Hello from 2021. Thanks for the great video. My CP/M assembly programming never went beyond a "Hello world" program so this is a welcome refresher course. I actually taught COBOL programming on CP/M machines (I think they were Logabax? using 8" disk drives) in the early 80s, which makes me a criminal as per E.W. Dijkstra 😃 With two 8" disk drives, compilation was relatively painless and fast. I don't recall that it required any disk swapping. I loved CP/M and its cryptic command names (ERA, PIP...). I had a chance to work later on its descendants CP/M-86 and the little known Concurrent CP/M-86, a real multitasking CP/M.

Back in High School electronics class, we built a HeathKit H89 in my senior year. I took that thing home on the weekends as often as I could. Never got down to assembly, but did a lot of BASIC programming. I'd been the lead on the build too, did most of the soldering. I miss those days. Then I open a couple of terminals to a server and an powermac running linux and don't miss them quite as much. Enjoying the videos Mike. Thanks.

I have wanted to know this information for years. So thankful you did this! Solves an ancient hole in my knowledge!

Thanks so much for making these videos. I searched on youtube and there's a lot of historical marketing-type stuff, but your intro/tutorials were really what I was hoping to find. Very well done!

Mike, Your videos are great. I must have read dozens of documents related to the Altair but nothing comes close to seeing it in action. What a great record of how to operate this machine for anyone who is interested or who owns one. Thanks.

Fantastic video! I just started playing with CP/M on my 8800micro today. I managed to figure things out by reading the CP/M documentation and by using DDT, but your video would have answered exactly the important questions that I encountered and wondered about as well!

In my early days i have written a new CCP for the Bondwell 12/14. I discovered that the eprom inside the bondwell occupies 4K memory space, but was wired for 16K size. Great idea:!!! Program a eprom with the most used com files and transfer these from the rom to ram. Lots of wire and solder later it works. Super fast rom disk. The bondwell is still here.....

It was a delight to watch!

CP/M. The good old days.

All day long, people will argue about which OS/Programming paradigm is better, but a TRUE Geek uses MANY. :D

I've never used CP/M, but my first experience coding Assembler was with DOS 3.3 or so, and it looks very similar to CP/M ASM, "ORG 100h" and all. DOS's origins in QDOS, which imitated CP/M is the reason, of course. In school, we had a contest to see who could write the smallest COM program that accomplishes a specific task. I won, with my 23-byte COM program. It was so long ago I don't remember what it did.

very nice just building my CPM system so ver helpful

'miserable' doesn't begin to describe ED. We are truly spoiled with modern dev environments.

Hello Mike That is all this comment does!

Learning, learning, learning ... but you might want to mention the keystrokes you were using in the WM editor ... maybe add those under the Intro...section.

Does the BIOS always reside in memory?

For sure helps me understand how the terminal environment works. LIKE LIKE LIKE

Why is the top of memory at 59k, though? That seems like a really weird amount. Is it that the system has 64kb RAM but there's also 5kb of ROM which requires additional cleverness to shadow out when not strictly needed?

Thanks, I knew there was an easier way to input strings!\

So everething lower than BDOS jumps is free to use? This is documented nowere

Your videos are awesome. How do you connect the Altair 8800 to monitor and keyboard, Are they special devices? Can you explain in detail in the separate video.

I would like to see the basic source code asm....

Nice video! I wonder why the CCP gives a so limited stack space instead of setting the SP just before the start of CCP (e.g. LD SP, 0BFFFH) -- EDIT: I now see why: if your program is large enough and uses the CCP ram space, then the stack would be overwritten. So it's actually a good choice.

But address zero is where the Z80 starts so jumping there is surely the equivalent of a cold reset

So whats inside of it? A Raspberry pi or something like it? :-)

Great video, but CCP = Console Command Processor

REAL programmers set the boot address with toggle switches and blinkenlights!

The story of DOS is basically a cliche betray story to CP/M Quite sad though

Hello Mike That is all this comment says!

You sound like a great friend of mine, but, no offense to him, he says he knows shit about Programming and Hardware... :D