This is the 6502 assembly code I wrote in the mid 80s on my Apple //e to extend the Applesoft BASIC with 20+ new commands to access the Apple Tell card.
Cristel allowed to write videotex servers using the Apple II BASIC using commands like:
- &WAIT : to wait for an incoming call
- &PRINT : to send some text on the (remote) Minitel screen
- &INPUT : to wait for a user input etc...
I retrieved this source code from my 35+ years old floppies using an Apple //c bought on ebay and the Floppy Emu SD (emulates a floppy drive and stores data on microSD card). Then I used AppleCommander on my Mac to extract the content on the source files.
I was using BIGMAC assembler from Glen Bredon, which then became "Merlin" see https://en.wikipedia.org/wiki/Merlin_(assembler)