use LPT port with RC-filter. For Micro$oft GWBASIC/BASIC we need hook int 15h, so small TSR program (with source code) can be found here: https://www.phantom.sannata.org/view...163351#p163351
LPT pin description: DATA_0 --> CAS_OUT, DATA_1 --> MOTOR_ON/OFF, ERROR --> CAS_IN.
For save BASIC program type: SAVE “CAS1:FILENAME”, for load: LOAD “CAS1:”