VOGONS


486DX-50 MHz EISA system

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Reply 40 of 57, by mpe

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weedeewee wrote on 2021-04-23, 12:05:

EISA has a 32 bit data bus so would be four times as fast as an equivalently clocked 8 bit ISA bus or twice as fast an equivalently clocked 16 bit isa bus.
and it has a 32 bit address bus.

Yes, in theory. The bus might be twice as fast if using 32bit writes to video RAM which is not common in DOS and not even in Windows 3.1.

EISA graphic card market pretty much concluded in 1992 or so, whereas ISA cards continued to be produced for a couple of extra years so you can get slightly better cards for ISA.

Even the ELSA Winner 1000 that has both EISA and ISA connector showed a hair better performance in ISA mode for some reason.

EISA was made for SCSI, network cards and such. The main benefit was CPU-freeing bus-master capabilities and arbitration and not the bandwith.

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Reply 41 of 57, by evasive

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So a Genoa board sold under the FreeTech brand since the POST screen mentions the "10X".,or the other way around as the markings absolutely say: FreeTech board (ASY xxx-00ABC-xx is FreeTech/Flexus by definition). This BTW means the model name is 486F10X, so thank you for that info, still we would like to have a bios dump 😁 One reason for that is to find the actual core version of the bios, as the POST ID seems to be mutilated a bit. Where that 1017 is, the should be 101094-<chipset info>-8/0/K something I think. The only way to dig that up is from the bios dump itself.

Reply 42 of 57, by simon_e_hall

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evasive wrote on 2021-04-24, 10:55:

So a Genoa board sold under the FreeTech brand since the POST screen mentions the "10X".,or the other way around as the markings absolutely say: FreeTech board (ASY xxx-00ABC-xx is FreeTech/Flexus by definition). This BTW means the model name is 486F10X, so thank you for that info, still we would like to have a bios dump 😁 One reason for that is to find the actual core version of the bios, as the POST ID seems to be mutilated a bit. Where that 1017 is, the should be 101094-<chipset info>-8/0/K something I think. The only way to dig that up is from the bios dump itself.

Was playing around with the machine today, seeing if there was any ways I could tweak the BIOS (Wait states, timings, etc) or put a different BIOS on the board.

I have attached a zip file with a few different saves of the BIOS using NSSI and AMI BCP, also a couple of screen shots for further information. I would be interested to see someone else's analysis of this BIOS, this board is a bit of a mystery, only found one press cutting for it online, which again states it is a Freetech board.

The lack of BIOS options is annoying, especially when compared with other BIOS options of the era, I was thinking of making my own BIOS image, but it has been a very long time since I did that. (i.e. do a hash of two similar BIOS images one with EISA compatibility and another with more flexibility).

So I tried a little experiment, I inserted a similar AMI 486 ISA BIOS (had a few lying around) in the machine to see what would happen, better then expected really:

1) The ISA BIOS only sees up to 32MB

2) Does not initialise the EISA cards, apart from the VGA which works from boot

Both results as expected, but it would successfully boot up to needing me to insert a boot disk, I was just seeing if playing with any wait states on a BIOS with more options would improve memory performance, but this all needs a little more experimentation, i.e. put a ISA IDE card in and see if that works and boots, etc. But now my baby son is awake, so no more playing with computers for me today.

Also I put 15ns cache chips in, as I said before from experience this usually achieves nothing apart from bragging rights but you never know, and sure enough, it achieved nothing, benchmark results remained the same.

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Reply 43 of 57, by weedeewee

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simon_e_hall wrote on 2021-04-26, 12:27:

So I tried a little experiment, I inserted a similar AMI 486 ISA BIOS (had a few lying around) in the machine to see what would happen, better then expected really:

If the original bios is an ami bios one, you could try a little experiment with an old Amisetup util which allowed to change hidden settings

Reply 44 of 57, by simon_e_hall

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weedeewee wrote on 2021-04-26, 13:59:
simon_e_hall wrote on 2021-04-26, 12:27:

So I tried a little experiment, I inserted a similar AMI 486 ISA BIOS (had a few lying around) in the machine to see what would happen, better then expected really:

If the original bios is an ami bios one, you could try a little experiment with an old Amisetup util which allowed to change hidden settings

Tried that to begin with, interesting to note how many options are hidden, strange things like turning the memory tick sound off, most of the deleted options are shadow locations, which I had a play with but again not much joy.

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Reply 45 of 57, by pvlst

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Hi mpe,
I recently obtained the same board. It has some minor differences but I guess it's more or less the same. Do you happen to have a better manual for the board than the stason's or win3x.org? There are jumpers marked W4, W5, W6, W20, W21, W22 and I'd like to know what are they for. I guess some of them might be for setting the cache size, others might be for configuring the CPU.

My mobo was apparently using a plain 486DX 33MHz CPU (I put in the SX version just to check whether it works), I'm trying to upgrade. But I don't want to damage the CPU.

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Reply 46 of 57, by simon_e_hall

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pvlst wrote on 2021-05-17, 18:36:

Hi mpe,
I recently obtained the same board. It has some minor differences but I guess it's more or less the same. Do you happen to have a better manual for the board than the stason's or win3x.org? There are jumpers marked W4, W5, W6, W20, W21, W22 and I'd like to know what are they for. I guess some of them might be for setting the cache size, others might be for configuring the CPU.

My mobo was apparently using a plain 486DX 33MHz CPU (I put in the SX version just to check whether it works), I'm trying to upgrade. But I don't want to damage the CPU.

You appear to have a 33 MHz crystal on yours, did it work? When I changed mine (including correct CPU) it refused to boot, only liking a 50 MHz crystal, which is why my AM5X86 is set to triple clock, it for some reason didn't want to work at 200 MHz! 😀

Reply 47 of 57, by simon_e_hall

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Also mine has had a little tidy up, felt embarrassed with the state of her in the first photograph, I have also had a few parts changed.

1) SB16 is no longer SCSI version but swapped from my Voodoo II build, and is now a SB16 with bug free DSP and ASP chip.

2) SIIG I/O Card is now PT-606e multi I/O card, because I have removed the tape drive and replaced it with a CF Card adapter and adapter, to allow easier data transfers between my main PC and this one.

3) Also dropped from four SCSI drives to two, both with a larger capacity again RCA to 50 pin adapters, still cannot get the RAID to work, DPT card just refuses to build it, I can only assess it does not like the fancy drives.

Going to experiment with the graphics cards next, once I have put the operating system back on her, have a Diamond SpeedStar 64 which has served me well, but it seems wrong to replace it in an EISA build, I do have a Compaq EISA card somewhere, so when I have some time to myself might see how all three compare.

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Reply 50 of 57, by garyglitta

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swaaye wrote on 2021-07-26, 20:00:

FYI, VOGONS is not a marketplace.

Sorry bout that, just these things are exceptionally hard to find and thought maybe someone might want it. Feel free to delete my post, was not my intention to break rules.

Reply 51 of 57, by simon_e_hall

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Well, I think my board is beginning to die, getting the message 'EISA CMOS INOPERATIONAL' on boot, definently not the battery as that is new, and re loading the EISA information does not refresh it, also before this message, I was beginning to having other issues, i.e. network card being recongnised but not passing traffic, but works after several reboots, etc.

Bit sad really, had many a good 486 gaming session on this machine and this has been a joy to play with upgrading and tinkering with.

Well, think it is time to start looking for a successor.

Reply 52 of 57, by PC-Engineer

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Sounds like insufficiency of EISA NV RAM and/or the correspondig battery. Did you changed the Dallas 1225 too? Also check the Voltage of your Battery, this should be over 3.2V.

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Reply 53 of 57, by simon_e_hall

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PC-Engineer wrote on 2021-10-19, 12:58:

Sounds like insufficiency of EISA NV RAM and/or the correspondig battery. Did you changed the Dallas 1225 too? Also check the Voltage of your Battery, this should be over 3.2V.

Thanks for the information, unfortantly, yes I have changed both, and voltages checked, changed the battery anyway for new ones, checked those as well. In fact this was the first thing I thought it would be, even looked up the error message in an old BIOS Bible document, which points to this error message being a battery issue.

Reply 54 of 57, by rmay635703

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Anyone besides me overclocked a dx50 motherboard to 60mhz FSB using a different clock crystal?

I never benchmarked but am curious if it gives a performance boost or is actually slower (my dx50 was ISA, boo, and ran OK at 60mhz but that was early in my Pc days)

Reply 55 of 57, by Disruptor

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rmay635703 wrote on 2021-10-19, 14:34:

Anyone besides me overclocked a dx50 motherboard to 60mhz FSB using a different clock crystal?

I never benchmarked but am curious if it gives a performance boost or is actually slower (my dx50 was ISA, boo, and ran OK at 60mhz but that was early in my Pc days)

An AMD 486 DX4 120 should do this with 2x multi (considering correct voltage).

Reply 56 of 57, by simon_e_hall

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rmay635703 wrote on 2021-10-19, 14:34:

Anyone besides me overclocked a dx50 motherboard to 60mhz FSB using a different clock crystal?

I never benchmarked but am curious if it gives a performance boost or is actually slower (my dx50 was ISA, boo, and ran OK at 60mhz but that was early in my Pc days)

Not this callsign, I usually tweaked the CLK/ setting in the BIOS, recall overclocking my Zenith 386 by swapping the crystal out, but not a 486.

Reply 57 of 57, by Anonymous Coward

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rmay635703 wrote on 2021-10-19, 14:34:

Anyone besides me overclocked a dx50 motherboard to 60mhz FSB using a different clock crystal?

I never benchmarked but am curious if it gives a performance boost or is actually slower (my dx50 was ISA, boo, and ran OK at 60mhz but that was early in my Pc days)

Yes. I have been able to clock my SuperEISA board to 60MHz. I ran Cyrix 5x86-120 at 2x60.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium