This is the very beginning of my Enigma M4 simulator that I want to run on the Intel 4004. For anyone with experience programming the i4004, let me know what tricks or improvements I can add to do what I am doing in a better way.
The ONLY thing implemented at this time is the code that acquires a line from the terminal. The line is saved to data register memory and its length is kept in a register pair (E/F). It supports backspace, ctrl-z to backspace an entire line, only allows 78 characters, makes sure the character is in the range of $20-$7F, and converts lowercase to uppercase. This doesn't sound like a lot, but it has taken some work on a 4 bit CPU when characters are 8 bits!
There is no command processing and absolutely no Enigma cipher operation at this point. I suppose it is a race to see if I can fit all of that within 4K!
The HEX file is included if you want to try running it in my emulator posted in the other thread.
The ONLY thing implemented at this time is the code that acquires a line from the terminal. The line is saved to data register memory and its length is kept in a register pair (E/F). It supports backspace, ctrl-z to backspace an entire line, only allows 78 characters, makes sure the character is in the range of $20-$7F, and converts lowercase to uppercase. This doesn't sound like a lot, but it has taken some work on a 4 bit CPU when characters are 8 bits!
There is no command processing and absolutely no Enigma cipher operation at this point. I suppose it is a race to see if I can fit all of that within 4K!
The HEX file is included if you want to try running it in my emulator posted in the other thread.