[Coco] Altera DE1 CoCo3FPGA

Robert Gault robert.gault at att.net
Wed Oct 20 20:42:06 EDT 2010

John Kent wrote:
> Hi Robert,
> Yes, basically I was asking how to mount disk images under drive wire.
> The CoCo3FPGA project is an FPGA (Field Programmamble Gate Array)
> implementation of the CoCo3 which has the hardware for the CoCo, GIME,
> VDG, CPU chips and all that programmed at it's basic logic level in
> Verilog and VHDL. Gary Becker designed all the video and keyboard logic
> and so on and I designed the CPU core.
> It has been implemented on two FPGA boards, the Digilent Xilinx Spartan
> 3 starter board and the Terasic Altera Cyclone 2 DE1 board. The
> CoCo3FPGA is implemented entirely in silicon and does not have floppy
> disks as such. It runs on drive wire over an RS232 port. I've noted some
> post on this list regarding it, so I assumed that members of the list
> were familiar with it.
> I assumed the the BASIC ROM included some basic file management
> functions such as listing the files on the disk and loading and saving
> files but I guess that depends on the version of the ROM. I was
> wondering if there were any documents that covered the basic files
> commands of the CoCo. I didn't want to have to wade through the assembly
> code of the BASIC ROMs to work out what was going on.
> I would assume that the drive wire interface would allow a disk image
> from the PC file system to appear as a virtual floppy disk drive. The
> floppy disk image file used on the PC would be selected by the server
> software on the PC and the disk image appear as just another disk drive
> on the CoCo. i.e. just a tunnel between the PC and the CoCo.

Exactly right!

> What I'm not familiar with is the BASIC commands for accessing the
> floppy drives.
> John.

All the commands for Drivewire that are not standard for a Coco disk ROM should 
be found in the documentation at the Cloud-9 site; http://www.cloud9tech.com/
Try looking under Software/Drivewire/documentation although you may be able to 
use a different route.
You want the commands for HDB-DOS/Drivewire.

As far as the standard Coco disk commands, look for the Tandy manuals on the 
Maltedmedia site; ftp://maltedmedia.com/coco/

More information about the Coco mailing list