At 04:16 PM 03/05/99 +0100, you wrote:
>I want to make a 'driver' for emulating disk-images from a PC to a MSX. The
>idea is to connect a MSX to a PC and then emulate a disk from data that is
>stored on the PC.
I made a diskROM like that which reads DSK images from PC to MSX through
the JoyNet cable. At the moment, it is read-only and works under DOS1
(MSX-DOS and BASIC). I can send you the code if you like. The main problem
with the code is that my protocol cannot recover from errors. The protocol
is constructed in such a way that errors are rare, but they do occur
sometimes (about once in 50 megs).
The PC side is a simple "sector server" written in Delphi. You can select a
DSK image and a volume inside that image (for multi-disk images). It also
reports a disk change signal, which makes caching at the MSX side possible.
>Now, I want to know if I can get away with just writing
>new routines for PHYDIO etc. (i.e. changing the JP's in the diskrom at
>4010h, 4013h etc. to my routines which do the communication with the PC). I
>only want to change the physical I/O part, everything else should then still
>work.
You only have to implement the I/O routines located at #4010 and higher
(get DPB, read sector, disk change, format etc). You don't even need the
other routines, because they are already located in the main diskROM.
Then you need some way to connect your routines to a drive letter. What I
do at the moment is to modify the table located at #FB21, using a CALL
statement in BASIC. What would be better is to have the extra drive added
at boot time. Can someone explain how to do this?
>I want to integrate this diskrom in a cartridge that holds the interface.
I am very interested if you can make a high-speed parallel connection.
JoyNet, which is a simple serial connection, is slow for DSK emulation (a
bit slower than a real drive).
Bye,
Maarten
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