feipoa wrote:

Well, the latest Biostar BIOS worked on my original version MB-8433UUD. Try running your board at 33 MHz and adjust the CMOS settings.

I'm pretty sure that chips marked as Cyrix 5x86-120/4x were originally meant to be Cyrix 5x86-133/4x chips, but they failed to qualify at 133 MHz. So the 120/4x chips were specifically tested and failed at 133 MHz. The Cyrix 5x86-120/3x chips would not have been tested at 133 MHz, so there is a greater chance of getting the 5x86-120/3x chips to run at 133/2x.

Cyrix 5x86-133/4x chips are a lot rarer Voodoo 5 boards, so I don't think anyone would make that trade.

From what I've seen, V5 boards are rarer in my neck of the woods. Every collector that has one has imported it. I know a couple of guys in romania who own 133Mhz cyrix chips - odd ones too - one just says "Cyrix" on it - maybe an engeneering sample? An the other guy has the regular labeled version. In fact I believe he has two of them. There's also a couple of guys in russia that have some of these - saw the posts on CPU world - but none of them will sell/trade.

I'm hoping I'll come across someone with more interest in 3dfx parts then in 486 gear, witch is not uncommon. Frankly I know way more collectors interested in video cards in general rather then 486 stuff. For them a V5 5500 is of greater value then a fast 586.

BitWrangler wrote:

I had an Amptron/Elpina UMC chipset board and a 5x86-100... Now after a few months of owning it, sometime in 96, I stumbled across the higher clock settings and ran it at 2x60, I also found 66Mhz, I think, thing was, it didn't actually seem quite as fast at theoretical 133 as 120, benchmarked slightly lower, I guess it was extra wait states or something starting to kick out recoverable errors. Apart from that it did seem to run okay if you kept it cool. I had a clip on fan jammed on bonded on heatsink.

(Thanks very much for documenting the high clock speeds on here, just about everyone I ever tried to tell about them called me a n00b, liar or crazy.)

Feipoa did it first. He has a few threads here on vogons dedicated to these chips and fast 486's in general.

Imperious wrote:

What an incredible coincidence, as I have been doing exactly that. You need to set the Keyboard controller to Award in Modbin ot […]
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kanecvr wrote:

How did the LS486e BIOS workout on the 4DPS? You might need to modify the LS486e BIOS using modbin to allow for the PS/2 mouse. There is a checkbox you need to tick.

What an incredible coincidence, as I have been doing exactly that. You need to set the Keyboard controller to Award in Modbin otherwise it won't work.
Other than that You lose 40Gig hdd support and gain the Y2K bug.
That was with the LS486E-D bios.

I am playing around with other bioses so will update this when I have some success.

Do keep us posted please. Thanks for the tip about the KB controller. Personally I'm hoping the Lucky Star bios is better put together and will help with overall stability. Maybe even EDO support?

kanecvr wrote:

feipoa wrote:

Well, the latest Biostar BIOS worked on my original version MB-8433UUD. Try running your board at 33 MHz and adjust the CMOS settings.

I'm pretty sure that chips marked as Cyrix 5x86-120/4x were originally meant to be Cyrix 5x86-133/4x chips, but they failed to qualify at 133 MHz. So the 120/4x chips were specifically tested and failed at 133 MHz. The Cyrix 5x86-120/3x chips would not have been tested at 133 MHz, so there is a greater chance of getting the 5x86-120/3x chips to run at 133/2x.

Cyrix 5x86-133/4x chips are a lot rarer Voodoo 5 boards, so I don't think anyone would make that trade.

From what I've seen, V5 boards are rarer in my neck of the woods. Every collector that has one has imported it. I know a couple of guys in romania who own 133Mhz cyrix chips - odd ones too - one just says "Cyrix" on it - maybe an engeneering sample? An the other guy has the regular labeled version. In fact I believe he has two of them. There's also a couple of guys in russia that have some of these - saw the posts on CPU world - but none of them will sell/trade.

I'm hoping I'll come across someone with more interest in 3dfx parts then in 486 gear, witch is not uncommon. Frankly I know way more collectors interested in video cards in general rather then 486 stuff. For them a V5 5500 is of greater value then a fast 586.

I have been in touch with nearly everyone who owns a Cyrix 5x86-133/4x - nobody will trade or sell for any price. There was such a chip on eBay a year or so ago with a very high reserve. I think the bids went up to around $400 or $500, but it never sold. For a high dollar value, you can still obtain a Voodoo5, not so much for the Cyrix though.

BitWrangler wrote:

kanecvr wrote:

feipoa wrote:

It is unlikely that a Cyrix 5x86-120/4x will work stable at 133 MHz. Mine does not.

My 5x86-120GP/2X works fine at 66x2, even with fast FP on @ 3.7 volts - BUT - the mainboard I used it in died. It was a Pine PT-430A from a PoS machine. I guess running it at 66MHz killed it - either that or something else. Now my MB-8433 is acting up with the latest bios, and with the stock bios it's stable but way to slow, and the 120 is not stable at 2x66 on it, regardless of voltage or bios settings. I've invested way to much time in this board, so I'm giving up on it for now.

A 4X chip would be a lot easier to run in most boards, but I can't seem to be able to get a hold of one. Meh - I'll probably come across one at one point - even if I have to trade my voodoo 5 for it.

I had an Amptron/Elpina UMC chipset board and a 5x86-100... Now after a few months of owning it, sometime in 96, I stumbled across the higher clock settings and ran it at 2x60, I also found 66Mhz, I think, thing was, it didn't actually seem quite as fast at theoretical 133 as 120, benchmarked slightly lower, I guess it was extra wait states or something starting to kick out recoverable errors. Apart from that it did seem to run okay if you kept it cool. I had a clip on fan jammed on bonded on heatsink.

(Thanks very much for documenting the high clock speeds on here, just about everyone I ever tried to tell about them called me a n00b, liar or crazy.)

My configuration of an IBM 5x86c at 133 MHz (2x66) is only barely faster than my Cyrix 5x86-133/4x. And you are correct, the issue is the wait states. At 66 MHz, you will be running cache with the slowest wait states and will need to add 1 or 2 ws for the RAM read time. You can see some results here, A brief comparison of Voodoo-Quake results on a 486

feipoa wrote:

I have been in touch with nearly everyone who owns a Cyrix 5x86-133/4x - nobody will trade or sell for any price. There was such a chip on eBay a year or so ago with a very high reserve. I think the bids went up to around $400 or $500, but it never sold. For a high dollar value, you can still obtain a Voodoo5, not so much for the Cyrix though.

Some local collector was interested in making a deal, but seems to be holding out for a little bit more right now. Last time I negociated a V5 5500 AGP + a Yamaha SW20-PC + a tualatin 1400 cpu for his 133MHz Cyrix - he seemed excited at first, but I haven't heard from him in a while due to my accident.

There's also a chance I might find a chip at rel computers - the company who originally sold my first PC. I've been emailing a guy who's worked there for a while, and apparently they have quite a few mid 90's machines and parts thrown away somewhere in a warehouse. Wish me luck 😀

kanecvr wrote:

Some local collector was interested in making a deal, but seems to be holding out for a little bit more right now. Last time I negociated a V5 5500 AGP + a Yamaha SW20-PC + a tualatin 1400 cpu for his 133MHz Cyrix - he seemed excited at first, but I haven't heard from him in a while due to my accident.

Sounds like he had time to think it over!

Based on my, quite limited, experience with 486 boards a fsb of 50mhz seems "gold" - although this may strongly deviate from board to board.
The UMC board I got(by accident) runs with all settings max at 50mhz(60ns ram, 12ns+15ns srams). Tried it with 60 and it broke down performance wise... as Feiopa already said, wait states - the bane to any 486 enthusiast's existence.
On the other hand the SiS based board that I have seems to thrive on 60mhz bus speed(sporting a DX4@120)... but I may see how it fares with 50 and less wait states... there could be a "pleasant" surprise ahead.

feipoa wrote:

Sounds like he had time to think it over!

Turns out he traded the CPU for a V5 5500 PCI and some nvidia NV15 engineering sample board - to a friend of mine (backstabbing bastard he new I wanted that chip 😵 ).

That's pretty messed up. I wouldn't classify him as a 'friend'.

feipoa wrote:

That's pretty messed up. I wouldn't classify him as a 'friend'.

You're probably right. Let's see if he's willing to trade for it - then I'll know if he is or isn't a friend. There's a strong possibility he'll trade for my Amstrad PC1512 since he's been eyeing it for months.

Well, I see Amstrad PC1512 computers on eBay right now, so it seems like an unlikely trade.

feipoa wrote:

Well, I see Amstrad PC1512 computers on eBay right now, so it seems like an unlikely trade.

Yeah, but not like my machine. Mint condition, 20MB hard drive + juko d16x 8 bit IDE controller and 1200MB Western Digital IDE drive + 720kb fdd drive (not the usual 360kb it comes with) - full 640kb of ram, original amstrad mouse and joystick, serial adapter that allows the use of regular MS serial mice, one Color and one B&W monitor (PC-CM and PC-MM), and a sound blaster 1.5 for good measure. I value the machine at about 500 euro. Not sure I want to let it go tough - as XT machines go, the 1512 is kind of hassle free when it comes to setting up and day to day use. The only annoying part is that the PSU is built into the monitor so you have to use the original displays.

I got the machine with a B&W monitor, 512kb of ram and the keyboard. No original HDD, it came with the Juko IDE controller and a (dead) 360mb connor 3.5" HDD witch was kludged into the case. Everything else I got from ebay except for the 20MB seagate drive witch I've been sitting on for a while. Getting it to work with the PC1512's MFM controller was a pain in the ass - took me about a week of research and fiddling to make the two work together.

As for ebay, it seems that even the basic model with no disk drive and a monocrome monitor goes for 150$.

The thing is, it depends how much value someone puts on these. For us 486 enthusiasts, a 133Mhz cyrix is priceless. For an XT enthusiast like my friend (who built his own XT from a kit he bought online) the 1512 is priceless. For a 3dfx collector... well, you get the point. Other things are of less value, held only for trading or completely useless, regardless of their value to other people.

Best of luck with the trade - I will be surprised if that trade goes through.

I've managed to get the latest modded bios for the Soyo 4SAW working with my 4DPS 2.11.

Pro's are as follows
1. CDROM can be selected as boot drive in bios (tested)
2. Some more performance options
3. Y2K compliant
4. Supports up to 120G HDD (tested)
5. Appears more stable.
6. ps2 tests ok

Cons
1. Must only be used with UV eraseable or OTP Eprom.
2. If EEPROM used, when ESCD update fails cannot boot again.
3. Bios lists 4 PCI slots but causes no problems.
4. Game port no longer available in Bios
5. Slightly lower memory performance but is stable
6. Have tried EDO memory but was not successful (EDO did not work with 4DPS anyway)

the lower memory performance I believe is just that The computer will not boot with unstable memory settings. I have only used with
60ns FPM and is way off my LS486 rev D performance with EDO installed.
The lower memory settings do not appear to affect DOS performance, at least with DX-2 66, haven't tried with my AMD 5x86-133
I'm happy to PM the bios if anyone is interested, but only to someone with a Eprom programmer. I will not make it publicly available due
to problems with Flashable eproms and bricking the board.

The 4DPS has a jumper that can set the bios chip type - flashable eeprom or uv erasable - did you try messing with that? It might be why the board fails to post with an eeprom.

JP4 BIOS Select:

1-2 FLASH ROM
2-3 EPROM

kanecvr wrote:

The 4DPS has a jumper that can set the bios chip type - flashable eeprom or uv erasable - did you try messing with that? It migh […]
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The 4DPS has a jumper that can set the bios chip type - flashable eeprom or uv erasable - did you try messing with that? It might be why the board fails to post with an eeprom.

JP4 BIOS Select:

1-2 FLASH ROM
2-3 EPROM

Thanks for that. It works ok with an EEPROM as long as the jumper is correctly configured then. If not it will
corrupt the Bios chip so I'd still prefer to only PM it to anyone.

I also tested the Lucky Star LS486 Rev D bios to see if EDO RAM works, it does not, so must be the revision of
the SIS chipset or some other hardware issue.

The next thing I'll try is loading this bios into my LS486 rev D and hopefully then that will work with larger than 8.4G hdd
and Y2K bios, but that's for later and another thread perhaps.

Here's some useful undocumented jumper settings for the ZIDA 4DPS:

JP18 is PCICLK:

1-2 = PCICLK : FSB 1:1/2 or 1:2/3 - not sure witch exactly, probably 1:1/2 like most other sis boards.
2-3 = PCICLK : FSB 1:1

JP17 is the CPU multiplier

2X = JP17 1-2, 4-5
3X = JP17 1-2
1X or N/A (floating) = JP 17 open
Unknown setting for cyrix chips = JP17 2-3 -

For 3.6v: for overclocking and some Cyrix chips (this jumper setting is taken from stason.org)

JP27 - open
JP28 - open
JP30 - closed (1-2)

Right, so I took a little time to test some BIOSes on my 4DPS and here's my findings:

1. Lucky Star LS486e bios works fine on the 4DPS.
2. There is absolutely no benefit from using the LS486e bios on the ZIDA - in fact, it's better to do the other way around. Using the ZIDA bios on the LS486e unlocks some settings, and enables PS/2 support for those courageous enough to try modding the motherboard for PS2. The Zida 4DPS bios is a tiny bit faster then the latest LS486e bios, and allows for HDDs up to 40 (or 120? cant remember) gb. The only issue is you will no longer have EDO dram support. The computer will post with EDO but freeze after updating ESCD (at least mine does). This can be easily fixed with modbin and award bios editor.
3. The 4DPS is a bit slower with the LS486e bios then it is with the 4DPS2014 custom bios.
4. No EDO support. The 4DPS is running an older revision of the SiS chipset witch does not support EDO.

I did come up with my own little modified version of the 4DPS bios - it's based on feipoa's 4DPS2014 rom:
- some unlocked options, especially in the PnP and Power management sections
- changed setup and bios defaults (removing the annoying bit where after a reset the bios disables the HDD controller by default)
- adds some changes to the way the turbo switch works - it now disables cache and adds PCI wait states to simulate a slow 386sx. Does not work with POD (P24T) and Cyrx 586 chips - it will only slow down the PCI bus and disable L2 cache. With other 486 CPUs it slows down the system significantly. On a DX4, clock speed is reduced to 33MHz, L1 and L2 caches are disabled and wait states are introduced to memory and PCI busses.

*there's a little cockup with the PnP Bios enable - it overrides "PCI slot A uses interrupt" in bios, but I considered the latter to be of more use. I'll fix it when I get a little bit more experinence working with modbin (a a bit more time).

DISCLAIMER !!!!! FLASH AT YOUR OWN RISK !!! I personally tested the bios with my Zida 4DPS Rev 2.11 and it works perfectly. I even tested it with a Lucky Star LS486e and it works fine on that board as well, but I cannot be held responsible if you brick your mainboard.

Download ZIDA 4DPS BIOS Version 500A 16/10/2017:

PNP Configuration setup doesn't do anything on these motherboards and with 4.51 Award bios.
I just had a look at this with Modbin, and there are a few selections trying to use the same screen real estate.
I would suggest turning off the IDE VESA options.

You are more game than I was playing with the turbo options. I had to redo modbin a few times before everything looked ok.

Too bad my 4dps is damaged. L2 cache doesn't work. POST screen reports the amount selected by jumpers, but cachecheck and speedsys report no L2 cache regardless of what bios, jumper combination or sram chips I put in it. Also there's what looks like an air bubble in the deeper layer of the PCB right near the cache sockets, and some of the deep traces there look damaged. I'll post a pic of it later... never seen anything like it.

kanecvr wrote:

It's a neat little board, with official 586 support, 3.3 / 3.6 and 5V voltages and FSB up to 66MHz (unofficial). Looking at my sample (PCB Ver 2.11)

Hi! I know it's an old thread and not exactly related to my question, however since I cannot find some crucial info about the ZIDA 4DPS let me ask it here. At the beginning of the thread you mentioned the ability of the SiS chipset to set the FSB from 25 to 66 Mhz. I'm building a maxed out 486 system with the same board and trying to set the highest speed for the CPU. So far I got 4x40Mhz or 3x50Mhz with the AMD 5X86 but the CPU won't boot at 4x50Mhz. I speculate that even if it cant start at 200Mhz it might run at 3x60Mhz. Unfortunately I cannot find the settings for 60 or 66Mhz FSB anywhere on the net, so if you have experience running your CPUs at such speeds please tell me the necessary jumper settings!

Welcome to the forum! Did you measure the Vcc coming from your CPU's socket? On my 4DPS boards, I do not have 3.6, 3.7, 3.8, nor 4.0V settings. And the 3.3V / 3.45V setting outputs 3.35 V. I doubt you will be able to get up to 180 MHz with this low of a voltage. The 200 MHz example I saw with the Am5x86 was run at 5 V, and I think one was at 4 V. So are you trying the 5 V setting? 3.35V certainly is insufficient. On my boards, I modify it with a trimmer to run a variable voltage output for the CPU's voltage.

I was unable to get a 66 MHz FSB working reliably on this motherboard.

JP18 is the PCI divisor jumper. JP18 jumpered to pins 1-2 is for the 1/2 PCI multiplier. The jumper on 2-3 is runs the PCI clock at the FSB clock.

JP19 determines the FSB frequency. Jumpers on pins 1-2 & 5-6 is 66 MHz. Jumpers on pins 3-4 is for 60 MHz.

I recommend using FPM RAM. And start out with the L2 cache disabled when determining stable settings.a

Good luck!