Cyberdyne wrote on 2021-08-04, 08:11:
Tseng Labs cards have got some unusual cult following. Really they only shine at pure ISA troughtput.
If you are after DOS gaming experience, ISA throughput is the only metric that matters. So it makes a lot of sense for DOS gamers to evaluate ISA graphics cards merely on the throughput. The cult over ET4000AX cards already started in the 90s, and at that time, the ET4000 cards were the fastest widely available and affordable ISA graphics cards.
Cyberdyne wrote on 2021-08-04, 08:11:
If you have a local bus or a PCI card, then a good S3 or Cirrus card is much better and more compatible. And even then a CL-GD29 ISA is almost as good as ET4000AX.
I compared a CL-GD5426 VLB and an ET4000AX ISA graphics card in the same DX33 system using write performance (in SVGA 256-color modes) as metric around 20 years ago. I don't remember whether I overclocked ISA to 11MHz, but the results were that in 640x480 @ 60Hz, the Cirrus card was noticably faster, but by far not making use of the full VL potential. I think it was around 30% speed increase. On the other hand, in 1024x768 @ 75 Hz (the highest mode the monitor I used supported), the better memory interface of the ET4000 card showed it potential and ISA transfer rates kept being good, whereas the Cirrus card dropped below the ET4000 card. The fair, but not stellar results of the Cirrus cards are easily explained by them being 16-bit chips. The CL-GD5430 is the first cirrus chips to feature a 32-bit bus interface the local bus. The same is true for the ET4000AX!. If you want to follow the Tseng cult onto the VL bus, don't get started below the ET4000/W32 which features a 32-bit data path. If there are ET4000AX VLB cards, they are not cult-worthy, although they might be a bit faster than the ET4000AX ISA cards due to the higher bus clock.
The discussion about 32-bit capable cards is only relevant for games that use 32-bit access to video memory. This is the case for most SVGA games (640x480, 256 colors) like WarCraft II, but often not the case is 16-color or games using the undocumented enhanced 256-color mode called "mode X". Mode X is a clever hack that switches the original 8-bit VGA hardware into a mode that allows utilizing the whole 256KB of video memory instead of just 64K as in the standard VGA 256-color mode. This hack does not hamper the memory performance of 8-bit VGA cards, but it makes mapping 32-bit CPU accesses to video memory access a lot more difficult, and it has a memory model that discourages 32-bit access by applications.