AX2000 PLUS (Australian Megachip)

[Amiga87]

Hi all,

I have a AX2000 PLUS, an Australian designed 'megachip' by S.E. Watts Electronics, circa 1992. I am chasing a user manual or additional information for this device.

It's got:
- 8372 2MB Agnus
- 2MB (not 1MB) on-board RAM

Unlike the well know 'Megachip' with 1 jumper wire, it has three jumper wires:
- J1 (yellow) M68K, pin47 (A19)
- J2 (yellow) M68K, pin48 (A20)
- J3 (green) Gary Pin 32 (~EXRAM)

It also has three 3-pin jumpers:
- JP1, default pin 1-2 shorted, 2-3 open
- JP2, default pin 1-2 shorted, 2-3 open
- JP3, default pin 1-2 shorted, 2-3 open

In this default configuration it does not use the Amiga main-board chip RAM. Great for working out if you have issues with chip RAM or address and data buses.

Speculating that J1 must be provided to save setting the jumper on the Amiga main board for A19. J2 is the extra address line to Agnus which is standard on all 'Megachip' implementations I have seen.

J3 which goes to ~EXRAM is interesting. My hypothesis is that it allows the on-board RAM to be used as slow RAM if using the main board chip RAM. But that must be configured by a combination of setting J1, J2 and J3. I speculate an 'addram' command will also be required to enable this additional RAM. Following traces on the links is not much help as they go into the GAL.

If anyone has any extra information on this board it would be much appreciated.

[CyanPixie]

Hi, did you get any more info on this? I have recently come into possession of one of these and am looking for info too

[Amiga87]

Hi, no more info gained, but the above details should be more than enough to get you started with the ax2000.