What A2000 MoBo can have 1MB chip RAM ?

[Zac67]

All but the very first A2000(A) mobos can run 1 MB chip. The old mobos are easily recognized by their DIP (long) Agnus, all newer ones have a PLCC (square) one.

As melange stated, you need an ECS Agnus (numbers vary) and to reset a jumper. AFAIK 8375 will work.

[Zac67]

I very clearly remember getting 8375 as 'ECS 1 MB Agnus' directly from C= - stating that 'this is the follow up model'.

Unfortunately the model numbers are not that straight forward.  There have been several, serious attempts to build a table, please use the search function.

PS: Here's alexh's thread from last year - very good info: http://www.amiga.org/forums/showthread.php?t=20895

[Zac67]

Yes. Since the A2000 - or A2000A - officially: Rev 4.0 - was built based on the A1000 OCS, there's no way to expand it to 1 or even 2 MB chip - other than swapping the board with a later rev.

The A model was designed in Germany and was basically an A1000 plus the Zorro backplane base design. When the better Fat Agnus for the A500 was designed, the guys in West Chester designed a new & improved B2000 (Rev 4.1+) that also featured the Buster (the German A2000 had lots of discreet logic there).

[Zac67]

Well, there is this:

http://amigahardware.mariomisic.de/cgi-bin/showhardware_en.cgi?HARDID=967

(old statement, but still)
No, there isn't. The Ranger mem card you pointed out is real $C00000 fast RAM and it's got nothing to do with chip RAM. Sorry.

[Zac67]

Opening J500 will NOT disable the clock.

Even the SM states this (probably the source anyway), but deactivating _EXRAM will just remove the RAM at $C00000 and has nothing whatsoever to do with the RTC.