Problems with BIOS for Migitronics TK-82C491/386-4N-D02C motherboard...

Posted on Yesterday, 13:32

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I got one Migitronics TK-82C491/386-4N-D02C board with soldered Am80386DX-40 CPU, missing BIOS chip and no cache chips. The board is in pretty good visual condition (no broken traces, no battery leakage, clean and with no missing elements, except the BIOS and cache chips) and I thought - this will …

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Re: [SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on Yesterday, 07:28

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I've just checked my other old VLB I/O+ATA controller for 486 systems and it also has separate "IOCHRDY" jumpers (factory populated) for both the ATA channels, but it also has jumpers for setting the PIO modes - 0 to 3. It was factory set to PIO mode 0 and I/O ch. ready - disabled, now I fixed this …

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Re: [SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on Yesterday, 05:44

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Aha, this makes sense. And it's actually backwards of what I thought according to vstrakh 's explanations. Right now I'm using 250 MB HDD attached to this ISA controller and this hard drive supports PIO mode 3 . When I find some time, I'll test drive's transfer speed with and without IOCHREADY …

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Re: What do you use your ramdisk/ramdrive for?

Posted on Yesterday, 05:14

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Back in the 80386/80486 days my home computer had only 4MB of RAM (the RAM modules pretty expensive back then), so other than a one-time test, I've never used DOS RAM-drives. Later hard drives got bigger and fast enough (and win 95 came) that I forgot that there was such a DOS tool. Nowadays old FP …

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Re: [SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on Yesterday, 04:33

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Thanks everyone for sharing details about the ATA interface that I never bothered to know. Correct, the IDE ribbon cable is basically just extending the ISA bus to the hard drive. The actual controller is the PCB on the bottom of the drive. IDE means integrated drive electronics. (for ISA …

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Re: [SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-12, 19:02

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I traced back this "IOCHREADY" signal on the controller's PCB. One of the two jumper pins (I soldered them some time ago, just to make it look "complete") is directly connected to ISA slot A-10 pin (I/O CH RDY) and the second pin goes directly to ATA pin-header on pin 27 (IOCHRDY), so no controller …

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Re: What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-11, 08:14

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

This line is driven by the devices, the chipset will be listening it to give devices more time. It's not that it is required. It's not really needed at all unless you're running some really slow device (ISA card or ancient IDE drive) on a faster ISA bus and it's glitching at those speeds. …

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Re: What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-11, 08:10

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ok, so this is probably more of a CPU/chipset/ISA bus related setting. But still, in which case I may need it? Slower CPU, slower ISA bus setting, slower HDD?

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Re: What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-11, 07:54

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Input Output Control Hub or the South Bridge in most cases controls access to all IO systems on the Motherboard from Serial through to Drives, pretty sure USB along with all other Input/Output systems are part of the south bridge in newer modern systems. In older boards USB/Firewire is controlled …

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[SOLVED] What does "IOCHREADY" mean and what is its purpose?

Posted on 2024-05-11, 07:22

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm using some ISA I/O+ATA controller in my old 386SX system and on its settings jumper are missing two pins corresponding to "IOCHREADY (Optional)". What does this IOCHREADY mean and what is the purpose of this setting? All mechanical hard drives I have ever used with this I/O+ATA controller have …

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In search for CHGDMI.EXE and MODEL.DMI for IBM Aptiva 2139

Posted on 2024-05-11, 07:06

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by analog_programmer

in Marvin \ Software

in Marvin \ Software

Hi, retro computers fellas! I flashed the BIOS of IBM Aptiva 2139 motherboard (V66XA) with Acer's BIOS because of newer CPU support and now I reverted back to it's original IBM's BIOS, and of course serial number in BIOS now is 00000000. Before I flashed the Acer's BIOS I wrote down the original …

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Re: M912 with 1 MB cache

Posted on 2024-05-10, 09:43

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

It was set to 512KB because the 1MB wasn't working right. It is labelled as 1.4 I have determined that the second bank just isn't working at all. I am going to sell this as a working 512KB board and get something with 1MB Ahhh, now I see. I'm sorry, I just tried to help by what I saw on the picture …

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Re: Full recap of Chieftec CFT-650-14C PSU - I need some info about its electrolytic capacitors

Posted on 2024-05-09, 12:49

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

That was what I was thinking about when I mentioned "modular or interchangeable". That being said, and on further thought, maybe there is a valid reason for that monitor circuit to not assert PG. Maybe it's detecting an issue with regulation, ripple, whatever else (I don't know how sophisticated …

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Re: Full recap of Chieftec CFT-650-14C PSU - I need some info about its electrolytic capacitors

Posted on 2024-05-09, 11:53

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Another idea came to my mind. If I take a controller chip with a well documented circuit from another PSU (I have a couple of quite old working power supplies with lower power - up to 400 W), I can make an additional small PCB to be wired-in and which will be responsible only for monitoring the …

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Re: Full recap of Chieftec CFT-650-14C PSU - I need some info about its electrolytic capacitors

Posted on 2024-05-09, 11:22

by

by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Maybe I'm talking nonsense here, but a monitoring circuit seems like it would be modular or interchangeable in this kind of scenario, if all it does is make sure all output voltages are in range and set PG low or high accordingly. Alternatively, at least setting PG assertion on a delay to give time …

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Re: Full recap of Chieftec CFT-650-14C PSU - I need some info about its electrolytic capacitors

Posted on 2024-05-09, 09:14

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The "power good" signal to +5 V line dirty hack totally worked. Now I officially have a "100% chinese quality" ATX PSU of a respected brand. I hope the new Samxon GF caps will hold up well in +5 V lines at least for a couple of years. And for my surprise even in shi*ipedia this "power good" mod is …

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Re: M912 with 1 MB cache

Posted on 2024-05-09, 07:10

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So I was using 128kx8 DIP modules for cache as well as the tag. The manual specifies a 64x8 DIP for tag, could this be the cause? I though I could always use a bigger tag than needed. However, once again, the 128kx8 tag works for tag in 512kB mode and that only needs a 32x8, so I don't know. The …

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Re: Full recap of Chieftec CFT-650-14C PSU - I need some info about its electrolytic capacitors

Posted on 2024-05-07, 12:48

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Ok, as usually I'm asking and later I get answers by myself. So this "power good" +5 V signal is not related to motherboard's voltages, but formed internally by PSU's controller (if all the other voltages are presented as within the specs to the controller's chip ant there's no triggered protection …

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Re: Full recap of Chieftec CFT-650-14C PSU - I need some info about its electrolytic capacitors

Posted on 2024-05-07, 09:31

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by analog_programmer

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Finally I replaced all the electrolytic capacitors except mains filter capacitor 390 uF/400 V and one very little capacitor which is 0.33 uF. Tested the power supply without any load and it starts, gives all the +12 V, +5 V, +3.3 V, -12 V etc. lines, except the "power good" signal (grey wire), which …

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Re: Need some help. My GPU doesn't work on socket 7 MB but it works on socket 370

Posted on 2024-05-06, 19:56

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by analog_programmer

in Marvin \ Video

in Marvin \ Video

On this M571 motherboard jumper JP3 is for enabling (2-3 pins shorted)/disabling (1-2 pins shorted) integrated VGA. Did you try to disable it?

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