Amiga / ROM

[Doobrey]

Why won't A4000 ROM3.1 work in A1200 if they both are 32bit?

which one use 256Kx16/512Kx8?

It's got nothing to do with the machine being 16 or 32 bit, but the differences of the machines.. eg. IDE control registers at different addresses etc, small differences in the autoconfig code etc.

The a1200,3000 and 4000 have two 256x16 chips, the a500/600/2000 has one 512x8.

[Bandaid]

The A4000 3.1 ROMs in particular likely won't know anything about the PCMCIA slot in the A1200.  Very important if say one were to use a compact flash card with PCMCIA adapter to copy Aminet archives to the A1200 in a speedy manner. :-)
(Using the above-mentionned driver from Aminet of course)

BTW, does anyone recall whether the A4000 ROMs contain 68030+ instructions that would choke the 680EC20 in the A1200?  Perhaps involving the data cache in the '030 and the lack thereof in the '020?  Just wondering.  Its been years since I read Moto's 68K family docs.