jdg@elmgate.UUCP (Jeff Gortatowsky) (11/19/86)
Don't you hate it when after seeing your posting with all those '>'s in it
you realize you answered your own question in your posting! Well I do.
Sorry to have cluttered up the net. The correct way to use the 010/881
(as many of you pointed out)
combo is to have the FPU decode the function pins (FC0-2) on the 010
looking for the 020's 'CPU space' function code. When I say decode I'm
just being general. I haven't seriously sat down and drawn this up.
Anyways, at that point you write your OWN software to grab LINE-F opcodes
and decode them (this *MAY* be a bear!). Then you use MOVES (Move Space)
and MOVEC (this sets up the correct function code registers etc.) to
shove the appropriate function code out on FC0-FC2, so as to select the
881 while also addressing the 881 registers in their own 'CPU Space'.
Does anyone know if the Amiga will/won't go crazy when it sees 'Cpu Space'
on the function code pins? I seem to remember something about IACK being
renamed to 'CPU Space' with the 020. Then the 020 use Ax-Ax on the address
bus to specify Cpu Space/Iack/BreakPoint etc. Any comments, good or
otherwise?
--
Jeff Gortatowsky {allegra,seismo}!rochester!kodak!elmgate!jdg
Eastman Kodak Company
<Kodak won't be responsible for the above comments, only those below>grr@cbmvax.cbm.UUCP (George Robbins) (11/20/86)
In article <536@elmgate.UUCP> jdg@elmgate.UUCP (Jeff Gortatowsky) writes: > >Does anyone know if the Amiga will/won't go crazy when it sees 'Cpu Space' >on the function code pins? I seem to remember something about IACK being >renamed to 'CPU Space' with the 020. Then the 020 use Ax-Ax on the address >bus to specify Cpu Space/Iack/BreakPoint etc. Any comments, good or >otherwise? > >Jeff Gortatowsky {allegra,seismo}!rochester!kodak!elmgate!jdg The function code pins do not connect to anything on the A1000 board, however they do appear on the expansion connector. As mentioned in another posting, the A1000 simulates auto-vector by reading the interrupt identifiers from the ROM address space, so there is no special decode for the IACK state, just the address the 68000 is specified to put out on the address bus during an int acknowledgment cycle. -- George Robbins - now working for, uucp: {ihnp4|seismo|rutgers}!cbmvax!grr but no way officially representing arpa: cbmvax!grr@seismo.css.GOV Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)