Re: What is the function of this card?
Posted on 2020-02-01, 22:07
It does look like some sort of bus termination setup but AFAIR the non-pro Pentiums were single socket only, so why would it even need one.
Re: PC speaker connector with 3 with connected pins. How to use?
Posted on 2020-02-01, 22:02
I'm measuring a series of square wave-looking signals on pin 22 in the first few seconds after powering on. After that it's steady for a bit (at low voltage), then a few more pulses and then steady again. And that's pretty much all you can do with a scope. It tells you the CPU is running, but as to …
Re: Inaccessable Bios, due to unknown password and RAM PARITY-ERROR
Posted on 2020-01-31, 19:08
Wilius wrote on 2020-01-31, 18:59: I hope you can see the pictures. I wasn't sure which file licence I should pick. Fifth entry from the bottom, says "Memory parity check" - set it to Disable.
Re: How to run your FPU asynchronously on 386 motherboards
Posted on 2020-01-31, 19:01
Somehow I doubt they can ignore anything, especially if they clocked by a different oscillator. Intel387 TM SX MATH COPROCESSOR datasheet, 1.1 Pin Description Table: CKM - input - CLOCKING MODE is used to select synchronous or asynchronous clock modes. CPUCLK2 - input - CPU CLOCK input provides the …
Re: Inaccessable Bios, due to unknown password and RAM PARITY-ERROR
Posted on 2020-01-31, 18:56
You don't seem to know what parity is. Parity checking is a 9th bit on the RAM module for each byte that is set to either odd or even and is checked when reading from RAM. It requires RAM with the additional 9th parity bit, of course. Actually, it's bits 32-35 (counting from zero). But I'm not here …
Re: Inaccessable Bios, due to unknown password and RAM PARITY-ERROR
Posted on 2020-01-31, 17:18
You can not have a parity error with RAM that has no parity! Sure you can - socket/RAM stick corrosion, or broken mobo traces (or battery spill corrosion) can very easily confuse the BIOS detection code. Since this is a 486 system I would also re-seat the CPU (and in general make sure it's not …
Re: How to run your FPU asynchronously on 386 motherboards
Posted on 2020-01-31, 17:05
Non-Intel FPU simply ignore the selection signal and always use CPU clock - which, AFAIK, has to be always present to have the bus/io at the same speed, after all the CPU has to be able to transfer data and instructions in and out of the FPU. So that 25MHz FPU might simply be overclocked now. A good …
Re: Inaccessable Bios, due to unknown password and RAM PARITY-ERROR
Posted on 2020-01-31, 16:04
It appears, there is no option, that allows me to disable parity in the BIOS settings. What am I supposed to do now? Do you need screenshots? Well, maybe you do have a RAM parity error, as in, one of the RAM sticks you have is fauly. That would explain why the computer stopped POSTing and why the …
Re: When was booting from cd-rom possible ?
Posted on 2020-01-31, 14:06
February 28, 1989 😀
Re: Stuck ST-177I drive
Posted on 2020-01-31, 14:01
After spinning it for quite a while it still isn't spinning up, but it does spin sort of freely when I spin it by hand. It stops directly after I stop spinning though. You can feel the platters spin? You sure about that? Because if it does spin at all, it's not stuck - this is caused by the heads " …
Re: Help needed with repairing missing capacitor on SiS6326 PCI video card
Posted on 2020-01-31, 13:26
OK, I suppose 100nF vs 10nF is not a big deal either then. I'll go with the 100nF 16V anyway. Finally, why is it a bad idea to bridge this and just close it? Asking out of sheer curiosity :D You can even use a THT (through-hole) capacitor instead of SMD one, just keep the leads as short as possible …
Re: Help needed with repairing missing capacitor on SiS6326 PCI video card
Posted on 2020-01-31, 12:22
100nF 16V 10% 10nF 25V 10% Which of these is the safer bet then? 100nF 15V? Both are OK. There is not going to be more than 12V there simply because the PSU doesn't have any higher voltages on it's output rails, and there aren't any DC-DC converters on the mobo or the card itself. In fact even 12V …
Re: PC speaker connector with 3 with connected pins. How to use?
Posted on 2020-01-31, 11:15
It was always missing. But there are some jumpers for setting the keyboard controller to "internal" and "external". The newer chipsets can emulate these, true, but I've never seen mobos with an empty socket. Usually the manufacturer would just not solder it at all, and the jumpers would be …
Re: Help needed with repairing missing capacitor on SiS6326 PCI video card
Posted on 2020-01-31, 10:06
Now I need to: a) Replace it with a suitable rating SMD capacitor (or a ceramic capacitor using the via's just below, as it would be more suitable for my soldering skills..) - and this is where I need advice as to what rating it could be? b) Just bridge the via right below the capacitor and bypass …
Re: Just bought a 8900D with some really strange memory on it
Posted on 2020-01-30, 23:59
I've seen Trident-based cards with 12 DRAM chips on sale - the photos weren't all that good but I think the RAMs were 256x4 connected as 3 bits+3 bits+2 bits. Why? To be able to use rejected dies that had bad cells or even more major issues. So it would seem some VGA manufacturers tried extreme cost …
Re: PC speaker connector with 3 with connected pins. How to use?
Posted on 2020-01-30, 23:49
U30 socket (left bottom side) is empty - did you remove that chip for some reason before taking the photo? Typically this is where keyboard controller is. If it's missing the mobo might not boot at all, these chips provide (as a secondary function) control over the CPU reset line. Might very well be …
Re: PC speaker connector with 3 with connected pins. How to use?
Posted on 2020-01-30, 11:16
I ordered a POST BIOS card from China last week but who knows how long it will take to arrive, so I will try to measure the lines you mentioned. What kind of signals should I be seeing? Start with BIOS chip. One of the /CE (/CS) and /OE lines might be connected directly to ground so if that's the …
Re: SCSI2SD - Configuration of SD Card to use multiple partitions
Posted on 2020-01-30, 08:37
I’m having trouble with my SCSI2SD adapter… Does anyone know how to format a 4 GB SD card so that I can use the multiple drive feature for 4 x 1 GB drives in the SCSI2SD? In short, you don't. SCSI2SD doesn't need or use any format, it will use the card as a block device and you only specify the …
Re: PC speaker connector with 3 with connected pins. How to use?
Posted on 2020-01-29, 22:18
I had two 486 mobos that didn't POST or beep when there was something wrong with the RAM sticks. So having a PC speaker working is not exactly a great help in diagnosing issues. A POST card will serve you much better. Since you have a scope, probe the ISA slot signals - reset, clocks, address/data …
Re: Need help with old 486 motherboard only running CPU at half speed.
Posted on 2020-01-28, 23:26
However, my SX-16 feels a bit under-appreciated after your mentioning of SX-20 :) Huh. I stand corrected then. Perhaps it's some special version, I know Intel manufactured 386DX for a looong time with pitiful (on paper) clocks for military applications. This seems to be a '92 CPU - by that time …
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