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PALM VL-BUS (KG8PALMVL)

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First post, by noizex

Posted on 
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Hello everyone,
I recently bought this VLB card that's both I/O controller and a graphics card based on Cirrus GD5426. The name on the board says "PALM VL-BUS rev. 8.3" and there is also code KG8PALMVL but I was not able to find much about this card. In general it's rather straightforward, it has IDE/FLOPPY connectors, VGA Feature Connector, 2xCOM, 1xGame, VGA and LPT connectors. I thought having all this on a single VLB is interesting as I wasn't even aware such existed, so I got it to try it in my 486Dx2-66 build that I currently have in progress.

What bothers me though is the jumpers - as there is a lot of them and I could not find any manual for this board. Is the jumper setup on such boards for IO and VGA somewhat standardized so I could derive it from other manuals, or was totally random and will have to go jumper by jumper and try to figure out where it leads on the circuit board to have some vague idea what it does? Would be great to be able to ensure the jumpers are set correctly, knowing this is VLB card and there may be some more tweaking involved. Maybe someone has some scans of this manual or similar? Only mention of such board jumper layout I found was in some German forum (https://forum.classic-computing.de/forum/inde … ga-kombi-karte/) but it doesn't cover everything and is also a bit of a guesswork.

Here is the photo of the board (happy to upload more closeup ones if needed):

IMG_3442.jpg
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Appreciate any help in identifying this board and it's jumpers. Thanks!

Reply 1 of 1, by dionb

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VGA+I/O combo's are uncommon, but certainly not unprecedented. I have ISA and VLB cards with UMC VGA and I/O combos. They are particularly useful in small form-factor systems with very limited expansion (I use the ISA card in a 486DLC system with 2 ISA slots and basically nothing onboard, which frees up the other slot for LAN or sound).

KG8 is FCC manufacturer ID for Pacific Technology, but all I find using that is the FCC deposition for this very card, but without other documentation, and the forum link you already found.

Sadly, jumper layouts are not standardized - but based on location it's usually possible to deduce function. Tbh, everything you commonly need has already been found by jewesta. Looking at what's left:

JP13 2-3 IDE connector pin 38
JP14 2-3 IDE connector pin 37
JP15 2-3 IDE connector pin 36
JP16 1-2 (fix) IDE connector pin 33
JP17 2-3 (fix) IDE connector pin 35

These are all address/register pins on the IDE interface. Problem here is that the Appian ADI/2 controller is notoriously undocumented. Looking at another datasheet, these might be dual-purposed to set IDE cycle times (2 bits), VL-bus frequency (2 bits) etc. Problem is that these would be pretty hard to figure out by trial and error.

JP19 closed Cirrus Logic pin 52 IRQ2 connected IRQ2 disconnected

This is assign IRQ 2 to VGA enable/disable (not enable/disable VGA as a whole). Pretty standard VGA option.

JP20 1-2 Appian ADI2 IDE-Controller pin 24

Good question. I'd mess around and try to find out (or just ignore if all is working well)

JP21 2-3 GoldStar Prime 2 (LPT IRQ?) IRQ7 IRQ5

Definitely parallel port IRQ if in ECP mode.

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