>Dear Mr. Pelli,dear nicolas
>
>I'm still looking for a video-card able to display 12-bit
>per channel or more on a Mac. During my searches, I found that
>such a card has been developed by Cambridge Research Systems,
>unfortunytely for the PC only at the present time, and at a
>very high price :
>
>http://www.crsltd.com/body/vsg.html#VSG25
>
>But since they also sell a device for generating 15-bit visual
>stimuli that also works on the Mac, there may still be hope.
>Anyway, I thought that this info might interest you. By the
>way, I wish to thank you for the work you put into the
>VideoToolBox : your software is very appreciated !
>
>Best regards,
>
>Nicolas Rudaz
they use two 8-bit DACs added together. this is very similar to the
three-DAC ISR Video Attenuator scheme (which they have used on earlier
products).
Note that to use their PCI card on a Mac would require them only to write
a Mac driver, so the effort is modest. You should tell them that you're
interested because it may not take much to convince them to invest in the
software effort to increase the market for their hardware
thanks for passing this on
best
denis
p.s. The claim of "15 bits" may be misleading, since the accuracy will be
limited by the typically plus or minus half step error in the least
significant bit of the unattenuated 8-bit DAC. However, in situations in
which the unattenuated DAC is not changing, then waveforms passed by the
attenuated DAC (divided by 128) will be accurate to 15 bits, over the
(1/128) range accessible.