Keyboard difference between 5155 and 5160?

[Trixter]

I'm working on a programming project with some friends and one of the things we're doing is hooking the keyboard interrupt (handling the keyboard ourselves is a requirement of what we're doing). On the 5160, trapping int 09h/IRQ 1 works as expected. On a 5155 we're using for testing, it does not -- IRQ1 never seems to fire (ie. keyboard is dead).

Before I delve much further into this, was there a fundamental difference between the 5160 and 5155 in terms of keyboard handling in the hardware and/or BIOS? If so, what is the difference? Both the 5155 and 5160 use variants of the same motherboard, and although the 5155 keyboard uses an RJ11 to connect to the front, in back it's a normal 5-pin DIN and, I'm assuming, XT signaling.

 

[Great Hierophant]

I assume you didn't get a 1xx or 3xx error on bootup and the system board and keyboard passed XT Advanced Diagnostics. 5155 and 5160 use the same BIOS. RJ11 has four contacts, and the XT DIN uses only 4 of the 5 pins, so I would think that the physical connector is the only difference between them.

I think something on the 5155 board is faulty. I had a similar issue with an IRQ not firing on a Roland MPU-401 I have. The device otherwise worked fine but when it should have sent an IRQ (2/9) to indicate that it had MIDI data for the computer, the computer would never receive it. Virtually all programs relied on this behavior, and none would give me the data dump being sent from an MT-32 via the MPU-401's MIDI IN. However, a program that used straight polling worked. I replaced the IC on the interface card where the IRQ signal was being routed from the MPU-401 BOB and the ISA connector and the IRQ started firing again.

 

[modem7]

Before I delve much further into this, was there a fundamental difference between the 5160 and 5155 in terms of keyboard handling in the hardware and/or BIOS?

The 5155 has the same motherboard (including BIOS) that is found in the first version of the 5160.

Maybe your 5160 has the second or third BIOS revision. If so, upgrade the BIOS in your 5155 from the first to the third BIOS revision (a valid action) and see if that resolves the issue.

BIOS info at http://www.minuszerodegrees.net/5160/bios/5160_bios_revisions.htm

 

[reenigne]

Person who wrote the buggy code here. I suspect the 5155/5160 difference here is one of timing - I suspect that either the key used to start the program is released quicker on the 5160 or that the program loads faster on the 5155 and the "key up" scancode from that keypress is being intercepted by the program on the 5155 only, and that is what is confusing it.

 

[JimWilliams]

How do you upgrade a BIOS? Where do you get a later BIOS to use in the upgrade? thx-Jim

 

[modem7]

Lots of IBM 5155 and 5160 information at http://www.minuszerodegrees.net

How do you upgrade a BIOS?

In the IBM 5155 and 5160, you need to remove chips U18 and U19, and then insert replacement U18 and U19 chips, ones that contain the new BIOS version.
Replacement U18 and U19 chips can be created by 'burning' images of the new BIOS into suitable EPROMs.

Where do you get a later BIOS to use in the upgrade?

Images at http://www.minuszerodegrees.net/bios/bios.htm