IBM PS/2 Model 30 286 Keyboard Issues

[Oloryn]

Hello all,

I recently picked up an IBM PS/2 Model 30 286. Despite being filthy the machine looks to be in relatively good shape. So far I've successfully booted to the 30MB hard drive once. However, I now continue to get the following error codes in POST: 303, 163, and 164. Codes 163 & 164 are related to the clock chip (Dallas) being dead. I have some replacements somewhere, need to find them. The 303 code states "Keyboard or system board error". I cannot hit F1 to boot from floppy (which I'm uncertain if it's working yet, haven't made it that far) and so the system sits on the screen indicating press F1 to continue. I've tried several PS/2 keyboards all give the same error. I have double checked the Guide to Operations and verified that I am plugged into the correct port. I currently have only the floppy drive connected, and nothing in the ISA slots. I'm starting to pull my hair out at this point. As always any and all help is greatly appreciated. Thanks.

 

[modem7]

With the keyboard removed, do you see a 301 error instead of the 303 ?

 

[modem7]

Codes 163 & 164 are related to the clock chip (Dallas) being dead. I have some replacements somewhere, need to find them.

Might the replacement also have a low/depleted battery. I.e. substitution of bad with bad ?

Per [here], note that a so-called 'drop in replacement' may be unsuitable.

Consider the well published technique of disconnecting the DS1287's internal battery, then attaching a new battery.

 

[Oloryn]

With the keyboard removed, do you see a 301 error instead of the 303 ?

Unfortunately with the keyboard disconnected it still gives a 303 error.

Might the replacement also have a low/depleted battery. I.e. substitution of bad with bad ?

Per [here], note that a so-called 'drop in replacement' may be unsuitable.

Consider the well published technique of disconnecting the DS1287's internal battery, then attaching a new battery.

I did find my stock of Dallas RTC modules (I use the ones designed by Necroware) which use the Dallas DS12885S chip (or Bencmarq equivalent) However the errors persist whether the original Dallas module or the replacement is used.

I also have a typo in the initial post, the errors were 303, 162, and 163. With the replacement installed the errors are 303, 161, and 163.

Could the fault be the keyboard controller chip? This is just a hunch. I'll try and get the board out of the system in the next day or so and inspect for cold solder joints as well.

 

[modem7]

With the keyboard removed, do you see a 301 error instead of the 303 ?

Unfortunately with the keyboard disconnected it still gives a 303 error.

It really does suggest a motherboard fault related to the keyboard interface.

I did find my stock of Dallas RTC modules (I use the ones designed by Necroware) which use the Dallas DS12885S chip (or Bencmarq equivalent) However the errors persist whether the original Dallas module or the replacement is used.

1. The model of replacement may not be compatible with the motherboard.
2. If it is compatible, maybe what you used contains a low/depleted battery.
3. If it is compatible, and the battery within is good, you need to use the 'IBM PS/2 Model 30 286 Starter Diskette' to clear the 16x errors.

I also have a typo in the initial post, the errors were 303, 162, and 163. With the replacement installed the errors are 303, 161, and 163.

From the 'PS/2 Model 30 286 Guide to Operations' document (found online):



Of course, certainly the 163 won't be able to be removed if there is no keyboard functionality.

Unfortunately with the keyboard disconnected it still gives a 303 error.

Could the fault be the keyboard controller chip?

Without seeing the motherboard circuit diagram, and the POST code that triggers a 303 error, a definitive answer is not possible. Note that the keyboard interface circuitry contains more than a keyboard controller chip.

Just in case you are unaware: The web page at [here] indicates that the chip is an 'Intel 8042/8742 K/B Ctrl.' Calling the 8042/8742 a keyboard controller is misleading to some people. The 8042 (8742 is the EPROM equivalent) is a general purpose microcontroller that gets programmed with custom code according to the task. For example, there may have been suitably programmed 8042/8742 used in early microwave ovens. In the PS/2 Model 30 286, the 8042/8742 contains code (possibly IBM authored) that makes the 8042/8742 suitable to perform the function of a keyboard controller on a PS/2 Model 30 286 motherboard.