Episode 34 - 8080 VS Z80

[@jondhuse1549]

I was working at Intel when Shima-san returned to open the design center in Japan. He visited the US site where I was working to get a view into our design methodology and I was fortunate to be able spend some significant time with. He was a very thoughtful guy and it wasn't until later that I learned about what he had done earlier in his career. I would have been totally intimidated if I had known that!

[@johnpenner5182]

informative episode with interesting details. the Z80 was my first processor - in the TRS-80 model I, where a 14 year old kid in the 80's - was a revolution! you had to know Z80 assembly language in order to NOP around the floppy copy protection code, and enter a new jump point in hexdecimal to get the game to run - after you use TASMON to write out the memeory block of unencrypted code from RAM to disk as a binary file, and the new JMP point for start of code execution - yay! we can play meteor mission II and seadragon!! we had to listen to 450baud cassette loading from my pa's ghetto blaster to save onto cassette - because only rich kids could afford floppy drives. well - i found an old floppy drive for $45 which was damaged (it could read, but not write head was damaged). i had to etch a circiut board and build a +5 +12 Volt power supply, and work at the gas station to afford an expansion interface - but then - LDOS!! floppy drive 5.25" and 1200 baud modems!! oh my lord. i got grounded for playing a phoenix clone called 'demon seed' - those were the days! 👾 thanks for putting it all together. 🙏

[@riccardosven]

This small channel is a gem! You deserve way more subs!

[@BertGrink]

Great Video! Lots of little details i hadn't heard before, Bravo! Subbed as well.

[@youreale]

I love computer history and your channel is just amazing! thanks!

[@joefish6091]

Byte, Interface, PCW, their magazine 'repositories' (A word illegal on utube) are out there at legal places. Its very interesting to read the computer magazines from the 70s. 70s and 80s were worlds aprt, 70s and today more so. Our 8 16 32 core PCs of today are at least six magnitudes more powerful than the 1Mhz machines of the 70s. Solitaire Mines anybody !?

[@OfficialRainsynth]

My friend, you have earned a new subscriber. Keep up the great and informative work.

[@scharkalvin]

Well we had mainframe computers (IBM 360-370 family), Mini computers (PDP-8, PDP-11), and then the next step was Micro computers. In the beginning, it was about word size, 36-24 bit, 18-16 bit, then 8 bit. The latter expanded upwards over time.

[@adg1355]

AFAIR, there were variations of 360/370 on 8-bit underlying HW. I might be wrong though.

[@shaneveness5611]

Very interesting history, thanks!

[@william2william]

At the time micro computers came onto the market (1970s) there were already mini computers (the size of small refrigerators) so the next logical name for these smaller computers was micro computer. The Personal Computer moniker didn't happen until IBM came out with a micro computer called IBM PC 5150 and it was the introduction of IBM PC Clones that gave this type of computer (Intel x86 running DOS or Windows) its name, latter the name was shorted to PC Clones and shorted again to just PC.

[@CallousCoder]

The information is great, but it can do with some visuals and B-roll. I am looking on the same slide for 45 minutes...

[@semibiotic]

Yeah, lack of visuals is a great omission for this video audio.

[@tonybean9189]

I built my first computer on an Ithaca inter-systems s100 bus using a xylog z80 and a CPM version 1. I learned assembly and machine language on that box. Later on I took the dialogue and designed my own system and rode my own OS using machine language code. It was a wonderful experience back in the 1970s that I will never forget and I will always remember as I log as a really great company building really good components

[@VV-wl8gb]

Great stuff! Subbed :) I just bought a Cambridge Z88 featuring a Z80 and wanted to know more about the chip

[@perplexedmoth]

Nice channel. Would you consider to cover the Forth language and Forth CPUs?

[@adventofcomputing4504]

Definitely, I should throw that on my list.

[@TheSulross]

love getting the blow-by-blow of micro computing history of the 70s - most KZbin channels give a Cliff Notes version of the decade

[@AjinkyaMahajan]

It was an awesome explanation✨✨✌ Thanks

[@ian_b]

"Faggin" is pronounced with a soft "G", like Fa-gene.

[@gnamp]

This is one of those "it's pronounced Co-burn!" jobbies, isn't it?

[@G7VFY]

Not hard to see why the $25 6502 was so successful.

[@jorgeandrade20]

Z80s were also used in Musical Instruments (Electronic Organs, keyboards), Graphing calculators (TI-83, TI-84, TI-89) and the 8-bit computer platform MSX among others!

[@massimoa8954]

Very nice video! It brings back great memories of my first computer the Sharp MZ700. I loved the little 4 colour plotter. I studied the z80 assembler for months but in the end all my friends at school had the Commodore 64 and I had nobody to talk to. I wonder if one can run a z80 emulator on the mac ;-)

[@srfurley]

The Z80 was the first processor that I learned to program; I later moved on to 8086.

[@wintercoder6687]

Similar path... Z80 -> 6502 -> 8086 -> 80386 -> Heavy mix of C/Win32/Assembly. After that, most of my projects were on Pen based devices on ARM, so most was C/C++. I still have fond memories of (and actual code listings of) my Z80 code from the mid/late 70s.

[@ntal5859]

Are you sure it was the 8086 and not the 8088 as almost everyone had used the 8088 for the cheap 8 bit bus for ram (still 16 bit internal on the cpu) remember all the XT machines were 8088 which is an 8086 but like I said 8 bit external bus(mutilplexed).

[@srfurley]

@@ntal5859 No, we had no 8088 machines. We had a few 8086 ones, I can’t remember the model now, but most of our early 16 bit machines were Research Machines Nimbus, which had the little-used 80186 processor, which was a slightly upgraded 8086. I don’t know of any other desktop machines which used this processor, but they were later used as embedded controllers in some specialised equipment. These machines were not IBM compatible, but with a software emulator could run some IBM software. The hardware was quite different, but they did run MS-DOS. Servers were 286 or 386 based, and I remember getting our first 386 workstation, complete with 387 co-processor, to run Autodesk Generic CAD. This was a Micro Channel Machine, similar to the IBM ps/2.

[@Conenion]

Zilog even had a Z80000. A true 32-bit design released in 1986. But by then Intel's 386, which feature-wise is similar, had already taken most of the market share.

[@ArneChristianRosenfeldt]

In they year ARM and MIPS came to market. So if I would jump onto an incompatible ISA, that would have been it.

[@shaneveness5611]

Just to let you know, 8080 and 8085 have 8 lower address bits multiplexed with databus👌

[@PebblesChan]

And also does the 8088 and 16 bits for the 8086!

[@uni-byte]

Yes for the 8085, no for the 8080. The 8080 had full separate address and data pins.

[@kattphloxworthych]

When I was younger, I got my hands dirty on an Apple II with two processors, its onboard 6502 and another in slot 4, a Microsoft SoftCard which sported the topic of this video, the Z80. After putzing around with 8080 opcodes, I ultimately would get my hands on Microsoft's assembler, albeit for the Apple II's CP/M at the time. It not only had 8080 and Z80 opcodes, but the 6502's as well, being an Apple II product. When I started doing serious work with assembly, especially when I started working with Z80 opcides, I fell in love with the Z80 mnemonics. Intel's was extremely non-intuitive, and Zilog's were so refreshingly well-thought-out. Not only did they have additional addressing modes that the 8080 didn't have, they also consolidated the two instructions that get used the most for moving data, MOV and LDA. If I ever have to disassemble 8080 code, you can bet I'll output Zilog instructions because at the end of the day, nine times out of ten, if you have an actual eight-bit microprocessor in that class in something, you'll have a Z80-type processor, whether it's NEC's uPD780, the Hitachi HD64180 or, hell, even an actual Z80 or any of its derivatives. I -LOVED- that thing which is why you see Zilog's 70s logo as a hairclip on my VTuber model!

[@jorgeandrade20]

Sadly they just announced on April 15, 2024 that they're discontinuing production of the Z80 and the last day to place orders for a new Z80 is June 14, 2024. RIP Z-80, you've done all of us well in 48 years!!!

[@Hchris101]

Oh yeah 😎 that’s the stuff

[@johnrickard8512]

The Z80 also gets a mention from the Graphing Calculator world

[@MrKeplerton]

Interesting material, but you really need to configure that noisegate. It's way too agressive :)

[@G7VFY]

8008 was not a one chip system as the support chips are pretty much essential. The 8080 was an improvement but an incremental improvement, and the high cost and multiple supply rails were a pain and added to PSU complexity.

[@ArneChristianRosenfeldt]

Pretty essential is not essential. 8008 has a stack on die and IO ports also. Which other 8bit CPU has this? C64 and ZXSpectrum have multiple supply rails despite a CPU which only needs two. The extra supply rails are only used to provide bias to a diode. Almost no current flows. C64 has extra voltage stabilization for its DAC. So the bad design is when you already have a stabilizer in the external PSU. Then you don’t have enough voltage left to drive a stabilizer on the main board. CRTs need 5 different voltages. They easily get them all from one flyback transformer. Since the third rail connects to the bulk, there is no problem with more traces on the die. Single metal layer is still okay for two rails and clock .

[@G7VFY]

@@ArneChristianRosenfeldt The CPU's on C64, VIC-20 and ZX Spectrum run on 5v. The 8085 was also 5v only, but too little and too late. Also the additional rails like 12V added to the heat dries up caps and excessive heat can kill the chips.

[@ArneChristianRosenfeldt]

@@G7VFY their CPU runs on 12 V, but not the rest of the PCBs. You also may have seen PC PSUs. They always had +12V and -5 or even -12 for RS 232 . Like a PC uses buck converters , while home computers had to upconvert voltage. And why would you use electrolytes for low power bias voltage? Especially, if use a buck or boost converter? Or this charge pump

[@looneyburgmusic]

Don't think it's accurate to say the Z80 "blew Intel out of the water", since the Z80 was intentionally designed as a "better 8080 THAN the 8080". That story, of "CPU released by company "A", better CPU then released by company "B"" sort of became the default for the CPU industry from the 70's - today. No matter how great a processor might be, it's obsolete the moment it's unveiled, as every other processor designer instantly begins work on topping it.

[@kd1s]

Funny story building alarms. Lots of them use Z80 CPU's.

[@irgski]

Intel must not have had NDA’s for the engineers that left for Zilog….a definite competitor.

[@ArneChristianRosenfeldt]

They did not disclose anything. They founded their own company.

[@doughale1555]

you should really be comparing the 8085 to the Z80.

[@uni-byte]

Great information, but your visuals leave a bit to be desired. KZbin is a video platform. Provide some different pictures that go along with the dialog. A single image does not compel, especially for the core customer around here.

[@mike94560]

I just bought a Zilog Z-80 for $8.25 US on Apr 2022.

[@DerHeimatlose1]

Well I would call the MP944 the first microprocessor ever produced

[@randywatson8347]

I now know the Z80 and have respect.

[@Psychlist1972]

"In 1974 Intel released the 8080 processor, a chip long in the making. It was the first microprocessor that had the right combination of power and price to make personal computers viable" That statement is somewhat true, but not absolutely so. What about the contemporary Motorola 6800 and the processors that it spawned (including the MOS 6502 in 1975, based on the lawsuit-targeted 6501 from the year earlier). This lineage fueled a lot of the home computer boom including Apple, Commodore, CP/M systems, and eventually led to Acorn and then Arm, which is super important today.

[@hintoninstruments2369]

MPUs that are limited to 256 byte paging aren't the right combination. CP/M was written for the 8080 instruction set and so also ran on a Z80.

[@Psychlist1972]

@@hintoninstruments2369 But the popular personal computers from that time period were not CP/M, in general. Apple, Commodore, most of the things in the UK, the kit computers based on Motorola, etc. I'm nitpicking, but it's easy for folks to look at one single lineage and assume that was the most influential, and then miss what led up to what is the most common CPU architecture in the world today.

[@ArneChristianRosenfeldt]

Still looks like Intels move allowed engineers at Motorola to persuade management to integrate their discrete processor. Motorola already made very simplistic processors. Hence the 6800 has less registers.

[@ducksonplays4190]

The 8008 is actually the 3rd ya can't forget the 4040

[@uni-byte]

The 4040 came put about 18 months after the 8008.

[@ducksonplays4190]

@@uni-byte hmmm I don't know maybe it did I forgot to look at the 4040s release date but I don't think he mentioned the 4040

[@tomcombe4813]

The nobody is really designing the z80 into modern electronics. Even embedded systems. The only reason it's still in production is to maintain legacy hardware. Hardware built in the 70s and 80s that's still running today and nobody feels the need to update. They only ever update them when the manufacturer stops producing the chips, and because zilog are still producing the z80, they can just whack a new one when it breaks.

[@hintoninstruments2369]

Actually Z80s are still being used, but often as IP cores in FPGAs. There is also the Z180. Single chip microcontrollers still have naff UARTs and nothing has anything to compete with the Z80-SIO or Z8530 or the interrupt structure to support serious use. There is also the issue of redeveloping proven code when you have 40 years of it that would take years to rewrite and debug on anything else.

[@ArneChristianRosenfeldt]

@@hintoninstruments2369atmel AVR and similar is used

[@adg1355]

Z80 was released at the same time with 8086. That's the difference b/w 2 chip manufacturers - while innovators push the limits, epigons have to go for crums from the grown-ups' table.

[@herrbonk3635]

The 8086 design started in mid 1976, at almost exactly the same time the Z80 was released. 8086 designer Steven Morse copied many ideas from the Z80, and generalized some of them to try to kill off the Z80. Hence all the similarities. The 8086 was intented as just a temporary product, waiting for Intels ambitious but heavily delayed iAPX 432 processor (that started in 1975 but didn't get fully operational until 1982). A year into the design process, the goal with the 8086 (and 8087) was extended to not only try to fight off the Z80, but also the less delayed 16/32 bit processors from Zilog (Z8000), National (32016) and Motorola (68000), that were on their way.

[@hstrinzel]

Italian pronunciation: [fedeˈriːko fadˈdʒin], Venetian: [faˈdʒiŋ]; GREAT report otherwise.