I have a couple but I'm working with the z80b. I have everything working with a manual clock along with a555 time clock running at 20 hz. Above that it is too fast to figure out what itit doing . The can oscillator i have is a 7.something. It will drive a baud generator on a serial interface, but I think it is too fast for the 6850. I have a z8470 dart too and ordered a few things last night. I might try timing a 555 timer to generate a baud need nothin more than 2400 or even 1200 at the moment. I'm not sure how exact the baud generator needs to be to work with a terminal.
With an NMOS Mostek Z80 (and with many others) with an oscilloscope confirm that the CPU Clock signal maximum is at least Vcc- 0.6V and below Vcc + 0.3V This is different to the standard Mostek NMOS Z80 signal levels of 2.0V.
It's stipulated on page III-72 of the Mostek Z80 Microcomputer Data book.
I'll check when I get home tonight. According to the packing slip it is mk3880bn-l .But I'll check the chip when I get home. I do have a CTC I might try tonight. I do have 1.8432mhz crystal oscillators coming tomorrow. Yes. I remember thoes protocols. Lol. Blast from the past. Lol. Anyway. I haven't had much time to work on it much this week,. I have been doing a lot of reading though on the various chips. Thanks.
What is the exact part number of the Z80 you're using? It'd be like Z84xxx or Z84Cxxx for the later revisions.
This determines the electrical characteristics.
Not essential but common baud rate generator crystal frequencies are multiples of 1.8432 MHz - this something that is easily divisible to get most or all of the common baud rates.
In the old days baud rate generator ICs (or Z80 CTC) would be used to divide this frequency down to the desired bit rate. (These days they're inbuilt into embedded micros).
With the above crystal a divisor of 6144 yields 300 baud, 192 yields 9600 baud.
A good project to do is to write an X,Y or ZMODEM program to download and upload files.
