MikeSG wrote on 2025-04-30, 17:01:

DEAT wrote on 2025-04-30, 01:43:

There is almost no difference between a Trident 8900D and a GD5434/ET4000 W32i when it comes to WinG/DirectDraw performance at the same ISA speed [...]

By DirectDraw games I mean Starcraft & Diablo that use BitBLT in the actual game. On a CL-GD5429 those games are both a 5FPS slideshow. On a Chips 65545 & S3 928 they run borderline playable but not quite. This is at 640 x 480 x 8bit.

About video memory clock vs ISA bus clock.

Just tested overclocking the memory in a CL-GD5429 from 50Mhz to 80Mhz, 16Mhz ISA clock.

Starcraft: ~7FPS before. ~10FPS after. 10FPS is a screen full of busy units, roughly the same as the Chips 65545 and S3 928 did with 32-bit memory.

WinTach:
At 640 x 480 x 8-bit most of the performance stopped improving at 60Mhz, except Excel which was linear with memory clock.
At 640 x 480 x 16-bit, Excel scored a +34% improvement, which was more than the S3 928 did with VRAM.

It looks like with the 64-bit/interleaved 32-bit cards (1.5 - 2x faster at Starcraft) being memory-mapped over a larger video ram width, that data can be moved in larger chunks, therefore more is available to the chip. Higher memory clock is more for high colour/high-res applications.

How often drivers can pack what's needed into video ram is the other metric.

Hi,
did someone here build Graphics Gremlin? I made PCBs some years ago but now finally programmed the bitstream to SPI flashrom (verify OK) and try it out. But unfortunatelly I have some memory problem, some parts of screen looks garbage. Both in CGA (TXT/GFX) and MDA modes. I tried 2 different 386 MBs, also tried lower ISA freq. as possible, didn't help. I had ordered the SRAM IS61WV5128BLL-10KLI and FPGA on Mouser so they should be OK. I measured with DMM there are no shorts/no connections on address lines around A10.
BTW is there newer bitsream/functions than from Github (isavideo.binm, 405460B, MD5: e6128013f166cefd444c4d7071461bbf)? Is there some contact to TubeTime?
Here's how the screen looks in POST, MM and GFX mode 04 looks:

I will check the soldering under a magnifier but I couldn't see anything obvious on my soldering work.
http://rayer.g6.cz/1tmp/Graphics_Gremlin.jpg
Please can someone confirm that the current bitstream on Github is working?
https://github.com/schlae/graphics-gremlin/bl … g/isavideo.binm

RayeR wrote on 2026-01-25, 17:15:

I will check the soldering under a magnifier but I couldn't see anything obvious on my soldering work.
http://rayer.g6.cz/1tmp/Graphics_Gremlin.jpg

Hi,
Maybe it's the way the light is hitting the board but these all look a bit weird to me.

I looked at it under magnifier but didn't find anything obvious, just maybe suspicious...
So I rather fluxed FPGA pins and resolder it again carefully under magnifier.
Yeah, it wroks now!
But I found it has problem with faster ISA bus. My test setup is 386/486DLC with boosted ISA to 10MHz (CLK/4). In this case POST screen looks fine but at the end there starts appear random chars on the screen. I had to go to setup and increase divider to CLK/8 - 5MHz and then it was finally without artifacts and memory test passed. Also interesting that async option 7,15MHz works too while CLK/6 - 6,66MHz had issues. Do you have similar experience?
Also I tried dualhead setup VGA+MDA in TurboDebugger - it's a nice feature 😀
That's a pitty that nobody seems extended FW features for years...

RayeR wrote on 2026-01-27, 06:51:

But I found it has problem with faster ISA bus. My test setup is 386/486DLC with boosted ISA to 10MHz (CLK/4). In this case POST screen looks fine but at the end there starts appear random chars on the screen. I had to go to setup and increase divider to CLK/8 - 5MHz and then it was finally without artifacts and memory test passed.

If your XTAL on the motherboard is 80MHz, CLK/4 may be 20MHz, and CLK/8 is 10MHz. (?)

The ZWS (Zero Wait State) jumper on the ISA bus typically works up to 12.5MHz also. Not sure if your card uses that.

Damn, yes there's 80MHz XO and you are right!
Just checked with f-counter on ISA bus CLK pin. System boots ISA at 8MHz and then switched to 20MHz after POST finished.
Divider options are: /2, 3, 4, 5, 6, 8, 10 and async 7,15MHz.
So I run my system insanely overclocked all the time without noticing it. I just got some bonus FPS in Doom with fast S3 Vision 928, neither IDE controller, ethernet card, AWE64, USB-ISA with CH375, POST card complained, just the Gremlin...