[Coco] The perfect mas storage for the coco

[Steve]

Matt's (and others) are designing a replacement for the F.D.C cartridge 
that will work (better) for CoCo.

About two years ago, I was working on a design using a PIC chip to 
emulate the the Western Digital floppy disk controller used in the 
CoCo.  While I never got past the breadboard stage, it did show the 
following...

1) Disk BASIC (and OS-9) could used it without any patching.

2) Even nonstandard (protected) formats will work.  (All Tandy & SRB 
Software protected software would load without any patching.)

3) Improved data transfer speeds. Even faster than DriveWire since the 
data is sent into the CoCo by the way of bytes, not bits.

4) OS-9 drivers could even read/write faster with drivers using extended 
I/O interface that does not use the halt line.

The units that emulate the Floppy Disk Drive unit are not much faster 
than a real Floppy since the data still much go through F.D.C with all 
its I/O overhead.  Yes, there is no wait for seeking the track or 
sector.  But still slower than DriveWire.

The key to the F.D.C. emulator is the data format on the SD card. If it 
truly understands the track format of the floppy then any types of disk 
can emulate for the CoCo.  Be it single or double sided, size of the 
sectors, number of sectors will work.

In my design, I used Track Format file that held the format type for the 
Floppy disk. (The data stored on the floppy would be in other files.)  
Most type files were simple with only one track format in the file.  An 
OS-9 boot disk could have few tracks in a standard DECB format with the 
balance in the extended OS-9 I/O format.  While this not the standard 
.DSK format used by CoCo emulators, a translator program could convert 
the data to this new format.

I've already talk to Matt in the past and told him that he is welcome to 
use my research and any help he wants.

This would be a very good Kickstarter or Indiegogo type of project for 
the CoCo community.

Steve

On 6/26/2013 6:34 AM, Matthew Stock wrote:
> I guess I still don't get why you would stick with just emulating the
> floppy drive, provided that you had the opportunity to replace the whole
> disk controller.  What am I missing?
>
> I'm still working out the kinks, but I've been able to convince my HW
> emulator to handshake properly with the Coco bus, and it is reading and
> writing to the SD card.  I'm going to adjust my disk code to support the
> DMK image format, in large part to help with debugging.  I can't trust I'm
> writing the output correctly yet.  :-)
>
> To me replacing the whole cartridge seems a lot nicer, particularly if it
> drops the overall cost.
>    -Matt
>