his rom without copyright may come not from a commodore product but from an add-on for commodore for example: serial port connected to IEEE 488 I think the machine is very simple - a 6502 - a ram memory chip (size unknown probably 2k or 4k) - a 1st device (I suppose a PIA in $4000) (perhaps for an IEEE488) - a 2nd device (I suppose a Z80SIO in $8000) (the serial port) - a rom with the firmware (2764 ???) I'll have to explore the code using $4000 and $8000 to confirm that we really have a pia and a z80sio On 27/08/2020 18:45, Martin Hoffmann-Vetter wrote: > Hello, > >> The bytes at $e000 & $e001 are used as data, but also the irq/brk >> vector points to $e000 so any irq or brk will go into an infinite >> loop. > No, $e000 ist only used as defaut value for $0059 and $e001 as defaut value for $006a. > > All hardware vectors (reset, irq and nmi) points to $e002. > >> Reset or nmi will start execution at $e002. > There is a brk at $e864 that is called as error after timeout. So the reset routine is called via irq routine. > > I think this is an eprom for a single mpu system with small address decoding: $0000-$3fff for ram, $4000-$7fff for io1, $8000-$bf00 for io2 and $c000-$ffff for rom. Only first four bytes are used for io1 and io2. > >>> I have 2 eproms labeled: pc-central-26-4.bin (8k) and >>> boot-poste-3.bin (4) the boot-post-3.bin contains the good >>> content... [the copyright is present] >> Are the two roms related? It might help to have them both > Yes, that's a very good idea. Is it possible to post the other rom, too? > > Regards > Martin > > > >Received on 2020-08-28 22:00:03
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