Troubleshooting An Obscure IBM PC/AT Clone

[Windows2000]

Now that I have found some time to myself I decided to work on my clones this past week and have found some success in getting them operational again, but I now have come to a snag in the road that I have been trying to work against for a good hour. So now I ask the community for their input. Attached below is exactly how far I have come to a PC Edge (Not Leading Edge) 286 AT clone.


Obviously some tweaks in the BIOS (Or as it said, setup program) are needed but the screen displays no help on how to get into the program, I've looked online and have tried several different key combinations but no luck. I've switched keyboard three times to make sure it wasn't a mechanical problem but I still get the same result. Striking F1 only replies something about a missing boot disk, even when there is a boot floppy in the drive or a hard drive connected. Then comes the diskette drive problem, as I can not have any drive connected AT ALL and it still displays a "track 0" error. For this I have tried two different 3.5" floppy drives and one 5.25" floppy drive with no chance in the results here either. I have replaced the CMOS battery already but there was no change, I have tried restarting it with no CMOS battery at all and there was no chance even when waiting for 10-15 minutes.

Basically I can't continue any further than this and I really want to get this system up and running again but I am not sure what to do with this. I cannot find any documentation on a PC Edge 286 AT either, so my assistance is very limited.

 

[Al Hartman]

You might need an actual setup program on a floppy disk. Not all systems back in the day contained the setup software in ROM. I would think that it's expecting a 5.25" 1.2mb drive as Drive A:. Check that you're using the correct kind of floppy cable and that your drive is set to DS1 and going to the connector with the twist in the cable. The twist needs to be to the left of the cable, not the right. If the twist is on the right side, that's an MFM drive cable.

This thread has a setup file that might work.

http://www.vintage-computer.com/vcforum/showthread.php?24597-How-to-get-into-Bios-Tulip-DC-286

You might also try jumpering the floppy to DS0 and attaching it to the connector without a twist.

 

[Windows2000]

You might need an actual setup program on a floppy disk. Not all systems back in the day contained the setup software in ROM. I would think that it's expecting a 5.25" 1.2mb drive as Drive A:. Check that you're using the correct kind of floppy cable and that your drive is set to DS1 and going to the connector with the twist in the cable. The twist needs to be to the left of the cable, not the right. If the twist is on the right side, that's an MFM drive cable.

I'm sure the cable is on the right connection but I don't believe I would have a disk for this system. If it's obscure beyond the reaches of Google search, how would I go about a software disk? Does it just need a disk for the Pheonix BIOS version?

 

[Al Hartman]

Go back and look above, I posted a link to another thread with a Phoenix setup program.

 

[modem7]

You can be pretty sure that "please run SETUP program" means that you'll need to boot from a DOS boot floppy that contains the SETUP program, and then run the SETUP program.

Your machine has an early BIOS - maybe even a generic setup program, like GSETUP, will work.

With the CMOS/SETUP configuration lost, you may find that the only boot options are a 360K floppy or 720k diskette. That is what happens with the IBM AT.

 

[Stone]

You can be pretty sure that "please run SETUP program" means that you'll need to boot from a DOS boot floppy that contains the SETUP program, and then run the SETUP program.

Nah, when a Phoenix 286 BIOS displays that message it's referring to the CMOS setup.

Windows2000, try pressing CTRL + ALT + ESC and see if that doesn't get you into the setup.

 

[SomeGuy]

I have a similar Phoenix 286 BIOS and it does not have a built in setup program. To configure the CMOS I have to run a setup program from disk.

From my experience, usually 286s are generic enough it is possible to run a number of different "ATSETUP" type programs to configure them. At worst, some setup programs might show optional features that the BIOS does not actually support. For example, with my Phoenix BIOS it is not possible to specify a hard drive type other than what is listed in the BIOS hard drive table.

It should be possible to boot a DOS floppy even if the floppy type is set wrong. If you are using a 1.44mb drive, try both 1.44mb and 720k disks, at least one should work. The track zero error may appear until the drive types are set correctly.

With the drive attached, can you see or hear it doing the seek test at boot? Does the drive light come on when you hit F1?

Are you using the cable that came with the machine? Is it a standard twisted cable? Have you tried a different cable? Is the FDC chip on the motherboard or a card? If it is on a card, have you tried another card?

 

[Windows2000]

Nah, when a Phoenix 286 BIOS displays that message it's referring to the CMOS setup.

Windows2000, try pressing CTRL + ALT + ESC and see if that doesn't get you into the setup.

That didn't work.

I have a similar Phoenix 286 BIOS and it does not have a built in setup program. To configure the CMOS I have to run a setup program from disk.

From my experience, usually 286s are generic enough it is possible to run a number of different "ATSETUP" type programs to configure them. At worst, some setup programs might show optional features that the BIOS does not actually support. For example, with my Phoenix BIOS it is not possible to specify a hard drive type other than what is listed in the BIOS hard drive table.

It should be possible to boot a DOS floppy even if the floppy type is set wrong. If you are using a 1.44mb drive, try both 1.44mb and 720k disks, at least one should work. The track zero error may appear until the drive types are set correctly.

With the drive attached, can you see or hear it doing the seek test at boot? Does the drive light come on when you hit F1?

Are you using the cable that came with the machine? Is it a standard twisted cable? Have you tried a different cable? Is the FDC chip on the motherboard or a card? If it is on a card, have you tried another card?

When I connect any floppy drive their lights are on permanently. No drive activity is done during the start-up, nor whenever I press F1. I am not entirely sure if the cable came with the machine or if it was added later as I received this computer from a friend last year. It is not a twist cable but I can possibly try another one. The connector is card-based but I do not have another card to test with at the moment.

 

[Chuck(G)]

When I connect any floppy drive their lights are on permanently. No drive activity is done during the start-up, nor whenever I press F1. I am not entirely sure if the cable came with the machine or if it was added later as I received this computer from a friend last year. It is not a twist cable but I can possibly try another one. The connector is card-based but I do not have another card to test with at the moment.

Well, yes--you probably should try a cable with a twist. But even more importantly, you should check to see if your cable is installed backwards. This is why--floppy drive signals are what is called "active low". That is, each signal line is pulled up by a resistor to +5V when inactive. When the controller or the floppy wants to signal, the line is pulled by the output of the associated driver gate to somewhere usually less than 1 volt. This includes the motor control and drive select lines (as well as all other control signals). Every other conductor in a floppy cable is connected to 0V/ground. This prevents, to some extent any crosstalk between adjacent signal pins. Now if you connect the cable upside down/reversed, all of the drive signal lines are now connected to 0V, and the drive looks like it's selected. If you have floppy disk in the drive, the motor will even spin. It will also clobber the track that the heads happen to be on, so be careful.

It's extremely rare for a controller to fail in such a manner as to pull the signal lines to ground.

 

[Windows2000]

Well, yes--you probably should try a cable with a twist. But even more importantly, you should check to see if your cable is installed backwards. This is why--floppy drive signals are what is called "active low". That is, each signal line is pulled up by a resistor to +5V when inactive. When the controller or the floppy wants to signal, the line is pulled by the output of the associated driver gate to somewhere usually less than 1 volt. This includes the motor control and drive select lines (as well as all other control signals). Every other conductor in a floppy cable is connected to 0V/ground. This prevents, to some extent any crosstalk between adjacent signal pins. Now if you connect the cable upside down/reversed, all of the drive signal lines are now connected to 0V, and the drive looks like it's selected. If you have floppy disk in the drive, the motor will even spin. It will also clobber the track that the heads happen to be on, so be careful.

It's extremely rare for a controller to fail in such a manner as to pull the signal lines to ground.

Sorry for the late reply, I have found myself in some unwanted business and haven't had the time to go back to the system yet but I might try tonight. I don't think I have a twist cable but can try messing with the connection and see if I can get any other reaction from the system.