New project: vDisk - sneak preview :-)

By lintweaker

Master (156)

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02-11-2019, 10:34

I've finally made my own MSX cartridge! In it's first version it will function as a virtual disk drive where a Rasperry Pi Zero will serve up disk images which can be read from the MSX.

The design is based on smbaker's
Pi virtual floppy for ISA/XT

With this hardware there are lot's of possibilities for future expansion, like using it as a MSX networkcard (with a Pi Zero W),

Now all I need to do is write a MSX Disk BIOS :)
The flash on board (currently not fitted) has a DOS2 mapper and can handle 1 and 2 Mbit flash ROMs.
Using Nextor with a Nextor driver would also be a nice option.

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By sdsnatcher73

Hero (592)

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02-11-2019, 18:12

Cool! We cannot have enough disk replacement options, if you ask me...

By lintweaker

Master (156)

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02-11-2019, 19:12

The more the better :-)
I quick read test using assembly in WBASS2, reading all 1440 sectors of a 720k disk, seems quite good.

By Pencioner

Paladin (955)

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02-11-2019, 22:40

sdsnatcher73 wrote:

Cool! We cannot have enough disk replacement options, if you ask me...

Still, i'm more interested in other possible uses of it Smile Would be useful to have some Pi power to have a collaboration between it and MSX

By ToriHino

Champion (368)

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02-11-2019, 22:57

Pencioner wrote:

Still, i'm more interested in other possible uses of it Smile Would be useful to have some Pi power to have a collaboration between it and MSX

Something like this ?

By Manuel

Ascended (15754)

Manuel's picture

02-11-2019, 23:11

Reminds me a bit of Nowind...

By Pencioner

Paladin (955)

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03-11-2019, 02:00

ToriHino wrote:
Pencioner wrote:

Still, i'm more interested in other possible uses of it Smile Would be useful to have some Pi power to have a collaboration between it and MSX

Something like this ?

Correct. I had big hopes for that one (i have the prototype from first batch). But it has been designed in a way which made programming on both sides quite uneasy, so i'm looking forward for this one

By lintweaker

Master (156)

lintweaker's picture

09-11-2019, 12:01

I am still waiting for parts to arrive so I can verify that the DOS2 mapper part works.

Some more info on the design:
I am using a 2k Dual Port SRAM which can be read and written to from both MSX as the Pi side.
By writing to a mailbox address from the MSX, the Pi is triggered there is work to be done.
I've mapped the 2k SRAM in page 0 in the MSX side, this way page 1 (4000-7fffh) is completely available for BIOS code.

By zPasi

Champion (471)

zPasi's picture

09-11-2019, 18:12

For just a disk drive, a little bit overkill. I bet there is enough power in the PI Zero to handle the whole thing, without the need of other chips than voltage shifting buffers.

Some years ago I made a disk drive / memory mapper thing from an STM32F4-Discovery board. It has 5 V tolerant I/O:s so there is not even voltage shifters.
Picture in Dropbox

However, your new board has potential for much more. Definitely very interesting a project!