Assembling an Apple-1 computer – Part 4

My Apple-1 computer needs a parallel ASCII keyboard to work. My S-100 systems could use a parallel ASCII keyboard as well. AFAIK parallel ASCII keyboards have not been made for a couple of decades.

I have a NOS parallel ASCII keyboard however it will require some work to get it setup correctly; this got me to wondering if I could use a more modern PS/2 style keyboard; this lead to me reinstalling my MikroE c compiler (for PICs) and digging out my EasyPIC5 development board.

I am sitting here astonished at how east this was to put together; the MikroE c compiler supplies a number of libraries including a 4-Bit LCD driver and a PS/2 Keyboard driver.

It took perhaps 30 minutes to write a short c program to read the PS/2 keyboard; decode the scan code, write the code to the LCD and to set the ASCII bits on PORTD of my 16F877A PIC. I’ll be able to use PORTC to control the strobe, clear and reset bits for the Apple-1 very easily.

This got me to thinking; there are a number of small readily available programs for the Apple-1, most exist as a HEX file (Apple BASIC Example here) you type in and/or as a cassette tape you load. I can store these either in a serial FLASH or perhaps even in the FLASH within the PIC, a bit of coding and the function keys of a PS/2 keyboard will clear/reset the Apple-1, then send the key strokes to enter and run the program. For Basic programs it could even load up BASIC, run it, then enter the BASIC program.

Of course this project creates a PS/2 to Parallel ASCII keyboard encoder in the process, there are several already on the web, I simply wanted to create on myself.

Another fun project to add to my project list.

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