nuno14272 wrote on 2023-03-23, 14:15:two dallas chips ? and two fpu's ?
Exactly what rasz_pl said. A lot of EISA boards have “less-conventional” Dallas setups, since they need some sort of battery-backed NVRAM to store EISA configuration information. Most use a 1387/1488/something of that sort, but this uses a separate NVRAM module and more conventional DS1287 for RTC features only. P-EISA boards like those with the HiNT Caesar chipset do not use Dallas NVRAM modules, however. They have starkly different NVRAM setups.
The Weitek is indeed memory-mapped, and it’s sort of a strange one. They were sold for a short time as specialized floating point units, and their performance was supposedly eclipsed by the DX2-66’s time. I say supposedly, because the quick test I ran showed otherwise; that being said, there’s probably still merit in the statement that most end users were better off not paying large sums for a 4167 when the internal co-processor in their 486DX2-66 was more than adequate.
Ozzuneoj wrote on 2023-03-23, 14:37:I think that is one of the most densely populated boards I have ever seen (that wasn't just a memory board). […]
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WJG6260 wrote on 2023-03-23, 00:51:Picked up this neat AIR 486SE board. Lots of discrete PALs/GALs/logic on this one. Seems to have a Dolch-branded Phoenix BIOS. I […]
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Picked up this neat AIR 486SE board. Lots of discrete PALs/GALs/logic on this one. Seems to have a Dolch-branded Phoenix BIOS. It needs a new Dallas RTC and I’d bet money the NVRAM’s battery is shot. It runs a fixed 33MHz FSB, probably derived via the 66.67 MHz oscillator.
I’ve been curious about the Intel EISA chipset. Apparently, this initial revision was somewhat buggy. Performance is acceptable, but the board lacks L2. If only there were cache interposers.
Also, picked up this Weitek 4167. Figured this was the perfect board with which to give it a spin. It was slightly faster than the DX2-66’s FPU in the Weitek demos. Neat.
EDIT: It also has EISA CFG-controlled onboard parallel/serial. That’s pretty interesting.
F5553759-E653-424E-8B0C-318BF0530DDC.jpeg
I think that is one of the most densely populated boards I have ever seen (that wasn't just a memory board).
What exactly does this board do that would require so many additional components?
I don't know anything about how PCB design was done back then, but I sincerely hope all that stuff didn't need to be traced manually. 🤣
Yeah, it’s a mess 🤣
Intel’s EISA chipset is always on boards like this. rasz_pl’s point—that Intel sucked at custom chips—is seemingly accurate, as every single Intel-based EISA board looks like this. I believe there’s only two that are in Baby-AT form factor: this one, and the A.I.R. 486ES. While this board is marked as such, it is 100% a 486SE. The 486ES has 8 EISA slots. I think integration may have improved with the 350DT chipset, which was supposedly the bug-fixed revision. The build quality of this board is tank-like, but the design and layout are absolutely atrocious.
rasz_pl wrote on 2023-03-23, 14:51:dallas is not only RTC but also battery backed SRAM, EISA requires more memory to store config
weitek is not a normal FPU, its m […]
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nuno14272 wrote on 2023-03-23, 14:15:
two dallas chips ? and two fpu's ?
dallas is not only RTC but also battery backed SRAM, EISA requires more memory to store config
weitek is not a normal FPU, its memory mapped https://www.geekdot.com/weitek-abacus-fpu/
Ozzuneoj wrote on 2023-03-23, 14:37:
I think that is one of the most densely populated boards I have ever seen (that wasn't just a memory board).
What exactly does this board do that would require so many additional components?
Intel really sucked at custom chips and integration before Pentium era. I count ?23? PALs 😮
The PALs are everywhere on this thing! No wonder it lacks L2—there’s just no room! 🤣
I wonder if Intel EISA chipsets did not sell well because of the sheer cost of implementation. Swaths of discrete logic are everywhere on their early boards, like you noted, and that could not have been beneficial for production costs.
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