[Coco] [Color Computer] Multi-Pak Question

[Bob Devries]

Robert Gault said:
> Upgrading the multi-pak for Coco3 use will in no way cause a problem with 
> Coco1 or Coco2 use. These upgrades are completely safe regards backwards 
> compatibility.

Actually, that is not quite true. Yes, the modicication will not adversly 
affect the coco 1 or 2, but there is at least one PAK which will not work 
with that mod in place. I refer to the original CocoMax joystick controller 
cartridge. It's address range is right in the address range that is excluded 
by the modification for the Multi-Pak.

--
Regards, Bob Devries, Dalby, Queensland, Australia

Isaiah 50:4 The sovereign Lord has given me
the capacity to be his spokesman,
so that I know how to help the weary.

website: http://www.home.gil.com.au/~bdevasl
my blog: http://bdevries.invigorated.org/

----- Original Message ----- 
From: "Robert Gault" <robert.gault at worldnet.att.net>
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Sent: Saturday, January 31, 2009 8:55 AM
Subject: Re: [Coco] [Color Computer] Multi-Pak Question


> seanrussoct08 wrote:
>> Hi all coco-ers!
>>
>> I have a quick question.  I have a multi-pak 26-3124 that i bought off
>> of Ebay a few years ago and haven't used it much.  I had a friend several 
>> years ago tell me that he thought you could use
>> one of these multi-paks to access more than one device at a time, but
>> i didn't think you could.  Could someone settle this for me? and if
>> yes, how do you?
>>
>> 2nd, if i buy the hardware from cloud9 to convert this to a coco3
>> capable multi-pak, will it never work on my coco2 again?
>>
>> Thanks,
>>
>
> Upgrading the multi-pak for Coco3 use will in no way cause a problem with 
> Coco1 or Coco2 use. These upgrades are completely safe regards backwards 
> compatibility.
>
> My guess is that when you bought the unit you did not receive the user's 
> manual. Because if you had read the manual, you would see that not only 
> can you select the active slot by using the switch on the unit but also by 
> POKEing a value to 65407 aka &HFF7F.
> The manual states to use the following values:
>  Selected slot      Value
>   1                $00
>   2                $11
>   3                $22
>   4                $33
> A more detailed explanation that supplied by the manual follows. The slots 
> are actually numbered with base-0 notation; 0-3. The nominal value used is 
> the slot value for both the msn and lsn nibbled of the byte, thus $00, 
> $11, $22, $33.
> Actually there are two functions being controlled by the value. The msn 
> selects ROM available to the Coco at $C000-$DFFF, while the lsn selects 
> the I/O device responding to $FF40-$FF5F.
> It is not necessary to use the same value for both msn and lsn. So if you 
> had a device (ex. RealTimeClock) in slot 1 and your disk controller in 
> slot 4, you could POKE &HFF7F,&H30 and retain the Disk ROM in slot 4 while 
> doing I/O through slot 1.
> This also means you could read a ROM in an auto-starting pak without 
> starting the pak. Select the slot of the ROM pak using the msn while 
> keeping the lsn at the default 3.
>
> Doing the above is a bit more complex. You would want to use a short ml 
> program and be sure to clear the CART interrupt before returning to Basic.
>
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