Re: ROMs replacement.. solved!

From: Gerrit Heitsch <>
Date: Wed, 17 Oct 2012 17:16:24 +0200
Message-ID: <>
On 10/16/2012 10:43 PM, wrote:
> Now time to think about 27C512 with place for more KERNALS. Since I want at least three (CBM, Dolphin, Jiffy) 512 with some sort of encoder switch will have to do until Michau builds our ultimate ROM replacement board..

Good to hear that the logic itself was sound, just a bit of missing 
copper kept it from working.

Now, for the 27C512 and more kernals... Well it means you have space for 
4 KERNALs in the second half of the EPROM, making it 6 total.

Until you need more than 4, an easy way might be to connect A15 at the 
EPROM to _KERNAL and then use the multiplexer trick again. Meaning if 
_KERNAL is HIGH, you use A14 and A13 of the EPROM to select BASIC and 
Char-Set(s) and if _KERNAL is LOW, you use them to select your KERNAL.

I'll have to think about it in detail...


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Received on 2012-10-17 16:00:13

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