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Tandy 1000 series and EMS Memory

Z

Zombie

Experienced Member
Joined
Apr 22, 2011
Messages
125
The Tandy 1000 series tended to lack an A20 handler on the motherboard. Even if you could put larger chips on the 1000 series, like my TL, no A20 gate means no XMS, so has anyone considered what would be involved in creating a modern XT EMS card the same way that Hack-A-Day and Jeff Lyda created the XT IDE Card.
 
Zombie said:
The Tandy 1000 series tended to lack an A20 handler on the motherboard. Even if you could put larger chips on the 1000 series, like my TL, no A20 gate means no XMS, so has anyone considered what would be involved in creating a modern XT EMS card the same way that Hack-A-Day and Jeff Lyda created the XT IDE Card.
Click to expand...

Do you want EMS or XMS? EMS cards should work fine.
 
Vintage EMS cards cost hundreds. Has there been a project to create new ones?
 
I have PCBs for an ISA eval platform on order that should be here at the end of May. It has a 32MB SDR DRAM chip, 2x 512KB SRAMs, 2x 4MB SPI flash chips, couple RS-232 drivers, Super-I/O, and a USB controller interfaced to ISA through a large CPLD and small FPGA. Should allow for testing some interesting possibilities. XMS/EMS expansion was on my list of things to try. Starting new job next week though. So not sure how my time will be.
 
Zombie said:
Vintage EMS cards cost hundreds. Has there been a project to create new ones?
Click to expand...

EMS has nothing to do with A20; that's XMS. I found a couple of EMS-capable cards on eBay for $100 or less. Remember that almost all 8-bit EMS cards are LIM 3.2 at best.

So what will you do with an EMS card?
 
Expand the Memory of my Tandy so that I can keep the network stack used by the Tandy in memory persistently
 
Well, that will work--you save about 100K or so using DOS networking that way.

I've got an Intel Aboveboard/286 on an XT (the AB will work on an 8-bit bus) with 2MB installed.
 
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