Weird A3000 memory problems

[Castellen]

If you power up the A3000 into just a command prompt and type "avail" then you should have pretty close to 2Mb chip mem if the 2nd Mb of chip mem is fitted.  Try reseating all the ICs from U267 to U274 (the 2nd 1Mb).

If you have a "softboot" ROM where the kickstart is loaded from disk/HD, then the kickstart will permanently eat up 512k of memory, which might explain your problem.

Hold down both mouse buttons on power up, if you see an OS 1.3 - 2.0 selection menu, then you have one of these.


Not sure about the ZIP to SIMM adapator, never seen one before.
There is a single jumper to select which size ZIPs you are using, so try that one.

Obviously you need to make sure you're using the right kind of SIMMs and each pin is socketed properly.

I doubt if it'll work if you have any fast memory in the DIP sockets just to the front of the ZIP sockets, so remove that if fitted.

Also check out:
http://www.feagurth.net/Amiga/A3000Data.HTML

Lots of useful info on A3000s.

[Castellen]

@cv643d
If you have OS 3.1 (ver 40.68) in ROM, then you should have a full 2Mb of chip mem after booting with no startup sequence.
If this is not the case, then you might have some kind of software problem with something using the memory when it shouldn't?

Are you running OS 3.5/3.9?  They do the softboot thing as well, so you'll also loose 512k of memory after that happens.

[Castellen]

@ Darrin
There were quite a few Zorro cards which allowed you to expand the fast memory.  A lot of SCSI controllers like the DKB rapidfire and Oktagon would let you add extra memory.
The problem with most of these is that they were only Zorro II, I.E. 16 bit.  The A3000 accesses fast mem at 32 bits wide, so in order to address the 16 bit memory, it has to do two (16 bit) writes instead of one 32 bit write, therefore memory access time is decreased.

I'm pretty sure the Fastlane card was Zorro III, so accessed memory at 32 bits wide.  This card also allowed you to add a LOT of extra memory, providing you can find the now hard to get 32 pin SIMMs.

I'd recommend getting a nice CPU card such as a Cyberstorm mkII.  You can add up to 128Mb fast mem, which of course is full speed 32 bit access.
Note that most CPU boards require a minor A3000 motherboard modification to run (just a wire jumper) which you can probably do yourself if you have some electronics experience and good soldering skills.

I saw a Cyberstorm mk1 on Amibench the other day at a reasonable price, might be worth a look?

Anthony.