A3046? cpu in A3000?
21-Jan-95 04:04:11
Sb: A3046? cpu in A3000?
Fm: Charles B. McCann 70107,1506
To: John M. Collier 72172,1363
John-
I installed an A3640 CBM 68040 accelerator in My stock 16mhz A3000 several
months ago.
It works very well. However, getting the board and the A3000 built in SCSI port
to function
harmoniously was a nightmare. Also, I consulted with 4 authorized Amiga
hardware techs
before I did this. I got four different answers, none of which were correct
from my experience:
This was what I was told:
1. A3640 Only works in A4000 and A3000Tower
2. Should work. I guess. Yeah, it'll work.
3. Does not work in an A3000. Nope.
4. Works in some and not others. Reasons unknown.
Here is what I did to make it work:
First, I consulted 'Appendix E-1=> A3000 Schematics' in the "Introducing the
Commodore Amiga 3000" Manual.
I noted each jumper with a setting specific to the processor clock speed
(16mhz or 25 mhz NTSC or PAL) and
set the motherboard jumpers to the setting for (NTSC) 25mhz. Maybe 6 or 7 had
to be changed.
The real tricky thing was that thru lots of experimenting a dumb stroke of
luck, I discovered that the A3640 &
built in SCSI conflict could be resolved by using a PageMode Zip in at least
the first (U852) Zip Ram socket,
as opposed to a Static Column Mode Zip. Apparently, Page mode operation
disables burst mode memory caching
something 'er'other that the 68040 chip can use to run even faster, but that
freaks out the
A3000 SCSI.
This was my experience. Yours could be different. Who knows.
PS: Trouble was worthwile. Speed increase is SIGNIFICANT!
GOOD LUCK,
Charlie McC
70107,1506