🚀 go-pugleaf

    running an Aerco/E. Arthur Brown 4 megabyte setup with no problems at all;
it's been extremely solid.  You should note though that I'm not using the
Atari power supply; my ST is running off the same 150 watt XT power supply
that runs my hard disks.  If you install 4 megabytes in a "solderless" fashion
into a 520, you'll at a minimum be powering 3 banks of memory chips (even though
only two are being used) which potentially could put a stress on the power supply.

As to the comment about the memory test program supplied by Aerco/E. Arthur Brown
not working; I had that same experience.  I used a public domain memory tester
released by Supra Corp; that handled the 4 megabytes fine.

Using the latest rev of the Aerco MMU adaptor board (you've got the latest rev if
the MMU mounts "upside down") there is just enough room to piggyback a blitter
chip on top of the 68000 cpu (if that turns out to be the ultimate upgrade method...)

dgc