Re: Switchless ROMs

darn threading email clients, I didn't read that what I wrote had 
already been covered in another part of the thread.

I'd also forgotten that vic doesn't have a reset line. With all the 
extra lines and logic required to detect reset vector fetching then it 
would be better to have a reset header on the rom that could be wired up 
to the cpu reset if you wanted that functionality.

On 28/12/2016 11:37, smf wrote:
> On 27/12/2016 14:03, bwack wrote:
>
>> Interesting approach. Regarding the detection of $fffe on the address 
>> bus, I
>> suppose a MCU can do that.
>
> The rom will only see 0x1ffc/1x1ffd as it only has a0-a12 and I assume 
> /CE only goes low when you're accessing the rom and you just see the 
> address bus change for other addresses.
>
> It's made more complicated because VIC and 6502 share the bus, I don't 
> know if a VIC bad line can split the reset vector fetching. Maybe not 
> when actually resetting as VIC will be reset too, but JMP ($FFFC) 
> might be affected.
>
>
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