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Re: which 486 cpu pin is connected/talks to the cmos

Posted on 2020-06-13, 03:40

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes I see the source code you provided, I think its very relevant because irs accessing the cmos ram doesn't matter what its doing inside the ram. So under the assumption cmos read/write register error is a problem accessing the cmos ram its the same function - IO ports 0x70 and 0x71 Now I need to …

Re: which 486 cpu pin is connected/talks to the cmos

Posted on 2020-06-13, 03:04

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

For Ami bios this is what I can find for 10 beeps 10 Short Beeps Ten short beeps means that there has been a CMOS shutdown register read/write error In my case the 82C206 has cmos ram integrated. I get 10 beeps, no video, no other activity - cpu gets warm. There is not much information on google …

Re: which 486 cpu pin is connected/talks to the cmos

Posted on 2020-06-12, 23:25

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

As soon as I power on I get 1o beeps which is the cmos register read/write shutdown errror. The cmos is integrated into the opti f82c206q chip on this board https://i.ibb.co/fQwQqzX/IMG-20200410-153046.jpg Since I have a working copy of this motherboard this is what I have done first: 1. Verified …

Re: which 486 cpu pin is connected/talks to the cmos

Posted on 2020-06-12, 14:08

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So would the cpu talk directly to the south/north chipsets? I am mainly getting the cmos register error but I have also experienced other random bios beep errors so I believed this link you describe through the system bus is broken somewhere yeah I have been troubleshooting quiet a bit already, I …

which 486 cpu pin is connected/talks to the cmos

Posted on 2020-06-12, 13:41

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I am trying to find which pin on the 486 cpu socket is responsible to talking to the cmos and bios From my understanding as soon as power goes to the cpu the cpu interfaces with cmos register addresses. I am interested in finding the exact line this communication is done on. On the 486 pinouts on …

Re: Fast 486 vs entry Pentium

Posted on 2020-06-08, 10:37

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I wanted to keep overclocking out. However, AMD actually produced a rare 5x86 - 150 P75+ version. So perhaps I could include that for completeness and simulate it by overclocking the 133 version as I don't have the chip. The best I could achieve at 150 Mhz was ~16.4 in Quake. It is even slightly …

Re: Fast 486 vs entry Pentium

Posted on 2020-06-08, 09:20

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

should do the 5x86 amd clocked to 160 that is rated equivalent to p90, I got 17~ fps in quake on 5x86 @ 160 but with all tight ram timings etc

Re: When something on a board goes 'pop!'...

Posted on 2020-06-08, 09:17

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

once I had a half burned tantalum cap that looked fine form the top, but could see a small charr mark from the side. Inspect all your tantalums from all angles, you never know

Re: Creating a bootable CompactFlash card. How to do it?

Posted on 2020-05-26, 08:57

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I found you need to delete all partitions on the cf card through disk management, create new partition and format it to fat16 with disk management. Then boot dos 6.22 floppy with a vmware, mount the cf as the hard drive, fdisk it and format again through the vmware. Formatting it through my computer …

Re: cmos shutdown register read/write error

Posted on 2020-05-25, 11:03

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I finely got a cmos replacement chip, cliped off the old and installed a new one and no change still 10 beeps on boot. I went as far as comparing resistance readings on the bios chip and cmos chip from a working version of this board to the faulty one and the readings are the same. This tells me the …

Re: Biostar MB-8433UUD-A External Battery Question

Posted on 2020-05-03, 10:07

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I socketed both mine, when I was pretty bad at soldering I spent hours with a solder sucker and a soldering iron sucking out the joints and eventually did it nearly damaging the board. Second time with improved skill and a proper desolder gun with a station took about 30 minutes. There is 1 or 2 …

Re: Biostar MB-8433UUD-A External Battery Question

Posted on 2020-05-03, 08:34

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

You would have to cut the RTC outer casing and cut the positive connection to its internal battery if you want to connect a external battery. I got 2 of these boards and I know access is very limited to the RTC from the top sitting between the isa and pci slots. Unfortunately desoldering the RTC is …

Re: cmos shutdown register read/write error

Posted on 2020-04-11, 08:40

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So I was just poking around comparing resistance readings and I found something. One of the main lines one the faulty board gives me no reading to ground. On the working board it does give me a reading that slightly changes, this is ok because there is several tantalum caps on this main line. I have …

Re: cmos shutdown register read/write error

Posted on 2020-04-11, 05:35

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So I compared resistance readings on the bios pins on good and bad motherboard, resistance is exact on each pin with ground. So it seems each pin from bios is connected to the same exact path on each bios, there goes my theory about a connection from the bios to cmos being broken. Thanx for the good …

Re: cmos shutdown register read/write error

Posted on 2020-04-11, 02:04

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This kind of gives me a idea, I can try to map which bios pins connect to which cmos pins on the working motherboard, pretty time expensive exercise but what are hobbies for

Re: cmos shutdown register read/write error

Posted on 2020-04-11, 01:38

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Yes I actually tried the physical bios chip from the good board, still 10 beeps but higher pitch, maybye they are different bios revisions? I also tried the keyboard controller chip don't know why because no logic behind it but since socketed why not, same results

cmos shutdown register read/write error

Posted on 2020-04-11, 01:09

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Im fixing a 486 board that had barrel battery acid leak. From no response on boot I am now getting 10 beeps which is a cmos error. I cleaned this board, fixed corrosion, removed alot of components resistors capacitors etc as there was too much corrosion on the vias. I even found a few cracked traces …

Re: Can I solder this ceramic component be soldered back together to fix?

Posted on 2020-04-09, 06:00

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

LOL he would have to shape the leads to fit if radial too. I guess he'd better get used to pliers, then. not sure why you would need pliers for either, those wires are paper soft and legs on new caps are pretty long its a matter of sticking 1 wire through then bending the cap around to fit the …

Re: Can I solder this ceramic component be soldered back together to fix?

Posted on 2020-04-08, 00:02

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

yeah it fit no problem new capacitors come with pretty long legs, that was not a issue. nothing blew up and multimeter shows 5v over one of the cap legs so its getting juice.

Re: Can I solder this ceramic component be soldered back together to fix?

Posted on 2020-04-07, 05:54

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

From my research this is supposed to be a very stable capacitor, any reason can't use this one? https://i.ibb.co/FXFz5xQ/RC5490-100nf-50vdc-monolithic-capacitor-Image-Main-515.jpg 100nF 50VDC Monolithic Capacitor I guess you'd have to pass on it if you had an irresistible prejudice against pliers. …

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