Re: C128 memory - B series compatibility - Basic using 256k - a new version of the hardware for 256k

From: smf <smf_at_null.net>
Date: Mon, 7 May 2018 19:56:17 +0000
Message-ID: <b81f9580-b143-1ef6-96a5-a52c495901e7@null.net>
I believe....

Writes to PCR registers are the same format as the CR register, you 
write to them but mapping doesn't change until...

Writes to LCR register tells it to load from the corresponding PCR 
register into the CR register. It's so you can quickly switch between 
banks without having to keep calculating the CR register or passing it 
around.

So PCRA can be the CR for where code is, PCRB could be the CR for where 
the kernal reads/writes from. The kernal then only needs to know to hit 
LCRB, perform the access and hit LCRA.

On 07/05/2018 19:31, Jim Brain wrote:

> https://ia801002.us.archive.org/10/items/Compute_s_Mapping_the_Commodore_128/Compute_s_Mapping_the_Commodore_128.pdf 
>
>
> I see the registers, but I'm not sure I understand the PCR and LCR 
> regs.  Is there a document that explains these?
>
> Jim
>
>
Received on 2018-05-07 21:02:27

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