[Coco] Design Question
go4retro at go4retro.com
Mon Mar 27 14:01:32 EDT 2017
Not sure if anyone has an opinion, but thought I would ask:
In most (all?) of my Coco designs, I am putting in FLASH ROM support.
This requires, at a minimum:
a bit or two to handle autostart and program mode. (Say 2 bits).
I find that I have two ways to handle this.
Take, for instance, the CocoNIC cart. I could do two things:
* Treat the NIC and the FLASH components as separate things. The NIC
decodes at one base address, the FLASH at another
* Treat them as a single unit. NIC registers follow the FLASH
registers, so to speak (or the other way around).
Advantages of the separated idea:
* Code can be easily written to handle all of the FLASH portions of
each cart, without any regard to what else is on the unit
* nice way to easily add the support to any cart
* Takes a bit more logic to handle
Advantages of combining:
* a bit less logic (15 macrocells, in general
Disadvantages in combining:
* Programming code needs to know more about cart use:
o If NIC, programming regs are *here*
o else, if arduino interface, reg are *there*
* Makes it a bit more work to add FLASH to a cart
* 15 extra macrocells to use for other things.
I am leaning towards maintaining the separation, but thought I would
canvas for opinions.
RETRO Innovations, Contemporary Gear for Classic Systems
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