What's so special about Z80?
John A. Zoidberg
Posts: 514
I may be too young to know about this, but had that Z80 actually changed the whole world, alongside with the 6502?
I checked the 'net for the history and even the website itself. Yes, they were very famous. Even Gameboys used that. Or the other cheap toys and remote controls in your home.
What had made it stood against the other brands? Bill Mensch's 6502 is everywhere, and could be secretly hiding in one of our household stuff, or the everyday stuff we find in Tesco.
Once I almost bought a Z80 training board, but didn't so because I had an Introductory CAD class and had to skip that Z80 briefing in another lab.
I checked the 'net for the history and even the website itself. Yes, they were very famous. Even Gameboys used that. Or the other cheap toys and remote controls in your home.
What had made it stood against the other brands? Bill Mensch's 6502 is everywhere, and could be secretly hiding in one of our household stuff, or the everyday stuff we find in Tesco.
Once I almost bought a Z80 training board, but didn't so because I had an Introductory CAD class and had to skip that Z80 briefing in another lab.
Comments
I learnt to program in Basic on a TRS-80 Model 1 and also to program in Assembly Language.
It was a great CPU.
I had a TRS-80 Model II. It was a good machine, one of the best things Radio Shack ever made. And I use to rebuild Hewlett-Packard workstations for resale and they very covertly had Z-80 microprocessors at their very hearts. It was one of the several very good 8 bit processors of that stage in microcomputer development - the Z-80, the 8080, the 6502. You had to commit to one of them to begin to learn anything.
I believe that Parallax's wizard, Chip Gracy started on a Z-80 with a Timex Sinclair. Every romance starts with a first kiss; every programmer starts with a first computer.
There were others; I had a machine that flopped and was surplused, with an 8080A onboard. The COSMAC kits used the 1802, which also found a lot of use in space probes because RCA came out with a radiation hardened version. (It was also a very weird chip, almost propellerish in its minimalist quirkiness.) When Intel came out with the 8088 and 8086, they were expensive, slow, code-bloaty, and hard to use. IBM chose the 8088 for the IBM PC though so that it wouldn't be using the same CPU as either Tandy or Apple, and since the chip was very forward looking in its architecture the rest, as they say, is history.
I used to like the Nat Semi SC/MP, which came out at about the same time. It was a low-end device, but had the nice feature of a shift register, that made implementing a software UART quite trivial.
Then there were the TI 999x 16-bit parts, which were used in a quite popular range of home computers. I was involved with a parallel processing system that used three 9995 devices, with a Z80 for I/O. We needed to do a relatively simple calculation as fast as possible for three axes of an electro-optical system for measuring the position of objects up to 10m away. The 9995 was the fastest thing available then for doing integer arithmetic involving multiplication and division. We couldn't afford the TI development system, so I wrote a cross-assembler for it running on my TRS-80 Model I, using macros in Microsoft's Macro-80 assembler. The TRS-80 was also used for programming the EPROMs.
I see.
Unfortunately in SE Asia, I don't see very old computers there like what you have mentioned. Probably those computers belong in the universities or offices at that time. The only oldest computer I saw was the ones with the CPU with the power switch at the sides instead of being front. In a flea market in a shopping center 25kms away from me, once, they sold a 286 computer. At old times, computers were very very expensive and all people could afford is the NES and a 386SX during the early 90s.
That Z80 and 6502s are so famous, even it has Russian and/or (maybe) Chinese clones.
The computing world in Taiwan during the 80s is more different than the ones in SE Asia, I would guess, due to the more advanced technology they have, and more educated manpower.
Not sure about SE Asia or China but Russia and E Germany had S100 clones and what looked to be an Apple clone when I was there in the early 80's.
Not sure if they used clone 8080/Z80 chips in them, but they did clone 8080, Z80, and 8088 at some point.
For me, the Z-80 was the heart of my very first computer: the Timex-Sinclair TS-1000. Which may also help explain its popularity. Also, I was fooling around with some Z-80 ASM code at my first tech job. An engineer saw it, and asked if I knew what I was doing. When I replied, "Yes," he grabbed me to work with the 8085 controller.
Some of the advantages of the Z-80 over the 8085 (which was a single-supply 8080 with a few more features) was that the Z-80 could automatically refresh dynamic RAM; it had secondary 8/16 bit registers and a secondary accumulator & flag register pair -- good for servicing interrupts; two 16-bit index registers, and bit set, reset, and test commands.
Finally, as someone mentioned, it has a "Z" in the name!
--Rich
Speaking of the "Scamp," I believe I have a couple of them, disguised as the NS8073 -- with a BASIC interpreter burned into the chip. The boards are S-L-O-W -- they can not even generate a 1mS square wave -- but they are fun to play with every now and again. The BASIC program -- in ASCII -- is burned into the EPROM, and the micro reads it out and interprets it. I've replaced the EPROM with a battery-backed RAM, and chuckled as I used my R/S Model 100 to program the boards.
Ahhh, the good old days when you could get your head around a computer. <sniff!>
--Rich
The 16-bit TI chips had a large register file, of which only 16 registers were in use at any one time. That made interrupt handling very fast - one just switched to another set. By having them overlap, data could be accessed without having to move it in and out of memory. I think that the SPARC had something similar.
Although I spent a lot more time with my TRS-80s, I started with a Motorola D2 kit, with an MC6800:
http://www.computermuseumgroningen.nl/motorola/mek6800d2.html
It came as two PCBs and all the components, which had to be soldered in. It worked first time, to my surprise. It had two 128 byte SRAMs (that's bytes, not kbytes). One was used by the system giving the user a whole 128 bytes for programs. It had a socket for a second RAM chip, which I installed. Someone I knew built his up into a full-blown computer in a rack with a keyboard and VDU, lots of RAM and a floppy disk.
Forgive me, this post is redundant. I tried to delete, but for some reason I can't. Nonetheless, it is a bit of interesting history.
[The first computer I programmed was some IBM thing filling a room somewhere. My interface to it was a card punch machine and a hole in the wall where people accepted cards and handed out printouts.]
I liked Z80 assembly language. The TRS-80 saw a lot of hacking in one form or another - added chips to use the lower case fonts (you needed an extra bit per character), external keyboard (wired in parallel to the existing keyboard matrix), and countless devices connected directly to the Z80 bus (which was conveniently available outside the case). A number of the connected devices were interfaced to using assembly (usually small bits of code, nothing too big).
Like I said, I liked Z80 assembly and it seemed to make sense. 6809 wasn't too bad, either. I never really liked 6502 but I didn't do much with it (if I recall correctly you had to deal with paged memory).
Completely unrelated note: My first IBM compatible (replacing the TRS-80 Model I) was a Tandy 1000 (also from RS). That was replaced in 1986 by an IBM AT compatible from a company that had only been around for a year or two called PC's Limited. They have a different name now.
All this talk about retro computing, had me search the forum for a micro I never got to talk to, I was around seventeen when I bought the NS SC/MP Evauation Kit, I probably put it together the same day it came in the mail. It took me awhile to get a power supply together, and my original plan was to use a WWII Klienshmidt Teletype as a terminal, but instead opted to put together a popular TV Typewriter at the time. I had all the pieces put together but never got them conected each other, a new PC may have had my attention.
My question is, do I want to go with the old school binary in/out? or interface to a Propeller for terminal emulation? Because it's an old board, I thought it should be in a cabinet on it's own, a great trainer. On the other hand a hybrid would be more fun, and finish what I started forty year's ago.
Any ideas or inspiration would be appreciated.
_mike
Going back to John A. Zoidberg's question of 2011. Remember that before the IBM PC there was a lot of business going on using 8 bit CP/M machines. Mostly Z80 based. But only ever needed the power of the Intel 8080, which grew up to be the Intel core whatever you use today.
MikeDYur,
Not sure what you mean. If you have an SC/MP that can talk to a teletype why not just use a Prop as a VT100 terminal and talk to that instead?
But is it even a great trainer ?
Does it still work ?
Can you run the software needed ?
Might be best to just quietly put it back in its resting place, and use something that does have current software and tools, and that you can buy in 2015.
Maybe we can buy a similar thing in 2016!
I am not sure t it does work, I just had a need to revisit the past, and finish something I started, does this deserve a box of it's own, maybe to show people history?
Das blinken lights are retro cool looking. I looked that thing up, and it's got an 8 bit page of RAM, and runs MINBUG, which appears to be a monitor and debugger.
You can use a terminal, or go for Das Flippen Switches for the max retro, curio fun!
That's what I Was hoping to hear, after researching on internet, I think it should be some what true to a design I found, I question the power supply circuit, can the modern day small form factor power supply be better? Especially if I install a port, and use a prop for display.
I think it's a little piece of computer history, and not sure how many are still out there, I agree, switches and LEDs and some aluminum and wood, is what it deserves.
I remember seeing those in the Digi-Key catalog in the 80's, always wanted one but never got around to ordering one.
C.W.
My fealings too, Heater mentioned in another thread to watch out for the electrolytic's, I need to check them, I have kept this board as clean as possible over the years, but static might have bitten it.
_mike
And it's reverse.