I have these two VESA Local Bus Graphics cards.
Both are in working order but, I would like to know what settings the jumpers on each card represents.
The S3805 card has three jumpers on the left hand side (if viewed from the top, with the bracket on the right hand side) whereas, the Cirrus Logic has one jumper more or less in the middle of the card.
My guess for the GD 5428 is: allow IRQ 2/9 usage ON - OFF
General hints:
you find these jumpers on VESA VGA cards: IRQ 2/9 enable, memory size, write wait state 0/1, FSB <=33 Mhz / FSB over 33 Mhz
plus some, especially earlier models allow for RAMDAC related settings like refresh rates for 800 x 600 and 1024 x768 (interlaced / progressive scan), BIOS memory location etc.
By observing the jumper location and the connection lead to nearby chips, you can make an educated guess about the function 😀
+ there is always trial and error: you test and benchmark the card for feature and speed changes after re-jumpering.
"Ita in vita ut in lusu alae pessima iactura arte corrigenda est."
Thank you for the advice.
I actually tested both cards on the old Landmark Speed test (v2.0 & v6.0).
The S3 has a video speed rating of 16661 chr/ms whereas, the Cirrus Logic only managed 8777 chr/ms.
For matter of interest, my old Tseng ET4000AX (16-bit ISA) card managed about 3000 chr/ms.
On the Cirrus Logic, with the jumper on or off, it made no difference to the speed.
I haven't played around too much with the jumper settings on the S3 as it is working fine.
Just wondered what it was for.
The cards have vacant chip slots. Maybe VRAM expansion?
I guess it is possible the jumpers configure that
Yes, you're right.
On the S3 card, I traced both jumper JP4 & JP5's connection leads to the vacant memory slots.
Fortunately, I have no need to expand the memory on this card since I'm using it in my old 486 PC. The current 1mb of on board memory is sufficient for playing my DOS games.
