Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-05-01, 21:40

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

That I can tell, A B and C never go low A connects to 183, B connects to 182 and C connects to 181. pins 4 and 6 remain high while 5 remains low. One thing also I have not checked yet is if DRQ2 is actually reaching the chipset. I've only probed from the ISA bus. That would go to pin 149 in one way …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-05-01, 19:33

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

U24 is a 74LS138N 3-line to 8-line decoder. Okay so if I'm reading that right, DRQ2 is the floppy controller sending a DMA request to the chipset ("Mr 85C461 can I plz use DMA channel #2?"). The chipset responds back with DACK2 ("Yes device, you can use DMA channel #2 until I say stop.") If I'm …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-05-01, 17:59

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

So I double checked to see if the scope was fast enough to trigger and display activity on DACK2 using the test board and yes I can see it pull low on floppy boot (and I just discovered that the vertical adjustment on channel 1 has stopped working so I'm only able to watch one pin at a time using …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-05-01, 16:44

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm sure this has already been covered, but on the controller card, does it have IDE ports with anything plugged in to them, and do they work correctly (this should test whether anything can get data across the bus from that particular card)? Can you post a photo of the card? It does and every time …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-05-01, 03:33

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Do you know if those DREQ and IRQ jumpers change anything? They don't seem to change anything at all when moved around. n IMD, does the capital 'Z' at the top of the screen (where it says fwRZd) change to lower case if you move the heads off of track 0 (try pressing '+' to go up one track and '4' …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-29, 00:47

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

[edit bad phrasing here] One differences I spotted is the hard wired link for 1x CPU multiplier on JP1 down by the BIOS chip. It's currently wired as 2-3, which the silkscreen says is 1x and the dosdays listing shows as 2x. What does IMD http://dunfield.classiccmp.org/img/index.htm do on either the …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-28, 01:44

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

What happens if you try to format a floppy, with no command line switches? Does it say what capacity it's going to try before failing? Had an odd case on another thread where the BIOS menus had the correct settings, but the registers ended up with the drive as a 360k 5.25". It will format as 1.44mb …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-27, 13:41

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I'm not using a CF card. I'm using a DOM. Anyways for the purpose of testing the entire IDE ribbon cable is unplugged and only one floppy drive is attached and configured in the BIOS.

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-27, 01:45

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I am not positive by any stretch that this is the correct BIOS for this revision board. I do not have an EPROM image to burn and compare against. So I remembered that I have a POST card that latches indicators when IRQ's and DMA's are triggered and after verifying that I should see IRQ6 and DMA 2 …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-27, 00:36

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Not that I can identify. So I beeped out DRQ2 and DACK2 and they both seem to be intact spanning across the bus. DRQ2 originates from U8 pin 13 (74F151BN) and DACK2 comes from U24 pin 13 (74LS138N) and both chips seem to have their inputs all beep through to the 85C461, except for Z̅ on the 151. I'm …

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-26, 23:54

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Try a different I/O card. I've tried five different cards. It might sound silly since you have tried the floppy cables I've change the cables twice. The drive, cables and controller are tested working.

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Re: 486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-26, 04:28

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Good news I guess, I opened Procomm and setup my serial tester in loopback mode and even at the highest baudrate both ports worked fine. https://hosting.photobucket.com/images/a166/ballsandy/IMG_8349.JPG Here's a photo of the board. *Go here and right-click to view the full-size image* Aside from a …

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486 will not boot from floppy; will not read from floppy either

Posted on 2021-04-25, 22:53

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I put together an ASUS ISA-486SV2 Rev. 3.1 motherboard with a Trident VLB video card, PRIME 2 chipset disk and I/O ISA controller with a 66mhz DX2 and I can't make it work with the floppy drives. Put a bootable floppy in and while it will light the drive and spin the motor it will just sit there …

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Re: games that are better on a Macintosh

Posted on 2021-04-01, 00:23

by

by CelGen

in Macintosh Emulation

in Macintosh Emulation

Huh. I had no idea there was ever a 20th anniversary release. Nevermind then.

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Re: the signs that a forum is dying

Posted on 2021-03-11, 04:32

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by CelGen

in Milliways

in Milliways

Every forum I've been on that died, died because the all consuming leviathan of politics finally visited it. Sounds like you've been on some forums with fairly dramatic downfalls! it's true that in forums where the dominant form of discussion is 'political', should 1 side 'win' by taking control, …

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Re: games that are better on a Macintosh

Posted on 2021-03-10, 03:14

by

by CelGen

in Macintosh Emulation

in Macintosh Emulation

Pegasus Prime is listed but it's a remake and really has nothing in comparison to the original game and ironically the PC release (on steam) is the better version due to content being re-added that was omitted from the mac release. That said, The Journeman Project/The Journeyman Project Turbo! plays …

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Re: Bought these (retro) hardware today

Posted on 2020-10-12, 22:32

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by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Mac Classics need every lytic capacitor on the logic board changed, first and foremost. None work anymore with their original caps.

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Re: Bought these (retro) hardware today

Posted on 2020-10-12, 20:27

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by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

Apricot XEN-i - British built 286 AT clone. Came with the trackball mouse and the funky keyboard with the LCD and programmable buttons like a Logitech G15. https://hosting.photobucket.com/images/a166/ballsandy/CGS_10135.JPG?width=1920&height=1080&fit=bounds https://hosting.photobucket.com/images/ …

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Re: Unacceptable OpenGL Performance

Posted on 2020-01-11, 04:11

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by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

I am aware that this thread is now just over three years old however I was recently able to circle back around to this machine and found the answer to my performance issues: That IS the best there is. I totally skipped a page in the manual that covers this. Sorry guys. Sure, the card supports the …

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Re: What Hard-drives have the best retro "ticking" sound ?

Posted on 2019-12-25, 04:29

by

by CelGen

in Marvin \ General Old Hardware

in Marvin \ General Old Hardware

The The 225's and 251's made that great hollow knock while the 3.5" miniscribes made that very familiar stepper motor whirr.

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