MEMORY EXPANSION

                           Memory Expansions,
                   Article for the D.B.A. Magazine 3
                      Written by Eagle of Sentry

As You may know (or not yet), I am a 68000-Coder on the ST(e). In August
1991 I bought myself a 1040 STE. It was perfect, I got myself a Blitter,
1Mb memory, 4096 Colors, Stereo Sound and a TOS v1.62!
So I started coding on the STE. But after month of coding on a 1Mb Atari
with Turbo Assembler, I wanted more memory. Turbo Assembler leaves You
with 212Kb of coding memory when the debugger is installed.

So on the last fair of 1991 in Eindhoven, I intended to buy two 1Mb 9-bits
SIM carts for my STE. But when I had the cards in my hands, I saw that
they sold programs to use 2.5Mb on an STE! I found that rather strange
because a normal ST can work with almost every memory configuration You
put into it. So I stopped the transaction, because the program cost
Fl. 30,-. So I decided to go to Atari first to ask what that 2.5 Mb story
was all about. 
The Atari agency told my that the intern STE hardware could not possible
control 2.5Mb. And even if I bought the program with the memory it still
would not work! So I went back to the firm who sold these 2.5Mb programs
and told the Atari story. The seller immediately tried to sell us a copy
for Fl. 20,-. I decided to buy the 2Mb without the program. But a friend
of of mine decided to buy the program anyway.

At home I inserted the two Sim-carts in my computer, the four Sim-slots
in an 1040 STE are near the power supply. With a 1Mb configuration, thats
when You buy the computer, all the slots are filled with 256Kb-carts.
So You have to remove two 256Kb-Sims first if You want to expand.
The slots look like this from above:
                        ---------------------
                        |    Bank 1 High    |
                        ---------------------
                        |    Bank 2 High    |
                        ---------------------
                        |    Bank 1 Low     |
                        ---------------------
                        |    Bank 2 Low     |
                        ---------------------

So as You can see You have to remove the even Slotpositions, because
in both slots of the same bank must be the same amount of memory.
After I had put the 2Mb in the first bank and left the 512Kb in the
second bank I turned on my computer. It worked perfect!
So I tested some programs, Crash! What the fuck is this! I Booted up
again with the Eagle Utility Disk #2 and checked the computer with
Sysinfo from my friend Wham. It gave a 2.5Mb chip configuration!
But the gave 4Mb of memory!!! So I now knew what the problem was, the
computer hardware was perfect (unlike Atari said), but IT WAS A TOS
ERROR! So I debugged my TOS 1.62, and Yes it checked the first bank and
took it for garanted that the other bank, if it contained any memory,
uses the same configuration. This means that You could use 512Kb,
1Mb,2Mb or 4Mb.
The only thing to do, to make the computer work with other configurations
is to check for Yourself what chips are in the memorybanks and instal
that memory size for TOS. And so I did. I even put the code in the
Sentry Bootvirus Protector I. But for the ones who want a file-version,
and that are a lot of STE-users (I know cause lots of people ask me for
that program), I decided to write this article for the DBA Magazine and
also write the program to put in the AUTO-folder. The source of this
program is included with this article, feel free to use this. DO NOT
CHARGE ANY MONEY FOR IT, AS I HAVE GIVEN IT TO THE PUBLIC!

Enjoy Your 2.5Mb,  Eagle of Sentry.

(If you want to react, write to D.B.A. so they can send it to me).

