[Coco] auto-starting game paks

[Roger Taylor]

At 05:28 PM 1/20/2009, you wrote:
>>I'm trying to think of a way connect Q to CART to make an 
>>auto-starting pak, but also use a few logic gates or maybe a 
>>transistor to block the Q-to-CART connection once something in the 
>>pak is On and Ready, such as the 6551 ACIA which also uses CART.  So,
>>  once the CPU interrupts are enabled back by the pak ROM software, Q
>>  will be filtered from entering CART and only the 6551's interrupt
>>pin will affect CART.
>
>The other way to do it, is to have your ROM code have DK as the first

I've already done that for an embedded application put in an EPROM 
Pak.  It works brilliantly, but there's no way to toggle this type of 
auto-start.  It always happens, or at least when ECB is on the 
motherboard.  I was trying to use a jumper and some kind of hardware 
control on the cartridge to let the user decide how to use the 
pak.  Auto-starting RS-232 packs with custom ROMs for embedded 
solutions would be very nice, but probably used by very few.




>characters and the actual code start at $C002, as this is  what the 
>Dos carts for both the CoCo and the Dragon do. Though after they 
>have done their initialisation they do jump back to the Basic rom 
>for it to continue it's initialisation, but a look at the relevent 
>DOS rom disassembilies should reveal where you need to jump to.

As you said, "DK" as the first two characters just causes BASIC to 
software-auto-start the ROM.  But, then you take control and don't 
have to hand it back over to BASIC like Disk BASIC does.  The CoCo 3 
will also patch part of your ROM near the top, and we discussed this 
earlier on how we should move our code out of those areas.  It really 
works nice.


-- 
Roger Taylor

http://www.wordofthedayonline.com