Sergey Kiselev

This system doesn't appear to use a 8255 PPI, which, among other things, is used for the keyboard interfacing on IBM PC, IBM PC/XT, and most clones. So I suspect...

Oh. I missed it. In this case, it is possible that the keyboard just uses standard XT protocol (not an AT one though! An AT keyboard will not work with...

The keyboard code in 8088 BIOS should be XT compatible... Below is partial disassembly of the INT 9 / IRQ1 handler from the BIOS you've attached. Looks mostly XT compatible....

Unless Ericsson/Nokia use a keyboard protocol very different from IBM PC/XT (unlikely), it wouldn't be possible to control the keyboard LEDs from the computer. The communication protocol is unidirectional -...

I am not sure how easy it will be to implement the INT 10h CGA support in Ericsson BIOS. There are some "holes" in the BIOS, so potentially, these can...

I don't see any references to port 0x04 in the code. It must be specific to Ericsson step/one computer. Ignore that recommendation.

Looking at the motherboard, I see there is a 8251 USART right next to the 8255. And that is in addition to the 8250 UART at the top left corner,...

A bit more of disassembly. Subroutine at F000:E76A appears to be a simple "beep" routine. It generates 500 pulses to the speaker. Not very important ;) ``` F000:E76A 50 PUSH...

The BIOS uses a loop to initialize 25h I/O ports (table at C07D). The corresponding USART initialization instructions are: ``` ; Set USART to command mode: configure sync operation, write...

That's what I am trying to figure out. It should be possible to simply initialize the USART and enable receive. It is quite possible that the communication to the keyboard...