Cybervision 64 vertical refresh rate

trixster · 04 October 2018, 15:12

Hi,

I'm using a Cybervision 64 with picasso96.

At 1280x1024 the maximum vertical refresh rate I can set in Picasso96Mode in 16bit colour is 47Hz. Is this because I set 31khz for monitor type during the p96 installation? Should I have selected 54khz (or greater?)? My monitor is a dell 2001fp which is capable of horizontal 81khz.

zipper · 04 October 2018, 15:56

It might be about the highest that the chip can do (at least without overclocking).

Jope · 04 October 2018, 18:02

I always select the highest frequency monitor type there is in the defaults, then dial the refresh rates down to 60Hz for each resolution.

trixster · 04 October 2018, 19:28

So it looks like the maximum clock a CV64 will manage at 1280x1024 is 85mhz, and 60hz at this frequency requires about 105mhz. So as has been said, the Cv64 ramdac would have to be overclocked to achive 60hz.

Is this correct? Anyone with a cv64 managed 50 or 60hz at 1280x1024?

zipper · 04 October 2018, 20:06

I suppose about 10 MHz overclock might be possible without tampering with the memory so you could get a little over 50 Hz. This gives some suitable hints due to CV64/3D http://members.iinet.net.au/~davem2/overclock/cv3d.html

trixster · 04 October 2018, 20:38

Yeah, I think a 90mhz clock would give 50hz which would actually be fine. The MEMORYCLOCK tooltype does what it says (default clock is 54mhz) but I’m not sure how/if the pixel clock can be set similarly. Will have a read of that link, thanks.

04 October 2018, 15:12	#1
trixster Guru Meditating Join Date: Jun 2014 Location: England Posts: 2,367	Cybervision 64 vertical refresh rate Hi, I'm using a Cybervision 64 with picasso96. At 1280x1024 the maximum vertical refresh rate I can set in Picasso96Mode in 16bit colour is 47Hz. Is this because I set 31khz for monitor type during the p96 installation? Should I have selected 54khz (or greater?)? My monitor is a dell 2001fp which is capable of horizontal 81khz.

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04 October 2018, 15:56	#2
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,848	It might be about the highest that the chip can do (at least without overclocking).

04 October 2018, 18:02	#3
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,955	I always select the highest frequency monitor type there is in the defaults, then dial the refresh rates down to 60Hz for each resolution.

04 October 2018, 19:28	#4
trixster Guru Meditating Join Date: Jun 2014 Location: England Posts: 2,367	So it looks like the maximum clock a CV64 will manage at 1280x1024 is 85mhz, and 60hz at this frequency requires about 105mhz. So as has been said, the Cv64 ramdac would have to be overclocked to achive 60hz. Is this correct? Anyone with a cv64 managed 50 or 60hz at 1280x1024?

04 October 2018, 20:06	#5
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,848	I suppose about 10 MHz overclock might be possible without tampering with the memory so you could get a little over 50 Hz. This gives some suitable hints due to CV64/3D http://members.iinet.net.au/~davem2/overclock/cv3d.html

04 October 2018, 20:38	#6
trixster Guru Meditating Join Date: Jun 2014 Location: England Posts: 2,367	Yeah, I think a 90mhz clock would give 50hz which would actually be fine. The MEMORYCLOCK tooltype does what it says (default clock is 54mhz) but I’m not sure how/if the pixel clock can be set similarly. Will have a read of that link, thanks.

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