MSX USB

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By sdsnatcher73

Paragon (1507)

sdsnatcher73의 아바타

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 (349)

lintweaker의 아바타

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 (140)

S0urceror의 아바타

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_

Expert (127)

popolon_의 아바타

11-11-2020, 20:27

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

By S0urceror

Master (140)

S0urceror의 아바타

08-12-2020, 21:25

Sorry popolon_, I missed your question earlier.

Low speed as only device is supported. Behind hub means I have to support multi-TT mode and I haven't figured that out yet. The issue is that the rest of the devices are high speed or faster and the keyboard is the only low speed. Hubs support that via multi-TT mode.

By konamiman

Paragon (1098)

konamiman의 아바타

29-12-2020, 15:44

Hi S0urceror, I plan to do some USB related stuff in the coming year and I think it would be great if we could collaborate/coordinate. Is the email address in your profile still valid? (last April I sent you an email that got no reply... but that email was in turn a reply to an email that you had sent me in February, so the whole thing is totally my fault) Big smile

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