Ati Mach64 hates Floppy Drives - a truly weird problem!

[houseisland]

Please note that this is also posted in the controllers forum. If you have any advice could you respond there, since that is where I have now had the first response. Thanks.


Hi. This is a truly weird problem.

The card:

MACH 64GX "Vesa Local Bus" card w. 2 Mb ram (soldered in)

Bios VLB MACH1164 113-27801-102


Controller Type: VLB AT188800GX Rev. 1


The system housing the card:

Asus 486SV2GX4 w. 256K L2 Cache, I486DX4 100, 48 Mb Ram.

Promise DC3040VL-2 VLB Multi IDE controller card - IRQ 14 - w. 2 HDDs - primary controller, 4 Mb cache, but disabled because of NT.

Gemlight UN-1078E ISA IDE Controller / I/O card - IDE IRQ 15 w. 1 CD Rom, secondary controller - UARTS disabled - LPT2 IRQ7 Base Line 278.

Boca I/O AT55 I/O card - UART 2 disabled - UART 1 Com 1 IRQ4 - LPT1 IRQ7 Base Line 378.

Kingston KNE20T 10BaseT NIC - IRQ3 I/O 300

SIC Resource, Super Sound Origin, 32W3D Sound Card, Opti 925/941 chipset w. Cirrus/Crystal CODEC - in DOS originally IRQ5, I/O 530, DMA 0/1 - now IRQ 10 - MPU401 IRQ 2/9 I/O 330 - IDE interface disabled - card not installed in NT.


Problem:

The card passes all the diagonistics tests in the package posted by Ati, and it behaves well in most DOS 6.22 and NT applications until they access a floppy drive whereupon the screen begins a slow, almost psychadelic, process of meltdown. The screen is immediately restored by launching any application which has its own video drivers. For example: DOS commands and DOS utilities (Norton Commander), which use generic dos drivers, cause the meltdown when accessing floppies; Word 6.0 DOS, which has its own VGA drivers, restores the screen and does not cause any meltdown when accessing floppies; and any NT application which accesses a floppy starts the meltdown, but this process is reversed by opening another NT window and maximizing it.

The card resides in the adjacent slot to a Promise DC4030VL-2 multi-IDE Cache / floppy controller. Is EMI a possibility? I have tried attaching the floppies to the secondary controller but they fail in boot.

The bios chip was a little loose on the Ati card, age and heat maybe, and I tried gently reseating it. This action, however, changed nothing, neither improving nor worsening the performance of the card.

Any idea?


[This message has been edited by houseisland (edited June 08, 1999).]