The good old days of CP/M 2.2 on a TRS-80 with an 8-bit Z80 CPU

I was reading the news on the release of Windows 7 and stopped to think of the early days of my IT career and what an OS looked like then. I thought way back to one of the first microcomputer disk operating systems I ever used: CP/M. I actually remembered the few resident commands we had back then in CP/M: DIR, ERA, REN, TYPE, SAVE and USER. I remember that clearly because, back in the 1980s, I taught some classes on CP/M (while still attending college) and even wrote a little booklet (in Portuguese) on it.

That was back in Brazil and we used a clone of the TRS-80 Model III computer called CP 500 from Prologica, running on an 8-bit Z80 CPU at 2MHz, 48KB of RAM and a 5 1/4" floppy drive (holding less than 400KB of data). I first used the CP 500 at the school where I taught those classes and ended up owning one later on. Back then, we used applications like  Wordstar, SuperCalc and DBase II, and it all used to fit in a single floppy (leaving some free space for some documents).

It’s amazing how these days there are online references to pretty much anything you can remember. I found Wikipedia pages on:

For those that can read Portuguese, I also found:

To my amazement, I also found copies of old CP/M manuals dating back to 1976, including the CP/M 2.2 manual from 1983 at That trip down memory lane reminded me of the BASIC interpreters we used on those machines (both the resident basic for the TRS-80 and the MBASIC interpreter for CP/M). I also looked at some of my old archives on DVD and found some old MBASIC code I wrote for that computer.

I also stumbled upon a series of recent videos on the history of Microsoft at This includes an episode about the year 1977 when Microsoft released their the first Z80 BASIC interpreter and has Bill Gates talking about the launch of the TRS-80 computer:  That was also the year Elvis died and the first Star Wars movie was released.

Yeah… I guess I am getting old :-)