[Coco] Coco Flash

[Allen Huffman]

> On Apr 24, 2017, at 7:05 AM, Robert Gault <robert.gault at att.net> wrote:
> 
> Actually HDBDOS is not limited to 256 "drives" but is limited to multiples of 256 "drives" depending on the size of the hard drive. All you need do is POKE values into $D938-$D93A to change the sector offset to the Basic partition of the drive you want to use.
> That means if you add $27600 to the current values you can get another 256 "drives", if the hard drive is large enough.
> 
> I don't know if the capacity of the CoCoSDC is large enough to permit this.

And, it doesn't have to be multiples of 256 if you understand what is going on. The SyQuest EZ135 (128 true MB) had enough room for 416 disks, so on drive #0, I had a small .BAS program I wrote that would ask if I wanted First or Last bank. It would then do the POKEs for me and move the offsets.

First bank was 0-255 at the front of the drive, second offset was 0-255 (physical 160-416) at the end of the drive. I would just put the same disk image on 0 and 160, so "DRIVE 0" would always get me back. I liked the overlap because then I could copy things back and forth using the drives that appeared in both.

But, the program also had the option of doing a true bank, so you would have 0-255 at the First, then 0-160 at the second, no overlap.

That's how I used RGB-DOS for years. I think some articles I wrote about the EZ135 in "the world of 268 micros" covered this.

		-- A