mestona@cutmcvax.OZ (meston anthony) (06/09/90)
I have an _OLD_ A2000 (you know, not the B2000) that has 512k chip on the main
mother board. (sob..) The machine has a memory board in the CPU slot with 512k
soldered, and sockets for another 512k AND.... FIVE JUMPERS... I found some
memory and put it in. The only way that the computer would count 1 meg of
$C00000 memory was by swapping jumpers. Not good. This works fine for
everything _EXCEPT_ that a keyboard reset causes RAD: to suicide. Nothing else
in the $C00000 memory seems to be touched (ie guardian..) but the RAD: gives
Read/Write Errors (Grr..). When I examine RAD with a disk editor, there is a
single bit set near the start of some sectors causing a checksum error.
This only happens after a hard reset. A software reset such as issuing the reset
intruction or post-crash reset doesn't cause this. My guess is that the Board
stops refreshing the ram during the reset which causing bit changes! (but why
only RAD: and not other kicktags???) Any help would be appreciated!
Next Question:
What are all the jumpers for?? A diagram: ( : means open, O means closed)
before (as shipped): 12345
:OOO: (component side up, edge conn down V )
after (my guess): 12345
:O::O
Apart from the reset problems, this seems to work.... (but I still want to know
what I have done..)
Final question:
At a local developers meeting, One of the people said that this board is
supposed to be able to overlay the kickstart roms with ram??? yes? no?
If this is possible, this would be MOST USEFUL!!!
From my experiments, this seems likely, because in the A2000 (note: _A_) the
custom chip registers are mapped over $C00000-$DFFFFF and this board overlays
the mapping. (ie writeing to $D00180 is the same as $DFF180 (or $C00180 with the
board out..)) It seems logical that overlaying the rom would be done the same
way. (on the A2000, *OVR can override anything..(I Think..)) But how are the
^*%%&$ing jumpers set up for this??? :-)
By the way, the developer support in Australia is terrible. That is if you can
even get to be registered!! An example: One person over here has written a
laser projection package, and all driver software. You can paint pictures
like dpaint III and use cell animation and project it onto anything from
walls to clouds in the sky. He was not able to get developer status when he
needed it and still can't. With support for the amiga in Australia like this,
it is no wonder the ST is starting to make a comeback over here.....
Ok, enough of my whining! :-)
--
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------- Who me?? That?? No, That is just terminal line noise!! --------
-----------------------------------------------------------------------grr@cbmvax.commodore.com (George Robbins) (06/12/90)
In article <145@cutmcvax.OZ> mestona@cutmcvax.oz (meston anthony) writes: > I have an _OLD_ A2000 (you know, not the B2000) that has 512k chip on the main > mother board. (sob..) The machine has a memory board in the CPU slot with 512k > soldered, and sockets for another 512k AND.... FIVE JUMPERS... I found some > memory and put it in. These boards were made as a stopgap when it was decided that the A2000 should have 1M total memory, even though the PCB only only had provision for 512K of memory. Adding memory to the additional sockets isn't supported and tends to not work especially well. You're better off just getting an Commodore A2058 or equivalent 3-rd party memory expansion. If your expansion card works reliably keep it, otherwise yank it and stick more chips in the Zorro expansion card. -- George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr but no way officially representing: domain: grr@cbmvax.commodore.com Commodore, Engineering Department phone: 215-431-9349 (only by moonlite)
hamish@waikato.ac.nz (06/13/90)
In article <12579@cbmvax.commodore.com>, grr@cbmvax.commodore.com (George Robbins) writes: > In article <145@cutmcvax.OZ> mestona@cutmcvax.oz (meston anthony) writes: >> I have an _OLD_ A2000 (you know, not the B2000) that has 512k chip on the main >> mother board. (sob..) The machine has a memory board in the CPU slot with 512k >> soldered, and sockets for another 512k AND.... FIVE JUMPERS... I found some >> memory and put it in. > > These boards were made as a stopgap when it was decided that the A2000 should > have 1M total memory, even though the PCB only only had provision for 512K of > memory. Adding memory to the additional sockets isn't supported and tends to > not work especially well. > > You're better off just getting an Commodore A2058 or equivalent 3-rd party > memory expansion. If your expansion card works reliably keep it, otherwise > yank it and stick more chips in the Zorro expansion card. > Hmmm... I know many people who are stuck with the old Rev 4 motherboard, that has the discrete agnus chip (ala A1000) and they all have the extra 512k of RAM populated in their machines. Nobody that I know of has ever had any problems with it. I can't remember the positinos of the jumpers, but it has been on the net before. If you can't fins it in the archives send me some email and I'll look under the hood at home. (Mine has one as well). > -- > George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr > but no way officially representing: domain: grr@cbmvax.commodore.com > Commodore, Engineering Department phone: 215-431-9349 (only by moonlite) -- ============================================================================== | Hamish Marson | Internet hamish@waikato.ac.nz | | Computer Support Person | Phone (071)562889 xt 8181 | | Computer Science Department | Amiga 3000 for ME! | | University of Waikato | | ============================================================================== |Disclaimer: Anything said in this message is the personal opinion of the | | finger hitting the keyboard & doesn't represent my employers | | opinion in any way. (ie we probably don't agree) | ==============================================================================