1. Home
  2. Embedded Programming
  3. W65C02S, Z80, 80C31 or other legacy processor?
  4. Page 2

W65C02S, Z80, 80C31 or other legacy processor?

The Z80 was a LOT easier to wire up, though. The 8080 _required_ two clocks, same rate just phased differently, and had a special clock generator chip sold with it for that purpose (8224, I think?) There was also a bus/system controller thing, too, that latched and decoded a status value and provided 'normal' bus signals. The 8085A was a huge improvement, including the clock generator inside, if I remember. And with the Z80, even an idiot could wire it up and make work. One supply voltage, no phase crap to deal with, no special bus controller, just simplicity itself.

I've no idea how hard it might be to actually find 8080 stuff, now. I have a few parts in a box -- enough to make one or two machines -- but they are rare birds, I think.

Jon

Reply to
Jon Kirwan
Loading thread data ...

  1. The 8080 is not static.
  2. The 8080 is not a complete processor. It needs 8224 and 8228.
  3. The complete static 8080-like processor is 8085. The Z80 has many subtle differences.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

formatting link

Reply to
Vladimir Vassilevsky

Amazing. The 8080 systems I built, starting back in 73 or 74, didn't use any 8224 nor 8228 chips. They worked. They ran embedded systems, also CP/M, quite accurately and satisfactorily. They also didn't use the S100 bus system. And I could halt the systems at or before any particular instruction execution, which seems quite static to me.

The only Z80 difference that counts has to do with the parity/overflow flag. Other differences have to do with resolution of undefined 8080 op-codes.

This is NOT a recommendation for new designs.

--
 [mail]: Chuck F (cbfalconer at maineline dot net) 
 [page]: 
            Try the download section.
Reply to
CBFalconer

..

Who are the target users ? In which operational areas, are they going to spend their time ?

PLCC44 89C51's are plug-able, and most still have an EA Pin, so can switch to run on external memory. [viz BASIC in FLASH, and LED.Demo Pgms in XRAM ]

What you ALSO want to try and 'catch' is pluggable AND SiliconDebug - SiliconDebug allows much smarter PC access, and you really want to be ahead of the 20yo 'download and hope' spartan systems.

A nice candidate here would be the AT89C51RE2, PLCC44 and OCD, and Static. Perhaps with FRAM ? FM1808 has the Address latch built in, and can mix Data and Code ?

Also plenty of 8051BASIC's out there...

Watching activity LEDs ? - How much will this be used ? Pin-Leds are likely to be of limited use.

Nicer here might be a Dot-Matrix LED display (8x8?), that is Address- region coded. Trainees can then see single step, and RUN code operation. A 44 pin PLCC CPLD [ATF1504?} would handle Address to Display mapping. You could show OpCode.WR.RD datas on 3 rows, and leave 5 (40 leds) as address-area mappings.

Shifting to plugable modules (SMD uCon DIP PCBs) opens more devices .... eg SiLabs ones have good USB ToolStick debug support.

-jg

Reply to
-jg

Selected, highly-motivated first-world kids in the general vicinity of middle school age. It is to be assumed that they do not have another computer. The nature of the project is such that using a modern chip natively is preferable to using a vintage chip in emulation,

Download and hope, or rather type in and hope, is precisely the desired goal!

For 6502 I was thinking of Tiny BASIC, which has been ported to C.

Probably quite a lot.

Reply to
zwsdotcom

Those are both getting pretty long in the tooth. Hard to pick between them- I see very little 6502, but would much rather work with it, whereas I think the Z80 as a microprocessor got wider penetration so it will probably be around a bit longer.

I do like the suggestion of the 68000-- it's relatively pleasant to work with too.

If cost is not very important, I guess you could stick a BGA or QFP FPGA onto a 40 pin header and make it do whatever you like.

Keep in mind that current production 8051-style microcontrollers (eg. AT89S52) can be told to ignore the internal flash and go external with their data/address bus by pulling the /EA line down. The low address and data are muxed, so you need a latch too. They're quite cheap (

Reply to
Spehro Pefhany

I've an original manual for BASIC-52, ordered when Intel was still printing them and still gave them away to anyone asking. I suspect that the manual can be found in PDF form on the web. I also have a copy of it in ASCII text form, but not PDF.

I have collected some incarnations of BASIC-52 in ZIP file form -- the late 1986 versions for v1.1 divide the code into two files, the BASIC and FP written in assembly, but one of them at least just provides a single source file (as modified by D. Wulf in late 1999.) I also picked up I2C support modifications and I suspect there are other versions floating about that support other peripherals, too.

Which makes me wonder about the licensing of BASIC-52 for commercial use. I just have no idea except that I haven't ever worried about using it for hobbyist purposes.

...

Lewin mentioned Tiny BASIC, which had its development documented in Dr. Dobb's Journal of Tiny BASIC Calisthenics and Orthodontia. It used yet another intermediate interpreter to interpret BASIC and as Lewin has already mentioned someone has ported it to c, which I take to mean that the intermediate language interpreter has been re-written in c and may then be used to interpret the interpreter's small bit of code. It packs down small, but it is pretty slow running code. In any case, with the IL in c the whole thing can be set up on most anything out there with only necessary modifications to the c code, which shouldn't be too hard to do. So maybe Lewin's right to consider Tiny BASIC.

Jon

Reply to
Jon Kirwan

Oh - So this has to do everything ? Screen / Keyboard / Line Editor ? What screen then ? Volumes seem small for that target ?

TurboPASCAL 1.0 perhaps ? I have wondered what would happen if Zilog did a eZ80+TP1.0 bundle...

How Complex a Pgm do you expect from them ?

How will they save their work ?

But if this is running a basic engine, 'single step' led watching is not really going to make much sense to someone watching ?

Memory Map decode to LEDs could be more useful, or if you chose TV- out, maybe a display area could show code-area.

-jg

Reply to
-jg

Thinking some more on this, how they USE this is going to be very important, and it needs dragging into this millennium :)

So, whilst they may work stand-alone, you can expect access to a PC somewhere.

That makes USB a natural. (also taps into USB plugpacks, the new cellphone std)

formatting link

36_3_7.html

Says " The AT83C5134, AT83C5135 and AT83C5136 are available now in 32- pin QFN packages. Pricing starts at US$1.30, US$1.40 and US$1.55 for

10k units. The AT83C5136 is also available in a 28-pin SOIC package, 48-pin QFN package and a 64-pin VQFP package."

with 32K ROM, and 32KEE, it can be a tiny flash drive, and the ROM contains the Editor + Basic. Right price.

Whilst it may all fit into one device, I'd start with two: Target one as TV.Kbd.Editor and one as USB.basic - The TV one can run heavily loaded for the TV Scan. 32K EE would nicely cover language variants. Two cores should also give you some nice debug power.

-jg

Reply to
-jg

They have a minimum clock frequency (0.5MHz), and are thus not static.

formatting link

Best regards, Spehro Pefhany

--
"it's the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Reply to
Spehro Pefhany

Maybe not quiete the answer, but we did such with the Infineon parts

80C167 at school, though we had to design it from the scratch and programming was a minor goal (tgough we had to prove it works).

Ah, you want to avoid learning yourself ? :-)

But speaking of 6502, I'd recommend Opencores and an CPLD.

--
42Bastian
Do not email to bastian42@yahoo.com, it's a spam-only account :-)
Use @monlynx.de instead !
Reply to
42Bastian Schick

A small while ago, I found out to my delight that you can indeed still purchase 1802's. Even the price is probably about the same as it was back in the 1980's, you can get one for about hundred bucks.

--
Pertti
Reply to
Pertti Kellomaki

Ditto. The two phase 12V clock can be generated and the status signals can be latched by some other means, however it doesn't make 8080 a complete processor.

The clock can't be stopped; there was the low limit on the clock frequency. This is not static.

FWIW the original Z80 wasn't static either; it had the limit on the max. duration of the clock pulse. Although there used to be 100% static CMOS clones of Z80.

Yea. Design with tubes and relays.

Vladimir Vassilevsky DSP and Mixed Signal Design Consultant

formatting link

Reply to
Vladimir Vassilevsky

Worse -- it had a pointer to the register that happened to be the program counter at the time. There were several methods for implementing a function call, mostly involving switching around the program counter register pointer.

I used to tell people it was a "NHISC" processor -- "Never Had an Instruction Set Computer".

--
http://www.wescottdesign.com
Reply to
Tim Wescott

Emulate it on a CPLD?

But yea, it's not exactly available now.

--
http://www.wescottdesign.com
Reply to
Tim Wescott

Definitely not; it was designed explicitly to help them understand the previous millennium :)

By definition, this hardware platform will only be offered to students who do not have a PC. There is also a pure-software simulator that will be used by those more fortunate students. I don't think I'll be writing the simulator, it's not part of the contract (yet).

Significant numbers of American children do not have a home PC. Many, if not most, American schoolrooms do not have one PC per child. Therefore the purpose of the hardware platform is to meet the specific paedagogical goals of the associated teaching program, in situations where the students do not have one PC per child. Funding for the programs this is designed to support is very limited. The cost goal is to equip a 30-student block with all required materials for

Reply to
zwsdotcom

Is it the regular consumer version or the aerospace version? I strongly suspect that any regular consumer version parts you find on the market today are NOS or even pulls from old equipment.

For $100 you can buy a complete short-form kit including the 1802 CPU

Reply to
zwsdotcom

It is the aerospace version:

Prices seem to be going up. I stumbled onto the page last summer and the price tag was about $90, now it is up to $107. Time to stock up I guess ;-)

That looks tempting indeed.

--
Pertti
Reply to
Pertti Kellomaki

You missed the key word 'access'.

I can understand this needs to run stand-alone - but it also should PC-connect easily, so they can

  • Upload homework to the teachers PC
  • Go to a mates/cousins house, and access a PC
  • sneak some time on any nearby PC
  • Want to Keep using it, when they DO get a PC

You have not mentioned Display and keyboard pathways ?

-jg

Reply to
-jg

... snip ...

Don't even think of any Turbo Pascal. You can get a full ISO validated Pascal system. Unfortunately the compiler and assembler sources have been lost, but the binaries and manuals are all there. It was in use for almost 15 years generating mainly medical embedded systems, but this is for CP/M. See:

(It will work especially nicely when combined with DOSPLUS 2.5).

--
 [mail]: Chuck F (cbfalconer at maineline dot net) 
 [page]: 
            Try the download section.
Reply to
CBFalconer

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.