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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: asrael22 on July 14, 2019, 06:05:50 PM

Title: Burning ROM for A1200
Post by: asrael22 on July 14, 2019, 06:05:50 PM

Hi.

I'd like to burn ROMs for A1200.
I've read somewhere that A1200 is relatively flexible but Exec must be able to handle it.

Does it work to use only one EPROM 27C800 and burn the complete ROM on it?
Or must it definitely be two EPROMs (hi, lo)?


Manfred

Title: Re: Burning ROM for A1200
Post by: TribbleSmasher on July 14, 2019, 06:11:42 PM

Yes, it must be two ROMs, as the hardware access to it is splitted to odd/even bytes of the ROM. Or something like that. :)

Title: Re: Burning ROM for A1200
Post by: RetroPassion on August 31, 2019, 09:23:03 AM

The 2 ROM's are required on the 1200 :-) seeing that the 400 eproms are cheap anyway. the 800 you use for the CD32.

:-)

Title: Re: Burning ROM for A1200
Post by: thebajaguy on September 04, 2019, 04:43:56 AM

The A1200 reads from the second 256K of each 512K 27C400 EPROM.  This puts the OS image in a place to then appear at $F80000, and the lower 256K of each ROM is left disconnected from appearing (it would show up at $F00000, but that's not permitted).