[Coco] lets play canyon climber from floppy disk ( 8 inch floppy disk)

[Mark J. Blair]

> On Nov 5, 2019, at 8:43 AM, Alex Evans <varmfskii at gmail.com> wrote:
> 
> 8" drives aren't very different from 5.25" drives.  They have an
> additional signal so that for drives that need it you can change the
> signal strength depending on whether you are on the inside or outside
> of the disk, they spin at 360 rpm (like 5.25" HD drives), they
> generally have 77 tracks, and the data rate is doubled (so the SD (FM)
> data rate is what you would expect on DD (MFM) on a 5.25" disk and the
> DD (MFM) data rate is the same as the HD (still MFM) data rate for a
> 5.25" floppy). Basically a DSDD soft sector 8" floppy will look like a
> DSHD 5.25" floppy with a few tracks missing.
> 
> On Tue, Nov 5, 2019 at 9:46 AM Sean <badfrog at gmail.com> wrote:
>> 
>> How is the 8" floppy drive talking to the CoCo?  I thought those drives
>> were way different than a 5 1/4" and not compatible?   I think I can see
>> you have some sort of device in between the disk controller and drive.


Here's an example of an adapter which can be used to connect a 50-pin 8" drive to a 34-pin controller (such as a CoCo's floppy disk controller cartridge):

http://www.dbit.com/fdadap.html

It's mostly just a matter of patching wires around, but that board also has some electronics to generate that additional signal which many 8" drives need to write properly. I wouldn't expect DECB to know how to deal with a 360 RPM drive, but the floppy disk controller chip in a CoCo's disk cartridge is capable of working with an 8" drive otherwise.

Note that I haven't watched the video in question yet, so I apologize if I'm rambling about something that everybody already knows.



-- 
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/