[Info-vax] OT: COCO stuff (WAS: OT: For MAC Lovers Only :-))

[John E. Malmberg]

On 10/15/2012 7:13 AM, Bill Gunshannon wrote:
>
> Thanks, even with all the problems it has been fun so far. Next on the
> agenda is NitrOS9 on a COCO3 with 512K of memory and IDE disks.  :-)

I think someone mentioned that a program was available the allowed 
NitrOS9 to read and possibly write FAT formatted floppies.

I did a test with a VMS system a while back and determined that the 
TRS-80 Color Disk Basic ROM could read 512 byte sector disks.

As an experiment, I was able to write data on to foreign mounted DDSS 
3.5 inch floppy on VMS and read the first sector using the COCO DISKI$ 
routine.

Normally the COCO uses a track with 18 256 byte sectors.  The ROM 
actually allocates 512 bytes, 256 for a read, and 256 for an optional 
verification.  The ROM software just reads until it gets an end of 
sector notification, so does not care about the sector size.

The ROM only knows how to get at the first 256 bytes though.

For writing, the two 256 byte buffers are also adjacent, and on 512 byte 
sector media, 512 bytes are written.  Again the COCO ROM only knows to 
put data in the first 256 bytes.

So it should be possible to write a program on VMS or other platform 
that will create a COCO disk directory structure and populate it with 
files that an unmodified COCO can read and write for data transfer.

You would have to play games by modifying the in-use sector map because 
there are only 9 sectors available instead of 18.

Regards,
-John
wb8tyw at qsl.network
Personal Opinion Only