mozzie, please try this (HDMIUSB)
PicoMite.zip
Greyscale should work and I have reduced the 1024x600 frequency from 252 to 250MHz which is what it was before (gives about 59Hz)

G'day Peter,
Good news, the Gray/Greyscale command now works in all resolutions, tested in mode 3  

Not so good news: 1024x600 still no joy  
For reference:
PicoMiteV6.00.03b2 works:
Main monitor shows 1024x600 @ 60Hz @ 250000khz cpuspeed
Waveshare DVI monitor works
Elecrow HDMI monitor works

PicoMiteV6.00.03b5 + latest download
Main monitor shows 1024x600 @ 30hz @ 250000khz cpuspeed (both)
Waveshare DVI monitor no display
Elecrow HDMI monitor - intermittent sync only

I was also testing on another waveshare HDMI 1024x600 but might have damaged a plug so a bit of repair work to do before trying it again.

Also no real hurry to get this sorted, put it on the "to do" list if it suits  

Regards,
Lyle.

OK - I think I understand the issue

Try again


PicoMite.zip

G'day Peter,
Excellent News, that's fixed it      

All screens now rock solid at 1024x600 @ 60Hz  

Not sure about anyone else but looking at LCD's working at other than there native resolution ends up giving me a headache  

The Waveshare Pico DVI is really clear and bright, just a shame it needs an adapter board to align the HSTX pins correctly.

My thanks again.

Regards,
Lyle.