The 2.5MB STE SIMM fixer.

=========================



This is a short program that allows you to fit 2.5MB of memory to an STE 
by mixing 256K and 1MB SIMMs.





Why it's needed

===============



The reason you can't mix the two types of SIMM is that TOS 1.6 in the STE 
fails to recognise this memory configuration and incorrectly programs the 
MMU chip. It thinks, in fact, that you have 4MB of memory installed. This 
causes big problems as soon as you attempt to run any non-trivial program 
(e.g. GEM) The symptoms are that your STE gets stuck in a reset-reboot 
cycle.





How it works

============



This program works by reprogramming the MMU and correctly setting _memtop, 
and then warm booting the STE.



How to use it

=============



You must fit the SIMMs into your STE in the following order:



** (back of STE)** 



  |--  1meg SIMM  --|

  |--  256K SIMM  --|

  |--  1meg SIMM  --|

  |--  256K SIMM  --|



** (front of STE)*



Put the SIMMFIX.PRG program _FIRST_ in your auto folder (do this by 
deleting everything in the AUTO folder, then copy SIMMFIX.PRG to it, and 
then copy everything else back into AUTO).



With SIMMFIX first in your AUTO folder, your ST will start, then reboot, 
and should then display a short message detailing the version of SIMMFIX 
and the authors names.



From then on all should be well. This program has been extensively tested 
by David Hoggan on a wide range of software (though few games were 
tested).





Problems

========



Because you have to run SIMMFIX every time you switch on your STE, you 
cannot just switch on and insert any autobooting disk (e.g. Dungeon 
Master, Starglider II etc. etc.) In these cases, you should make a boot 
disk with nothing except an AUTO folder containing SIMMFIX.PRG. Boot with 
this disk, and when the desktop appears, remove the disk. Insert the game 
disk that you want to autoboot. Then hold down Control, Alt and Delete 
together to reset the STE, and the game will boot and run as normal.



Make sure you have (at least) one backup disk containing SIMMFIX.PRG in 
the AUTO folder in case anything goes wrong with your boot disk. If you 
can't run SIMMFIX, then you'll have to open up your STE and remove the 
256K SIMMS, make a new boot disk, and then put them back.





Program History

===============



The SIMMFIX program was submitted to the "Programmer's Clinic" section of 
ST World, the premier UK ST magazine, by David Hoggan. I (Mathew Lodge) 
made a few additions and wrote this documentation for a posting to USENET.





Mathew Lodge

5 May 1990



(JANET address : SOCS18 @ uk.ac.york.vaxa)