Tandy T100 info

[Allison]

>
>Subject: Re: Tandy T100 info
>   From: ard at p850ug1.demon.co.uk (Tony Duell)
>   Date: Sun, 15 May 2005 22:11:43 +0100 (BST)
>     To: cctalk at classiccmp.org
>
>> 
>> 
>> I just aquired a Tandy T100, really fun little machine.
>> one of the first steps is to exten the ram (24k more is possible)
>
>>From what I remember, the original RAM consisted of little ceramic 
>substrates with 4 off 2K*8 static RAMs soldered to them. There were 
>separate chip select pins for each RAM, all the address decoding was on 
>the mainboard.

Yep and the ceramic carried 4x 5118 2kx8 parts.

>These modules were 0.7" (I think) wide. But it's possible, with a bit of 
>careful bending, to get a normal 0.6" wide IC into the socket. You can 
>put a nromal 8K*8 static RAM into the top 12 pins of each side of the 
>socket (wiith pins 1,2,27,28 of the RAM haning off the end) and most of 
>the signals match up. I did this in my Model 100. I then did some 
>cut-n-jumper mods to get A11 and A12 straight off the address bus, to 
>modify the address decoder appropriately (while still keeping the 
>original 8K module in the lowest address possition), and to handle the 
>power-down memory protection.

You can but it's ugly.  I need a clean schematic that I can read 
to manage my hack.  I have 8kx8s and 256kx8s aplenty.  


>I should still have notes on this, but I was working on a UK model, which 
>doesn't have the intenral modem, and where different sections of ICs are 
>used in some positions (what I mean here, is that if the US schematic 
>shows, say, U6a as a '00 NAND gate in some position in the circuit, then 
>the UK version still uses a '00 NAND gate, but it might well be U21c (the 
>component references are totally ficticious here!)).

Thats why I need a clean schematic.  The one I have you can't read part 
or pin numbers on. Signal names are just blobs.  A better schematic 
and it's easy as pie.

Allison