[Coco] CocoFLASH Production
go4retro at go4retro.com
Mon Nov 7 21:34:23 EST 2016
On 11/7/2016 8:12 PM, Mark McDougall wrote:
> On 8/11/2016 1:41 AM, RETRO Innovations wrote:
>> So, is there something else needed to support LodeRunner?
> Thanks for the explanation!
> I have to revisit my memory layout; to be honest I haven't yet
> designed how the cartridge mapping was going to work... 4KB banks is
> good, but I was planning on being able to swap in/out smaller windows
> within the upper 32KB address space. Lode Runner uses the entire lower
> 32KB for video memory, graphics data @$8000, code & game data
> @$C000... so I was thinking a 4KB window somewhere to be able to load
> level data - the original Apple II loaded this directly from disk
Well, I'd probably recommend a "bank in, copy ROM to RAM, and bank out"
approach. Splitting the 32kB ROM space into individually addressed 4kB
virtual ROM slots would probably move me beyond my CPLD space. I might
be able to create 4 8kB virtual ROM slots, and use 4 16 bit pointers to
set the bank for each of those slots:
But, that adds to the IO requirements (10 bytes instead of 4), and
requires quite a bit more setup for the simpler case of mapping in a
16kB or 32kB chunk of ROM into the CART space.
I guess let me know. I can try it, if you feel the extra capability is
> And EEPROM for save game data is awesome! I was going to propose a
> 'standard' structure so that games from various authors could
> co-exist, like a tag/header+length for example, or maybe even a
> FAT-type scheme...
I think that's valuable. I'd even suggest an API that hides the EEPROM
medium, so the same api can be used for Darren's solution, and others.
I was extremely surprised that my 15 macrocell homegrown SPI master works...
RETRO Innovations, Contemporary Gear for Classic Systems
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