Hardware errata

This is a list of known hardware errata in Nvidia graphics cards

NV3

Early VBIOS bugs

While not technically a hardware errata, most likely due to an unknown issue with the video BIOS code in certain very early NVidia RIVA 128 units, certain VGA functions are broken. This causes garbage characters to appear inside of the Windows 98 Startup menu while trying to boot from CD-ROM.

This bug is known to exist in very early STB Velocity 128 units with VBIOS version 1.60, dated 8 August 1997, with GPUs manufactured in July 1997; this behaviour was discovered on a chip manufactured in week 33 of 1997, VRAM manufactured week 25, a 1.60 Velocity 128 VBIOS with a label on top reading 9/17/97 and a final board manufacture date of 10 October 1997. This behaviour does not appear to exist on all other VBIOSes, which are dated 3 September 1997 or later. There is no workaround for this bug other than potentially updating the VBIOS, although using a method that involves mashing the down arrow key you can still get into Windows 98 Setup with no problems.

It is unclear if this issue originates from Nvidia, or any modifications STB Systems may have made to the VBIOS code.

Extremely strange behaviour on turning off interrupts

On a NV3T (RIVA 128 ZX) card, turning off interrupts did not turn off interrupts, but instead caused all areas of MMIO not to be mapped to a register to endlessly decrement, wrapping over to 0xFF when they reached zero. The card showed no outward symptoms of this extremely strange behaviour.

CRTC scanline counter needs to be read twice

Under some circumstances, the CRTC scanline counter needs to be read twice to get a correct result.