Re: Switchless ROMs

From: smf <*smf_at_null.net*> Date: Wed, 28 Dec 2016 11:37:29 +0000 Message-ID: <a953c40a-e137-d320-2b49-ff67944b5d89@null.net> · smf_at_null.net

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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