[Coco] CoCo3: banking in ROM-Packs

Pere Serrat psergm at gmail.com
Wed Apr 11 13:00:24 EDT 2018

Hi Barry,
I have flashed them with my program ...
The other six ROMs 32k long do work properly

Mind-Roll starts showing bad characters, but knowing it is asking
for RGB/CMP I choose ‘R’ and then goes to the next screen where
I should choose ‘J’ or ‘K’ but it simply hangs, I need to reset to gain 
control again.
Predator is even worst, it opens a wide back screen and does nothing at all.
I have not flashed Robocop as I want to get Predator working before.
They are the same type (banking).

For the 32k ROMs, I flash first the second 16K block and then the first 
The program sets the flash bank for the 1st part (second flashed) and it 
without issues.
For the banking ROMs, I issue a
    lda       #$22
    sta       $ff64             ; to autostart and allow banking (value 
decimal is 34)
and start from the very first flashed part
I suspect it could be that the ROMs I am using are not correct.
I have contacted Henry Rietveld and he said he would send to me another set
of ROMs to try as the first ones he sent to me were identical to mines ...

Thanks a lot for answering and for your explanantion


Previous message
Message: 11
Date: Wed, 11 Apr 2018 12:06:17 -0400
From: Barry Nelson <barry.nelson at amobiledevice.com>
To: coco at maltedmedia.com
Cc: Pere Serrat <psergm at gmail.com>
Subject: Re: [Coco] CoCo3: banking in ROM-Packs
Message-ID: <F215C164-2947-4603-80F4-B22892839790 at amobiledevice.com>
Content-Type: text/plain; charset=us-ascii

What exactly is the issue you have with these ROMs? I have loaded all three 
of these into my CoCo Flash. Predator and Robocop are type 34 roms, banked 
16k. Mindroll is a 32k type 2 ROM if I remember correctly. These are the ROM 
types the CoCo Flash be setup with:

Type 0, 16k or smaller, used to contain DOS ROMs, no cart RQ.
Type 2, 16k or smaller, used for most games, uses cart IRQ.
Type 2, 32k, used for CoCo 3 enhanced games, uses cart IRQ and maps in from 
$8000 to $FDFF
Type 34, banked 16k, 32k or larger, used for a few large games, uses cart 
IRQ, maps in from $C000 to $FDFF, 16k a a time. Mapping is controlled by a 
register at $FF40.


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