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AuthorTopic: Burning ROM for A1200  (Read 944 times)

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Offline asrael22

Burning ROM for A1200
« on: July 14, 2019, 06:05:50 PM »

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)?


Offline TribbleSmasher

Re: Burning ROM for A1200
« Reply #1 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. :)

Offline amigapassion

Re: Burning ROM for A1200
« Reply #2 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.

Offering Amiga 500,600,1200,4000,4000T as well as Amiga 500,1500,2000,3000 recapping services as well as minor repairs.

Offline thebajaguy

Re: Burning ROM for A1200
« Reply #3 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).
Former GVP Tech Support 1989-1993 - Bloodied in the original trenches of the Amiga Wild Wild West.