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FS: Tandy 1000HX / 1000EX Memory PLUS Expansion card, fully populated
- Thread starter mrarkus
- Start date
eeguru
Veteran Member
Wow nearly $100 with 5 days to go... really highlights the demand for these. I just wish the high-extension 62-pin .1" shrouded headers were not so unobtanium.
Has anyone ever tried 3D printing a shroud for male pin headers? I suppose printing it such the holes are a fraction smaller than the pins, heating the pins with a hot air gun, then pressing it down might work... /shrug
Has anyone ever tried 3D printing a shroud for male pin headers? I suppose printing it such the holes are a fraction smaller than the pins, heating the pins with a hot air gun, then pressing it down might work... /shrug
soviet9922
Veteran Member
Doing the 62-pin slot to isa is fairly easy i have done it myself to my system to install an XT-IDE and works great.
You only need a flat ribbon cable having the 64 pin connector they sell them on ebay for pennys, cut the cable and solder an isa slot.
The ram card is so look up because it not only contains the ram (you are stuck on 128k if you don't have it) but also contains the DMA chip and is a necessary addition if you want good compatibility to ibm-pc software.
You only need a flat ribbon cable having the 64 pin connector they sell them on ebay for pennys, cut the cable and solder an isa slot.
The ram card is so look up because it not only contains the ram (you are stuck on 128k if you don't have it) but also contains the DMA chip and is a necessary addition if you want good compatibility to ibm-pc software.
eeguru
Veteran Member
Which are you referring to is the necessity for compatibility? The extra RAM or the DMA chip?
soviet9922
Veteran Member
I'm not sure if installing just a memory card like the guys of the xt ide designed that provide 1 mb could work usign the isa adapter, but the DMA chip is a must to get full XT ibm compatibility.
eeguru
Veteran Member
I call complete BS. Please elaborate... The ISA interface on both Tandy ISA, Tandy PLUS, and PCjr sidecar replaces IRQ6/7 with CPU bus request and ack allowing the addition of an 8237a on a card. None of the machines use DMA for memory refresh. Once installed, the Tandy machines allow DMA operation of floppy (DRQ2). I believe some people here have proven there is BIOS support on Tandys for the upgrade as floppy speeds increase and there is less time interrupts are masked. Tandy machines then support operation of DRQs 1 and 3 from add-on cards (ISA and PLUS). PCjr then allows DRQ0 to be used by a side-car. I'm not aware of any PLUS or side-cars that use DMA unless you can enlighten me.
Sure, if you want to use a ISA sound card in a Tandy 1000A on DRQ 1 or 3, your statement is accurate. But the presence of an 8237A has nothing to do with full IBM compatibility.