They used a 2 MHz 8080 to produce a software UART function, without a timer, without an interrupt, and on a system that required you use a front-panel to enter the code.

Having it able to transmit, receive and load stuff from the TTY was a REAL boon!

I do remember the 10 CPS and, if 100 baud satidfies you a SW UART is very possible, you get the 5ms slack I referred to in the keypad response.

I still, occasionally dream of a tock, tock, tock with a 10Hz frequency. I'll never forget the sound and the 3 hours assemble time PER PASS of 2 passes. I recall the paper tape tearing after 5 hours of watching because needing to leave the darn thing for the duration of a pee break and all kinds of other 'joy' from those days.

Every time you, Richard, go back to the dark ages of external ROM, I think back to the TTY days and a logical extension of your proposals would be that the beginner should buy a surplus teletype. Why just go back to the dark ages, why not all the way to the stone age.

Erik