[Coco] CoCo DLOADM command.

[Tormod Volden]

On Tue, Jan 19, 2016 at 9:31 PM, Barry Nelson wrote:
>  I have recently discovered that the CoCo has two commands that I was previously unaware of, DLOAD and DLOADM. These commands load a BASIC or machine language program respectively from the CoCo serial port! I was wondering if I could write a java loader to send an HDBDOS over the serial port instead of having to load it from cassette? You could then boot strap DriveWire over a single serial cable! What do you folks think? Shall I create a git hub site for this? Thoughts? Comments? Supposedly the command had a bug, but this was fixed as of Color BASIC 1.1.


Maybe of interest, some enhancements I made to Bryan Clingman's DLOAD
server (originally from Burt Mitchell):
https://gitlab.com/m6809-computer-tools/dload-server

For using DLOAD to start HDBDOS, the difficulty is that the server
will have to switch from DLOAD protocol to DriveWire protocol. Either
you will have to somehow add DLOAD support to the DriveWire server, or
let the DLOAD server understand when it should die and let the
DriveWire server bind to the serial port.

The DLOAD protocol is also less efficient than DriveWire, so you might
want to use DLOAD to load a small DriveWire-capable loader, like a
hacked-up DWDOS, and then let this DWDOS load the large HDBDOS.

FYI, I worked on these things for the Dragon 32, which has a broken
DLOAD command - there are no bit-banger routines. I patched bit-banger
routines into the BASIC ROM to make it work [1]. However, since I was
patching the ROM anyway, I went on to make a more flexible and
DriveWire-capable client, "DWLOAD" [2]. I would love to see that
ported to the CoCo as well, although I don't know if there is any
space in the BASIC ROMs to patch it in. The DWLOAD code is at [3].

At some point I also made a DWDOS-like "quick loader" [4] specifically
for loading HDBDOS into RAM over DriveWire, but with DWLOAD it became
obsolete.

Tormod

[1] http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=5&t=4272
[2] http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=5&t=4964
[3] https://github.com/EtchedPixels/FUZIX/blob/master/Kernel/platform-dragon-nx32/dwload.asm
[4] http://archive.worldofdragon.org/phpBB3/viewtopic.php?f=5&t=4224#p8677