leo@zelator.uucp (Stefan Hartmann) (06/02/91)
Hi graphics wizards, Could somebody tell me ,if it is possible to change just the DAC on a ET 4000 VGA-Board to the new Sierra Hi-Color (15 bit) DAC to get the 32768 colors ? Or is there also a BIOS update and another quarz oszillator necessary ?? I have already downloaded some demo programs to show TARGA (*.TGA)-pics from COMPUSERVE , but I wanted this to know first before I simply buy the new Sierra DAC ! Any advice is welcome . Thanks a lot ! -Stefan Hartmann, c/o OverScan GbR.( Manufacturer of the Auto-Switch-OverScan Hardware for Atari ST-Computer) -- ******************************************************************************* * EMAIL: leo@zelator.uucp Stefan Hartmann * * COMPUSERVE: 72017,3216 GEnie: S.HARTMANN * * Phone : ++ 49 30 344 23 66 FAX : ++ 49 30 344 92 79 * ********************************************************************************
n65j@vax5.cit.cornell.edu (06/07/91)
In article <H7HR0NO@zelator.uucp>, leo@zelator.uucp (Stefan Hartmann) writes: > Hi graphics wizards, > > Could somebody tell me ,if it is possible to change just the DAC on a > ET 4000 VGA-Board to the new Sierra Hi-Color (15 bit) DAC to get > the 32768 colors ? > Or is there also a BIOS update and another quarz oszillator necessary ?? > I have already downloaded some demo programs to show TARGA (*.TGA)-pics > from COMPUSERVE , but I wanted this to know first before I simply buy the > new Sierra DAC ! > Any advice is welcome . Thanks a lot ! > -Stefan Hartmann, c/o OverScan GbR.( Manufacturer of the Auto-Switch-OverScan > Hardware for Atari ST-Computer) This depends on the board and is best asked of the manufacturer. One simple thing that could rule out an easy swap is if the existing DAC is soldered to the board instead of socketed. The Compuserve software that takes advantage of this chip tends to rely on the extra BIOS support which Tseng labs defined and which STB implemented even before they started selling boards which included the chip. Thus you may need a BIOS upgrade unless you are into programming the Tseng chip and Sierra chip at the register level. Might be fun, for some. -- regards, Steve Pacenka, Cornell U.
daf@vaxc.cc.monash.edu.au (06/07/91)
n65j@vax5.cit.cornell.edu writes: > In article <H7HR0NO@zelator.uucp>, > leo@zelator.uucp (Stefan Hartmann) writes: >> Hi graphics wizards, >> >> Could somebody tell me ,if it is possible to change just the DAC on a >> ET 4000 VGA-Board to the new Sierra Hi-Color (15 bit) DAC to get >> the 32768 colors ? >> Or is there also a BIOS update and another quarz oszillator necessary ?? >> I have already downloaded some demo programs to show TARGA (*.TGA)-pics >> from COMPUSERVE , but I wanted this to know first before I simply buy the >> new Sierra DAC ! >> Any advice is welcome . Thanks a lot ! >> -Stefan Hartmann, c/o OverScan GbR.( Manufacturer of the Auto-Switch-OverScan >> Hardware for Atari ST-Computer) > > This depends on the board and is best asked of the manufacturer. One simple > thing that could rule out an easy swap is if the existing DAC is soldered > to the board instead of socketed. > > The Compuserve software that takes advantage of this chip tends to rely on > the extra BIOS support which Tseng labs defined and which STB implemented even > before they started selling boards which included the chip. Thus you may need > a BIOS upgrade unless you are into programming the Tseng chip and Sierra chip > at the register level. Might be fun, for some. > > -- regards, Steve Pacenka, Cornell U. What I would like to know is, can you still run the board as a standard SVGA once you have replaced the DAC chip with the super version?? Any replies appreciated - especially comments from those who have tried the new system out. Daf. -- ------------------------------------------------------------------------------- Davyd Norris : "Strange people physicists... In my opinion Physics Dept. : those that aren't already dead are in some Monash University, : way very, very sick." - Douglas Adams, Vic, Australia. : "The Long Dark Tea-time Of The Soul" -------------------------------------------------------------------------------
georgep@vice.ICO.TEK.COM (George Pell) (06/08/91)
In article <1991Jun6.191849.5312@vax5.cit.cornell.edu> n65j@vax5.cit.cornell.edu writes:
+The Compuserve software that takes advantage of this chip tends to rely on
+the extra BIOS support which Tseng labs defined and which STB implemented even
+before they started selling boards which included the chip. Thus you may need
+a BIOS upgrade unless you are into programming the Tseng chip and Sierra chip
+at the register level. Might be fun, for some.
+
+-- regards, Steve Pacenka, Cornell U.
Be aware that the STB Ergo-Powergraph board which uses the Tseng ET4000 chip
set has some MAJOR bios bugs, and is undergoing revision by STB. BIOS
versions 1.1 and 1.2 will not allow you to read access pixels with a y
value greater than 512. Version 1.3 is about to be released after debug
(I have a beta version).
geokize@cup.portal.com (Brian L Kaisner) (06/12/91)
First of all, replacing the existing DAC on a VGA board with a Sierra DAC probably won't work. I don't remember if the pinouts of the Sierra part are the same a the DACs typically used on a SVGA board. I _do_ recall that the Sierra part has monitor detection circuitry built-in, whereas DACs a year or more old require external comparators. I do know the Sierra part looks just like a regular VGA DAC until it receives certain commands from the VGA controller (Tseng in the current discussion) that put it into Hi-Color mode. The VGA controller then feeds the data into the DAC in the appropriate format on the rising and falling edge of the clock going to the DAC (twice the normal rate). That's all I remember off the top of my head. The more I think about it, the chances of a "DAC swap" working are very small, unless your board has jumpers to select such a manuever. Contact the board vendor ... - Brian