for Atari XE Game System

This page is dedicated to:
"How to build 1MB RAM expansion into Atari XEGS (XE Game System)".

It contains only few pictures for basic steps! This does not include all steps needed for building it.

Main page about our 1MB SIMM RAM expansion is here.

Photo of XE GS with 1MB RAM is here [495kB].

Here is some photos of how to build it into computer:

XLSMMMU pinout.

Warning! This is special XL version of SMMMU with diferent pinout in comparison with standard SMMMU!

Cut 4 traces at back of motherboard.

At first cut this two traces.

Next cut this two traces.

Put chip socket for XLSMMMU on PIA chip. A chip socket is used to protect the XLSMMMU chip. Connect this 7 pins:

Chip socket pins:	Pia pins:
5	11
6	12
7	13
8	14
9	15
10	16
11	17
others	not conected

In next as first connect pin 12 of XLSMMMU chip socket with GND (left pin of C47 on picture). As second put new capacitator 100nf and his one pin connect at pin 24 of XLSMMMU chip socket and second at pin 12 on same chip socket.

Connect pins of XLSMMMU chip socket with Antic (U8) and chip U12.

Chip socket pins:	On board:
2 (yellow line)	Antic pin 19
3 (purple line)	Antic pin 20
13 (blue line)	chip U8 pin 11
16 (red line)	chip U8 pin 6
17 (green line)	chip U8 pin 18
24 (brown line)	Antic pin 21

XRAM - (eXtended RAM test)
If you want testing your memory extension, you can use XRAM. With this utility you can test all memory extensions from 0 to 4096kb.

Last update: 19.7.2009 Version 1.00