[Coco] Re: [Color Computer] Help for transfering Coco disk to PC

[Phill Harvey-Smith]

Gene Heskett wrote:
> On Friday 25 March 2005 01:18, Sylvain De Chantal wrote:
> 
>>Hi Folks,
>>
>>I've tried to transfer Coco disks (i have about 130) to my PC (AMD
>>Athlon, Win XP) after installing a TEAC FD-55 GFR floppy drive (a
>>1.2meg high density) and using the Coco emulator of Jeff Vavasour
>>(Version 1-15). I did configure the BIOS for the floppy (B: 5½
>>1.2MEG) and configuring the emulator to read the B: floppy, but i
>>still can't read anything.
>>
>>I've cataloged about 90 disks on my Coco and they work fine. So is
>>there another way to transfer Coco disk to a PC ? Oh and i don't
>>have a modem in my PC since i'm using a high-speed modem connected
>>to the USB port.
> 
> Coco's disks are not going to be readable in a 1.2 meg drive, the 
> spindle speed is wrong for starters.  The heads are too narrow for 
> problem B, and problem C is the data rate.

Not tried it with COCO disks yet, but will do at some point ion the 
future, but I have successfully read and written Daragon Disk images 
using both 1.2M and 1.44M drives. But his was however under linux using
custom disk parameters.

> Coco disks are only 35 track SS disks unless you were using os9, in 
> which case the 720k drives were usable.  The 1.2 meg format uses a 
> 500kilobaud data rate, spinning at 360 rpm.  The Coco's used a 
> 250kilobaud data rate, with the disk spinning at 300 rpm.

The disks I read where standard 40 track 18x256 byte sectors. IIRC 1.2M 
drives will also read/write PC 360K floppies which are 250Kbaud 300rpm IIRC.

> You may be able to jumper that drive for 300 rpm, and the right 
> switches in the driver may be able to slow the data rate down, but 
> then can it double step that 96 tpi drive to emulate a 48 tpi drive?
> 
> Lots of problems and you would be far better off to try to find an old 
> 360k drive that would be far less work to make it work.

If you use Linux on the PC this can all be handled by fdparm, which can 
set
the transfer rate, double step etc, realy usefull for reading alien disk 
formats. I can provide details if people want.

I do know however that Windows 2000 and Windows XP will not read 256 
byte sectors as used by the CoCo/Dragon, I have managed to get XP (with 
the help of some code) to read sectors off a Sincair QL disk but that is 
also 512 byte sectors like a PC disk.

Hope this helps.

Phill.



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