Love these EISA 486 boards with custom local bus slots! It's strange that being an OPTi-based board it doesn't feature the OPTi local bus (which looks just an EISA slot).

So, we can at least tell what it ISN'T:

• OPTi/Orchid local bus
• Gigabyte local bus (two 16-bit ISA slots)
• ECS local bus (same connector as VLB)
• C&T "Wingine" local bus (16-bit ISA slot followed by an 8-bit one)
• Joindata local bus (similar to VLB but with an additional set of connectors)

This thread is a good reference for custom local buses.

Also, what the hell is that slot crammed in between the two top EISA slots?

The black slot between the EISA slots at the top is for an additional (proprietary) RAM board.

Found something, there is an ad about that motherboard on Sep-1992 BYTE magazine:

https://archive.org/details/eu_BYTE-1992-09_O … e/n213/mode/2up

The local bus VGA card is called "A VIEW-2L" (there is also an "A VIEW-1L" mentioned below) and from the label on the BIOS chips it seems to be made by AIR themselves. Due to the low resolution of the picture, I cannot make out what graphics chip is used.

EDIT: it is mentioned under one of the small pictures that it's a "Local Bus S3 VGA Accelerator". An S3 911 perhaps?

TheMobRules wrote on 2024-03-11, 16:19:

OPTi/Orchid local bus

One thing I learned in the mean time: While the OPTi and the Orchid local bus both are based on the EISA connector, they are not the same, and can be visually distinguished. The OPTi local bus is mechanically identical to the EISA bus, whereas the Orchid local bus has a key in the slot preventing the insertion of 16-bit ISA, EISA or OPTi local bus cards into the slot.

See this post for reference: https://www.vgamuseum.info/index.php/cpu/item … -tseng-et4000ax (that's the thread in which I learned the the OPTi and the Orchid local bus are clearly different).

Thanks for digging this out!

TheMobRules wrote on 2024-03-11, 18:40:

..."Local Bus S3 VGA Accelerator". An S3 911 perhaps?

It seems to be quite a large chip, maybe S3 805?

The mainboard itself is quite well performing with a ST DX2-80 5V CPU.

I love all the AIR and ALR stuff, the build quality was excellent.
The 4 chips of the chipset are also labeled:
DBC - Data Bus Controller
MCC - Memory Cache Controller
EBC - EISA Bus Controller
ISP - Integrated System Peripheral

Did they mix 28-pin (narrow) and 32-pin (wide) cache chips? How did that happen?

TheMobRules wrote on 2024-03-11, 16:19:

Love these EISA 486 boards with custom local bus slots! It's strange that being an OPTi-based board it doesn't feature the OPTi […]
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Love these EISA 486 boards with custom local bus slots! It's strange that being an OPTi-based board it doesn't feature the OPTi local bus (which looks just an EISA slot).

So, we can at least tell what it ISN'T:

• OPTi/Orchid local bus
• Gigabyte local bus (two 16-bit ISA slots)
• ECS local bus (same connector as VLB)
• C&T "Wingine" local bus (16-bit ISA slot followed by an 8-bit one)
• Joindata local bus (similar to VLB but with an additional set of connectors)

This thread is a good reference for custom local buses.

Also, what the hell is that slot crammed in between the two top EISA slots?

Don't forget the Micronics Local Bus! I have the Micronics ASIC EISA, which has it, I posted some time ago about it 😁