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384k memory expansion?


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#1 luckybob OFFLINE  

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Posted Fri Jan 12, 2018 6:57 PM

I recently came across an IBM Eduquest, and with it came a memory card of sorts.  It was a blurry Craigslist image, but it was a memory card of some description.  I got the package today and realized it was not IBM.

 

If fact, I'm thinking it is somehow for the ti-99/4a.

 

So that's why I'm here.  I'd love to know what it goes into.  It does have some markings on the PCB, but google comes up with nothing relevant.  The big chip is a TMS 4500A, with a 8445 date code.  The ram chips are all 64kbit, and thus total 384KB.  I looked up the spec sheet of the 4500a and it seems to be pretty universal to any processor.  8086,Z80,68000,TMS9900...  Hopefully it is obvious why I'm here asking.  The extension card is just that, but has 30 contacts on each side, and if I'm not mistaken, that's is the same as the PEB bus.  I'd almost insert it into my PEB, but there is no voltage regulation on the board, so I haven't.  I just bagged it and went asking here for help.

 

UiKPEFKm.jpg?1fcGkSfWm.jpg?1

 

The extension card is exactly that, with a stylized "R" at the top with memory bus, made in taiwan, 3000-0004, and san hua tien co 94v0 on the rear.

 

The main card is just as descriptive.  it is labeled 3000-0003 rev. 2, and A2100-000.  First thought was Amiga 2100.  That was a quick dead-end.  

 

If anyone knows what this goes to.  I'd love to know!  Thanks!


Edited by luckybob, Fri Jan 12, 2018 6:59 PM.


#2 Schmitzi OFFLINE  

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Posted Sat Jan 13, 2018 3:36 AM

bump



#3 Stuart OFFLINE  

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Posted Sat Jan 13, 2018 3:57 AM

No voltage regulators means it is definitely NOT for the TI PEB.  ;-)



#4 RXB OFFLINE  

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Posted Sat Jan 13, 2018 5:03 AM

I had something like that I got from a Electronic Surplus outlet, it was a bubble memory board and powered by huge power unit with RS232 interface.

 

It was slow as hell and like a tape required you to rotate thru entire thing to get back to the same location.

 

Over all it was no faster then Cassette.



#5 luckybob OFFLINE  

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Posted Sat Jan 13, 2018 12:16 PM

No voltage regulators means it is definitely NOT for the TI PEB.  ;-)

 

 

I kinda figured.  Worst case scenario I have a little stockpile of 64kb ram chips.  :P



#6 mizapf OFFLINE  

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Posted Sat Jan 13, 2018 12:25 PM

Isn't 384K just what is needed to expand memory from 640K to 1M? This may well be an early IBM memory expansion.



#7 luckybob OFFLINE  

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Posted Sat Jan 13, 2018 4:51 PM

not exactly.  That last 384k usually has things like vram and roms.  I have many different memory expansions for PC, and it's basically done with a bit of glue logic not a chip even close to the level of the TMS4500A






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