I have an old keyboard that uses an 8051AH IC along with a HC14, a HC14T and 3 74HCT4051 IC's.
I am trying to rebuild part of this (not all of it) and have the circuit diagrams for the keyboard.
I don't need the 40 pin version (as used in the keyboard)as I do not require all the inputs ( so I was wondering if I can just replace it with a 89c2051.
I know the 8051AH is factory programmed ROM - I presume this is from the IC manufacturer and not the hardware manufacturer into which it is installed.
With that in mind, will I need to program the 89c2051? And if so, will I be able to read and copy the programming from the old 8051AH with suitable PIC equitment?
Or is it literally a plug an pray drop in replacement?
Not sure if you can pull the content from a mask programmed device. Assume you're going to need to code your own solution, and if that's beyond you, move on.
Fair enough.
Does that mean 8051HA's could be programmed differently from each other despite being factory ROM's?
If that is the case I will have to salvage the original IC's.
Thanks.
The circuit I am working from is here chrisacorns.computinghistory.org.uk/.../Acorn_A5000TRM_Drawings.zip
I am only interested in the mouse input to the keyboard output.
As a buyer of a mask programmed 8051 I would send Intel a HEX file for the device I want them to build me, it would be a unique part for me, and not like any other mask programmed devices they sold to other people.
The mouse appears to apply X and Y quadrature encoded signals to the 8051, along with 3 buttons. Not sure how that was converted into the keyboard output stream. Sure Acorn documented it somewhere, or could be inferred from analysis.
Most helpful, thank you.
Your right about the quadrature nature of the mouse and the 3 button signals. They use 7 of the 9 pins available in the mouse leaving GCC and Gnd.
The keyboard, unlike PS/2 (which sends data and clock) sends tx and RX.
I will pay with salvaged chips I think.
Regards, Jon.