Re: MMU prototyping

From: Michael Brant <brant.michael.l_at_gmail.com>
Date: Wed, 23 May 2018 19:46:46 -0400
Message-ID: <CAGJGKwi1pLMytV4y5AmTLC6YOT_d2pkNAY8W9UXn7KiwjVQ_jQ@mail.gmail.com>
But you are a good hack!!!

On Wed, May 23, 2018, 12:48 PM Jim Brain <brain@jbrain.com> wrote:

> On 5/23/2018 4:55 AM, smf wrote:
>
> On 23/05/2018 00:41, Jim Brain wrote:
>
> I guess it depends on what one defines as a "hack".  This unit simply
> engages the GAME line anytime a memory access that should be outside the
> C64 is requested.  I think that is standard behavior.
>
>
> I don't believe you were supposed to change GAME & EXROM dynamically,
> although a handful of projects do for better or worse.
>
> Ah, then I am a hack, in the grand spirit of hacks :-)
>
>
> When aren't you asserting GAME?
>
> _game is asserted:
>
>
>    - PHI2 is HIGH AND
>    - Address[15:12] != 0 AND
>    - Address[15:12] != D AND
>    - the current PAGE!= 0
>
> PAGE is an 8 bit (soon to be 16 bit) value denoting which 4kB page is
> mapped into the selected page of main system RAM.
>
>
> --
>
> Jim Brainbrain@jbrain.com www.jbrain.com
>
>
Received on 2018-05-24 02:01:43

Archive generated by hypermail 2.2.0.