It defaults at 1024x768 to 8514/A compatible timings (43 Hz interlaced). However you can load vmode to override to 60 Hz non-interlaced. It works here with 386 on Win95 and is most likely to work for WfW 3.11 too.
For convenience I have it here: ftp://78.46.141.148/driver/TSENG/ET4000/
The option you look for is probably VMODE 65M

I always thought that the ET4000/w32i could not do deinterlaced mode at 1024x768...wasn't that one of the main features of the ET4000/W32P (along with PCI support)?

Thanks elianda. I will see if Vmode works. Are the drivers in that directory for the Micro-Labs ET4000/w32i card? Micro-Labs has inconveniently removed their Win3.11 drivers from their website. http://microlabs.com/tseng.html

I think there are not specifically drivers for the microlabs card there, but one of the other W32 drivers should work.
like ftp://78.46.141.148/driver/TSENG/ET4000W32/win31/

elianda, have you personally confirmed that VMODE lets you run non-interlaced 1024x768 resolution on your TSENG ET4000 series ISA cards?

Yes, you can see this e.g. in this video https://www.youtube.com/watch?v=jeZIOZVLY0Q
The card is an ET4000AX with 1 MB.

Elianda, what colour depth at 1024x768 on your ET4000AX card?

I use 256 colors which is the max. I can get with 1 MB at this resolution.

Do you have a 2 MB card you can try for 32K or 64K colours at 1024x768?

I have 2MB cards, the run the 1024 res @ 16-Bit (64K colours)m or 800 res @ 24-Bit True Color. This applies to a Hercules Dynamite ISA as well as to a generic Tseng licensed card with a very similar layout.

FGB, do your cards run interlaced mode at 1024x768+ in Windows 3.1? I had to use VMODE 65M to get the Win3.1 driver working at 1024x768x256c.

Integral Tech I4596 PCI with ET4000/W32P..??

Check obobskivich post with link to pdf manual to my et4000/w32i card. It may provide some insight?

@FGB:

What is the user experience using 1024x768 in 16-bit colors with ISA Tseng/w32i cards? How does it compare to ATI Mach32 2MB EDO or CL-5429/5434 2MB also on ISA?

Well from my personal point of view, the speed is great, the picture quality is OK. The Cirrus card I have tends to be more blurry, maybe due to the integrated RAMDAC. The Tseng seems to be on par with my S3 805 card with 2MB but not as crisp as my Mach32 with 2MB of VRAM. The Mach32 also has the highest clocked RAMDAC @135MHz while the Tsengs W32i variations with 2MB usually have 110MHz on their ISA cards, the S3 805 also has a 110 or even a 80MHz DAC (don't remeber right now).
But the botton line is that I use these ISA-powered systems mainly do play DOS games, so Windows @Highres isn't much of a concern for me.

My card from Micro-Labs only has an 80 MHz AT&T RAMDAC. Even with 2 MB of RAM, it won't support 1024x768 at 32/64K colours. According to the manufacturer's website, the 2MB only adds memory interleaving (for Windows?) and 1280x1024 interlaced mode only. Does the model with a 100 MHz+ RAMDAC support 1024x768 at 32/64K?

To calculate the minimum required pixel clock you can use the General Timing Formula calculation sheet from VESA as helper http://www.cs.unc.edu/Research/ootf/FAQs/Video/GTF_V1R1.xls
(just if you don't want to calc yourself)

However in reality to have the higher modes actually available the RAMDAC has to be higher clocked as it also depends on how it fetches the data from RAM, Waitstates etc.
As a rule of thumb this means that on high color modes the theoretical maximum refresh from pixel clock calculations has to be reduced in reality due to memory bandwidth constraints.

TIGA cards with a 135 MHz DAC usually limit at 1280x1024x64K at 60 Hz (this was 1992)
with a 170 MHz DAC you get 1600x1200 at 60 Hz (there are also a few ISA cards with 170 MHz DAC like the SPEA Mercury Pro)
with 220 MHz DAC you get 1600x1200 at 77 Hz (e.g. Cornerstone ImageAccel PC161i also from 1992)

more current cards may push further to the pixel clock limit.

I have seen 8-bit and 16-bit RAMDACs. What is the difference if they both operate at the same speed?

Also, I believe the MicroLabs card DOES support 1024x768 at 64k colours, but only in interlaced mode.

Anonymous Coward wrote:

I have seen 8-bit and 16-bit RAMDACs. What is the difference if they both operate at the same speed?

Also, I believe the MicroLabs card DOES support 1024x768 at 64k colours, but only in interlaced mode.

The difference is the color depth: 8-Bit means the DAC is capable of 256 colours, 15-Bit 32768, 16-Bit 65536 and 24-Bit 16 Million colours.

I don't know if that is entirely correct. If you look at the datasheet for the ICS5301 RAMDAC it is described as being an 8-bit DAC that supports true colour modes:

http://www.datasheetarchive.com/dl/Scans-060/ … A2IH0067336.pdf

Here is ICS5341, described as a 16-bit DAC. It also supports true colours.

http://www.datasheetarchive.com/dl/Scans-060/ … A2IH0067338.pdf

Here is TLC34075. Although not specifically stated it is a 32-bit DAC. It is found on high end cards.

http://www.datasheetarchive.com/dlmain/Datash … /DSA-705801.pdf

RAMDAC bus width seems to refer to the number of datalines, not necessarily how many colours can be rendered.

According to the documents each of the ICS chips actually contain three DACs. I believe there are separate ones for red, green and blue. I would guess that if you are rendering 24-bit graphics, it would require 3 accesses to the 8-bit DAC but just 2 when using the 16-bit DAC. Most likely this would make 8-bit RAMDACs a poor choice for using 24-bit colour modes (even though technically they can do it). I didn't really look into it carefully. Anyone know for certain what's going on?

When I purchase cards, I always go for the ones that have RAMDACs with a high pin count.