[Coco] Disk Basic and 512 byte block floppies.

[tim lindner]

John E. Malmberg <wb8tyw at qsl.net> wrote:

> After reading about how the IDE was supported on HGB dos, I decided to
> try an experiment with ROM BASIC on a COCO II.
> 
> I formatted a 720K 3.5 inch floppy with 512 byte sectors on OpenVMS 
> because ODS-2 puts some readable ASCII in the first sector.
> 
<snip>

Interesting experiement.

The size of each sector is written to the disk. Disk BASIC expects all
the sectors to be 256 bytes, it doesn't check. It create 256 byte blocks
of RAM to read to and from these sectors.

If the sector is larger, then the RAM buffer will overflow. On a read
sector command you will overwrite whatever is past the sector buffer in
RAM. The could be dangerous.

On a write sector command you will write whatever data is after the
buffer to the larger sector.

-- 
tim lindner
tlindner at ix.netcom.com                                        Bright