#1 Meg Agnus?
17-Oct-92 02:11:58
Sb: #73677-#1 Meg Agnus?
Fm: Dean Brown 72250,2677
To: Ronald B. Romine 70322,1525
Ronald,
The board changes needed to make the A500 a 1Meg CHIP machine is only
to change where the A501 addresses at in the machine. The OS goes out at
boot time and determines exactly how much CHIP RAM is available and
adjusts itself accordingly. As an example, I can jumper an A500 for 1Meg
of CHIP, install a MegAChip board and an A501 and get 2Meg of CHIP RAM. If
I remove the MegAChip and replace it with a 1Meg Agnus I get 1Meg of CHIP,
If I reinstall the MegAChip but remove the A501 I end up with 1.5Meg of
CHIP RAM. With just the 1Meg Agnus without the A501 the machine shows 1/2
Meg of CHIP.
The only configuration you really need to watch out for is a 512K Agnus
in a machine (A500 or A2000) configured for 1Meg of CHIP RAM. If this is
the case the OS sees 1Meg of CHIP but the Agnus can only use 512K of it.
Then when you use all of the real CHIP RAM, the OS tries to use the 'fake'
memory as CHIP with catastrophic results.
Dean
DKB Software