[Coco] First experiences with my DE1

[Mark McDougall]

On 18/02/2014 7:52 AM, Nick Marentes wrote:

> Why I don't know. I hadn't flashged the Disk Basic ROM so clearly it is
> included in the CoCo3 ROM image.

The DISK BASIC ROM is patched for Drivewire, and therefore included in the 
FPGA bitstream image as it is contained within the on-chip RAM.

> Now I need to work out how to read DSK images. I copied a DSK file to the
> SDCard but I can't seem to read it. Anyone had experience with the DE1
> reading DSK's?

There is no support for SD card on Coco3FPGA. You need to use Drivewire to 
read/write floppies images on a (PC) server.

Floppy emulation via SD card is actually an involved process and generally 
requires a dedicated soft-core processor, because it involves not only 
emulation of the Coco's FDC, but also modules to read/write SD, read/write 
DSK images, *AND* FAT filesystem support!!!

A lot of FPGA emulations use external micro's for this very reason. Even the 
original Minimg (Amiga 500) used a 2nd soft-core processor for FDC emulation 
(initially a Z80, but IIRC now a 2nd 68K). Both the MiST board and the 
Replay board from FPGAARCADE.COM have an external ARM for this.

Given that the Coco3FPGA uses much of the DE1's resources, it would be very 
difficult, if not impossible, IMHO to add FDC support for SD card to it, 
unfortunately.

It is much, much easier to emulate hard disks via CF, and even SD to an 
extent. Hence the reason my Coco 1/2 uses HDBDOS to read from an SD card.

Regards,

-- 
|              Mark McDougall                | "Electrical Engineers do it
|  <http://members.iinet.net.au/~msmcdoug>   |   with less resistance!"