Found a great kit using the Z80 and built it and spent many nights with a logic probe and oscilloscope learning digital eletronics. Also devoured the Z80 manual learning the instruction set.

I'm nearly 70 now but remember those days like they were yesterday.

Truly a magnificent CPU

It wasn't in regards to the flag register. The parity flag behaved differently for some ops.

And of course it would be possible to write an 8080 program that used undefined ops that would execute in some random way (often just duplicating an existing instruction) while the Z80 repurposed that opcode for something new.

I wrote a quick post a while back about my Z-80 experiences here:

https://jimlawless.net/blog/posts/z-80/

https://spectrumcomputing.co.uk/entry/2000237/Book/Mastering...

http://www.primrosebank.net/computers/zxspectrum/docs/Comple...

I was just thinking of you the other day in fact! Do you remember that terrible flight simulator we wrote in your BASIC, then discovering your assembly!!!! Yes, I remember, at 10 I was incapable of ASM, but that's why they made the 6502C years later!!!!! I still love you Z80, you did pop my cherry! <3

I hope ur not still upset about that whole AIM-65 incident.....

It has the usual opcodes and directives, includes, relocation data etc, with a couple of other helpful output files alongside the expected binary one.

Because the driver for it was coding on the ZX Spectrum it will also create tap files with a BASIC loader and loading screen support. And it has a not very featuresome sprite editor built in for the Spectrum screen and attributes. Oh, and a PNG-to-SCR conversion process for loading screens that does a bit of work to show problem areas (as heatmaps).

It's only actually been used by myself and one other person so there may be a few hiccups, but it WOMM :)

[1] https://github.com/kcartlidge/GoZ80

One three-day weekend, I slept about 4 hours while I was disassembling the BASIC ROM to find nuggets I could call in my Z80 programs, and also to learn so much more about the video, the cassette interface, interrupts, etc. My notebook looked like something a madman had scribbled on the walls of an asylum to everyone around me, but to me it was perfectly organized, and I used it to reference things I would use later in my programs. I got to the point where I could read the hex dumps and "see" the op codes in my mind; people would look over my shoulder while I was debugging, and I'd be explaining what the code was doing, but I hadn't disassembled it yet. I didn't even realize I was doing that until one of my classmates pointed it out: "Hey, disassemble that. I'm not following you, how the heck do you see that?"

And all of this because my science teacher had that TRS-80 Model I sitting in the corner of his classroom gathering dust; nobody knew what it was, I didn't either, but I had to figure it out. I've always had this bug, I don't believe in magic, I want to know how everything works, it's been an insatiable thing all my life, that first machine set me on a course of learning for the rest of my life.

Thanks, Mr. Kruzan, you changed my life. I'll never forget you. Oh, and thanks to all the people who created the Z80, the TRS-80 Model I, and paved the path for me to learn computers and never stop learning.

We are truly building on the shoulders of giants; every generation, more giants. It's humbling to look back and think about it forty-five years later...

[1] https://www.trs-80.org/edtasm.html

[2] http://www.z80.info/zip/zaks_book.pdf

PS: Pretty sure the memcpy examples have a stack bug.

Unlike anything I had ever experienced, it was life changing, I would bike to the store every day after school

Family couldn't afford the computer but I bought all the books and would read them at home over and over and gawk at all the accessories in the catalogs

Then family surprised me with it as a birthday present with all the relatives paying for it, pretty sure I was the only person in town with one, even the school didn't get one for years

Didn't have any way to save programs, not even the cassette recorder which was too expensive, had to memorize them and retype every time I turned it on

There was an active modding scene around them, and even some attempts at creating a replacement firmware, but unfortunately most of that seems to have disappeared.

Cheers to Rodnay Zaks for "Programming the Z80"!

[0] https://github.com/siraben/zkeme80

As a kid, it was all about 6502 micros, but my early professional love was Z80 and it still warms my heart to think about. Sure, the “other” 8 bit CPUs had zero page, but block instructions and 16 bit extensions FTW. <3

First, my Father wanted to try to add some peripherals to the original TRS-80 Model 1. So, what he was interested in doing was asserting the BUSREQ pin to tell the Z80 to get ready so that he could have the bus, ideally waiting for the BUSACK signal to know when it was his.

Unfortunately, on the Model 1, when you assert the BUSREQ pin, it is tied directly to the tri-state buffers that handle the address and data bus. So, as soon as you make the request, the Z80 loses all access to its memory and data -- mid cycle. Which, you know, can be Bad. Radio Shack labels this pin TEST and uses it for internal testing. But it was definitely a bit of a disappointment to my Fathers efforts.

The second one is when I learned that the Game Boy Advance has a Z80 built into its chip. The designers drag and dropped a Z80 core (tweaked for GB) just so they could run legacy GB games on it. It just kind of bends your view of the computing world when something as significant as a Z80 can just be shoved into the corner of a die for "just in case" functionality.

Just shows how far we had come at the time.

I'm aware of: proprietary ones like GEN80 (my fav way back), M80/L80, at least one open source assembler written in plain C, and probably some table-driven assemblers targeting multiple architectures.

However, you had to be a programmer Anno Dominii 1975 to fully understand what heavenly Joy and Jubilation Z80 was.