#1Meg Agnus on A1000
4 messages in this thread
For all those doubting thomases out there, I'd like to forever put to rest
the argument that it is impossible to adapt the 1 MEG AGNUS to an A1000 as
this message was composed on a machine with said configuration 🙂
My prototype took three days and a few PAL mods, but indeed after blowing
up a Kickstart ROM, its working fine and I have 936K of chip RAM free!. I
am now proceding to make the more elegant features such as my real time
clock & video slot work. 🙂 🙂 😉
Ok Greg, I'll bite, just what and how did you have to do to get the 1
meggers to run?? I've had my amiga for over 3 years now and really don't
want to give it up for a 500 or 2000 if I don't have to.
Well, to make a long story somewhat short, I realized that the 1 Meg Agnus
could not be interfaced to the motherboard chip ram due to design
diferences. The Fat Agnus is designed to talk to 256Kx1 or 256Kx4 chips
and the old A1000 Agnus was designed to talk only to 16 64Kx4 chips. The
trick was to create a new daughterboard, to replace the WCS (Kickstart RAM)
daughterboard and extend it to the three custom chip sockets. I put 1 MB of
new memory on this PCB, connected to the custom chips (all three are now on
the daughterboard). With careful design, the motherboard RAM, formerly CHIP
RAM, can be made into 512K of FAST RAM (Not yet done).
Other features to be tested are a A1000 video slot (A2000 subset) and OKI
real time clock chip, and with some creative PAL design, turn that 512K of
motherboard RAM into 256K of Fast RAM and 256K Kickstart RAM (ROMS are
currently used).
No trace cuts are currently needed on the motherboard as I sychronize the
Agnus clocks to the motherboard clocks. only two wires are needed to be run
from the daughterboard to the motherboard.
GreG, congratulations. I would like to talk to you about this. 406-367-5509
–Ben-