[rescue] LCD hi res 17" monitor wanted

Romain Dolbeau romain at dolbeau.org
Mon Mar 11 18:30:55 CDT 2019

Le lun. 11 mars 2019 C  23:26, Mouse <mouse at rodents-montreal.org> a C)crit :
> I don't suppose you have any doc on how tolerant the chips are?  I've
> been thinking of hacking on the cgsix driver in the NetBSD I use to
> support resolution changing, but I have been hesitant to do anything to
> the hardware that the FORTH code doesn't, since I don't know how
> tolerant it is.

The important chip is the ICS1562A clock chip, which is programmed by
the "setup-oscillator" function on the TGX ROM. That's the one that
needs fixing for alternate frequency. Documentation should be online,
if not I have an archive with my code.

Many alternate resolutions are programmable _without_ touching this,
however, as explained in the Framebuffer FAQ, you just need to
translate the clock parameters to the proper syntax, e.g:

( low-freq 1920x1080x55 using standard 135 MHz clock, work on Iiyama E2473HS
: r1920x1080x55 " 135000000,61058,55,20,251,20,1920,6,6,18,1080,COLOR,0OFFSET"

But some modes needs a clock not in the list supported by the ROM, so
you just reprogram the clock chip... should be completely safe, at
least in theory :-) That's what I need for UXGA, 1600x1200 on a CRT.

>From last time:

I'll send you an archive of my code later, machine is not on right now.

> Also, does TGX+ versus TGX matter for this?

The TGX only has 1 MiB of RAM, so you can't go above 1152x900, but the
same trick is usable to output lower resolutions (e.g. the 1024x768 or
800x600 from older PC CRTs), with a standard or a custom clock, I
suppose - just need to check the clockchip is the same...


Romain Dolbeau

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