mahmood,

When I look at the other end of the pc keyboard in old mother boards I almost always find a chip 8048.

My experience has been that old Motherboards had an i8042 and the keyboards had the i8048. I have found 8742's in old motherboards (eprom) but not that many.

PC Keyboards evolved to AT Keyboards using an i8051.

No matter, an 8048 has a lot in common with the 8051 (instruction set) but is not all that close architecturally. It's address space was limited and had to be banked in pages. It's stack was fixed and not deep.

It's more like a GI - (pre-microchip) PIC in architecture.

Now the 8042 is just an 8048 with a Host Port and that makes it pretty interesting.

regards,
p