First post, by Madao
Hello People.
Puplished first gerber file with CSV (few value is incorrect, i recommend : use seconds URL). this version is stable
Re: S3 Vision 968 VLB replica
Puplished second gerber file with CSV , drawing of brackets and ROM-dump.
Re: S3 Vision 968 VLB replica
Pleas look at first after S3 Chip, it is current not avaible , utsource haven't him.
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Here is a bomb from a newbie. (but i am long in this hobby (my main hobby is test equipiment gears -> wellenkino.de (german))
I keep my frist PC (based 486 DX2-66) from my childhood, but this PC hat only Trident ISA Card, which it is replaced fast by S3 Trio32 VLB. (but i search yet driver for him for Win 3.1 )
And i wish a VLB card with 4 MB VRAM. S3 964 & 968 VLB with possibility of 4 MB VRAM is damn expensiv !
I have think: I make now himself a VLB-Videocard with S3 968 Chip, since i did found datasheet of 86C964 (968 datasheet also, but no pinout , 964 and 968 is eletric same): https://datasheet4u.com/search.php?sWord=86C964
Reference is a german made video card : SPEA Mercury P64V, which SPEA didn't make VLB-variant of him.
Working on pcb design take three week (thanks corona , i have much more time)
First picture of selfmade 968VL-card.
First life
But it is instable, massive pixel fail after short run time. Card run at this time only in textmode/VGA , not more test.
Find of cause of fail is fast: clock-line is very long (over 20cm ) and i put resistor as terminator -> run stable in textmode.
Next step: Check of high resolution -> freeze.
Cause-find is also fast, because i did make a notice: i have swapped inner layer of PCB by my mistake with kiCad (PCB Layout). (1-3-2-4 Layer )
Result: clock-line is not shield by mass-area from DAC-control & data line at top edge from card. I replace memory clock line with coax-cable -> no freeze anymore and stable runs.
Next problem: non stable picture, if windows use hardware-cursor.
Line flicker, while hardware cursor change from arrow to hourglass and back.
Reason is also mistake with inner layer of PCB, replace video clock line with coax cable.
The story countines with next posting, picture attach limit.