[Coco] Coco flash

[Barry Nelson]

> Ron Klein ron at kdomain.org  <mailto:coco%40maltedmedia.com?Subject=Re%3A%20%5BCoco%5D%20Coco%20flash&In-Reply-To=%3CCANgnoUWU%2BMKuMe8b46%3DRoVtSbLoiPpoi%2BbjmJV2Qq7LMErEQMg%40mail.gmail.com%3E>
> Sun Mar 19 22:39:40 EDT 2017
> 
> For those of you who own a Coco Flash unit, does anyone know how to flash
> ROM images greater than 32K?  I understand the concept about 32K ROMs where
> they need to be split in half and the 2 halves are flashed in reverse
> order.  How would that apply to larger ROMs?  For example, a 64K ROM image
> would be split into 4 equal parts.  In what order are those 4 segments
> written?  How about 128K images?
> 
> Thanks
> 
> -Ron
Well, I don’t just own one, my daughter and I wrote the programming code. :) The CoCo itself only supports up to 32k rom cartridges on a CoCo 3, or 16k on a CoCo 1 or 2, but… Certain cartridges have multiple 16k banks an special hardware to support that. Fortunately the CoCo Flash imitates that very same special bank switching hardware. Unlike a 32k cartridge, which really contains a single 32 rom chip that the software has to write in to 16k chunks because the programming software just can’t write any more than 16k in one pass, these cartridge act like they contain two, four or even more separate 16k rom chips that can be selected. Anyway, here is how to write them:
First, just write the 16k segments in order, no swapping. Then when adding it to the selection menu data statements, add it like this:
“NAME OF ROM”,#of_first_bank,34
Where #of_first_bank equals the number of the first 4k bank that was used in the CoCo Flash when you programmed the first 16k of this rom.
The number 34 in the “type” field of the data statement in the menu tells the CoCo Flash to activate the special bank selection circuit that is needed for this type of cartridge. Look at Buzzard Bait that was preloaded for an example. It is only 32k but uses this special bank switched mode since it is designed to run on a CoCo 1 or 2 that don’t normally support 32k roms.