The following document was submitted by Dennis Armstrong.
Thanks to Frank Lockwood for putting me in touch with Dennis.
Upgrading the TT fastram board from 4Mb to 16Mb
The upgrade is for the atari TT fastram board CA400312 which has three jumpers marked W1, W2 and W3.If you have SIPPs which are soldered to the pcb then you will have to obtain 4 SIMM holders. remove the SIPPs from the board by desoldering them and solder the SIMM holders in their place. Be carefull about the correct orientation of the holders.
The pins on the SIPPs can be removed, by desoldering, the resurrected SIMMS can be placed in the SIMM holders and the board replaced in the computer to check that everything is still OK.
step 0. Remove the four 1Mb SIMMs.
step 1. Cut the pcb track between the the 47ohm resistor pack (RP101) pin 1 and the TTFMCU pin 10 (MAD0). There is only one connection between these pins.
step 2. Make sure that pin 19 of the SIMM holders are not connected. Connect each of the A10 address lines of the SIMM holders pin 19 together. and connect this wire to one end of a 47ohm resistor. The other end of the 47ohm resistor is connected to pin 10 of the TTFMCU (MAD0). This pin should not be connected to any other before the resistor was connected.
step 3. connect pin 1 of resistor pack RP101 to TTFMCU pin 73 (MAD10)
step 4. jumper W1 should be connected 2 - 3 (equvalent to jumper W103) jumper W2 should be connected 2 - 3 (equvalent to jumper W104) this gives a starting address of $0100 0000 for the fastram
step 5. Connect a 820 ohm resistor from pin 62 of TTFMCU (*STERM) to +5v (VCC) +5v (VCC) is availiable on the connector J101B pins 37,38,39,40,57,58,59 and 60 or on the TTFMCU (U101) at pins 3,7,12,54,70,75,79 and 83.
step 6. Disconnect pin 52 of TTFMCU (M4X1) from 0Volts (Gnd) and connect to +5V if required (equvalent to jumper W106 on the newer TTram card).
step 7. Insert the 4Mb SIMMs and replace in tha atari.
locations:pin 32 pin 12 ___________________ --------- pin 33 | | pin 11 pin 1| | | | | | | | | | | TTFMCU | | RP101 | | | --------- | | --------- pin 53 | | pin 75 | RP102 | ------------------ | | pin 54 pin 74 | | | | W3 | | W2 _________ W1 | | | | | | | | | | | | SIMMs --> | | | | | | | | | | | |
This has been prepared from the circuit schematics only, I don't have the atari TT fastram board (I bought the GE SOFT one) to check the pcb traces.
If you succeed with the upgrade please post the note to usenet. The TTFMCU is used in both the old (4M) and new (4M/16M) pcbs so this upgrade should work.
../TT RAM