is floppy drive access.
    So just been doing some reading which seems to suggest that without the DMA controller you dont get the 16 color TGA graphics modes. If that is the case then it'd make Tandy gaming a bit pointless on an EX/HX.

    EDIT: but then the original 1000 didnt have a DMA controller at all... Hmmm.
    Last edited by dJOS; July 21st, 2017 at 11:28 PM.
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

  6. #16
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    The ISA adapter is of interest to me. Either an 8 bit SCSI card for an external drive or an 8 bit IDE card with a flash drive would be cool to have (assuming they fit).
    What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
    Nubus/ISA/VLB/MCA/EISA cards of all types
    Boxed apps and games for the above systems
    Analog video capture cards/software and complete systems

  7. #17
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    Quote Originally Posted by dJOS View Post
    So just been doing some reading which seems to suggest that without the DMA controller you dont get the 16 color TGA graphics modes. If that is the case then it'd make Tandy gaming a bit pointless on an EX/HX.

    EDIT: but then the original 1000 didnt have a DMA controller at all... Hmmm.
    I think the RAM upgrade card for the original 1000 added DMA (have to dig mine out someday).
    What I collect: 68K/Early PPC Mac, DOS/Win 3.1 era machines, Amiga/ST, C64/128
    Nubus/ISA/VLB/MCA/EISA cards of all types
    Boxed apps and games for the above systems
    Analog video capture cards/software and complete systems

  8. #18

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    Quote Originally Posted by Unknown_K View Post
    The ISA adapter is of interest to me. Either an 8 bit SCSI card for an external drive or an 8 bit IDE card with a flash drive would be cool to have (assuming they fit).
    Cheers.

    I managed to buy way more ISA slots (50) than I'll likely ever need, the only thing I will need is more right angle headers and maybe another run of PCB's.

    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

  9. #19
    Join Date
    Aug 2013
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    Philadelphia,PA area
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    Quote Originally Posted by Unknown_K View Post
    I think the RAM upgrade card for the original 1000 added DMA (have to dig mine out someday).
    The DMA controller on the RAM card is a standard 8237 DMA controller chip. Not sure why the HX/EX would need a custom DMA controller.

    Tom

  10. #20

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    Quote Originally Posted by hornbetw View Post
    The DMA controller on the RAM card is a standard 8237 DMA controller chip. Not sure why the HX/EX would need a custom DMA controller.

    Tom
    Space reasons, it's an Intel 8237 plus memory controller in a single chip.
    My Retro Collection:
    CBM: C64, Amiga 500 x2, 600 & 1200
    Mac's: SE, LC630 & Beige G3
    PC's: K6-III+ 500 System + Roland MT-32 & Tandy 1000 EX 640kb, 3.5" FDD, CF-IDE 4GB HDD
    Visit my Tindie store for Tandy 1000 Adapters for EX, HX, SX, SL, TX & TL etc

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