[Coco] Altera DE1 CoCo3FPGA

John Kent jekent at optusnet.com.au
Wed Oct 20 10:47:31 EDT 2010

On 21/10/2010 12:47 AM, Robert Gault wrote:
> John,
> You will need to be more precise with your questions. As asked, "I've 
> forgotten though how to mount disk images under the CoCo BASIC", the 
> question is meaningless.
> A real Coco does not use disk images but real floppies, 5.25 or 3.5". 
> Emulators running on advanced PCs use images and mounting of the disk 
> images is specific to individual emulators.
> I think you want to know how to mount a .dsk image in Drivewire but I 
> can't be sure. If that is what you meant, just start the Drivewire 
> server and click on the slots in the Drivewire image and a window 
> should appear asking for the location of a .dsk, .or9, or .vhd image.
> If you are asking about mounting disk images with the Altera / TerASIC 
> DE1 board, I haven't a clue.
> Robert

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.

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




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