MSX USB

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By sdsnatcher73

Paragon (1204)

sdsnatcher73's picture

18-10-2020, 17:31

Guys, love these developments (as I mentioned before I a sure Wink). I was wondering how far this could go in the future (one that at least sounds great in my mind). I wonder, could we come up with e.g. OPL4 USB, GFX9000 USB? Basically re-implementing these (and other cartridges) to connect over USB to MSX USB where MSX USB would 'translate' and present the devices as their current counterparts would (notably, some I/O, memory space, etc.).

Just thinking out loud here, don't mind me if this is too crazy Wink

By lintweaker

Champion (312)

lintweaker's picture

18-10-2020, 19:07

Crazy idea Tongue
My guess would be that the poor Z80 cannot sustain the load to get things like OPL4 and VDPs working over USB. At least it would not leave enough room do do anything like games.

By S0urceror

Master (138)

S0urceror's picture

19-10-2020, 23:17

sdsnatcher73 wrote:

I wonder, could we come up with e.g. OPL4 USB, GFX9000 USB?

Through MSX USB we can communicate with every USB device that is out there. The maximum bandwidth is limited to the speed of an IN/OUT operation at 3,56Mhz. At every IN/OUT with 11 wait states, we can push 1 byte so the theoretical maximum is ~300KB/sec. That's without error-handling, usb protocol handling, interrupts and any other stuff you need to do.

The CH376s module we use supports full-speed USB 2.0 at 12Mbps so that is ~1500KB/sec.

So in terms of bandwidth with simple USB bulktransfers we can do quite a lot. Smile Another CH376s module in Device mode on the other side of the cable with an Arduino could drive the OPL4 and/or GFX9000 and we should be good. We could also do something crazy and emulate the device in another computer. oO

By popolon_

Resident (62)

popolon_'s picture

11-11-2020, 20:27

Is there going to be low speed usb keyboards supported behind usb hub?

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