My Home Made Z80 Computers - Page 1
Forum section: electronics / projects

author: im_a_human
author_rank: Regular Contributor
timestamp: October 07, 2010, 03:49:22 pm
content: Hello! i have some home made projects to show everyone. Z80 computers! I have been a fan of Z80 based systems for along time now, 20 years in fact. These particular ones in my photos which i will show you in a bit are based on a very popular system that i believe is still available to buy at:-http://www.flite.co.uk/microprofessor-mpf-1b-z80-training-system.htmI first used these at Brooklands College in Weybridge, Surrey, in the UK 20 years ago!!! I liked them so much i decided to build my own. And here are my versions:-http://www.flickr.com/photos/32042005@N05/This is not all of them as i had made six systems in total. I sold three sometime ago which i wish i hadn't done now. Anyway what ive done is to build and customise the existing design onto veroboard andadd lots of extra features that would be really usefull that didnt come with the original. The original Microprofessor had a CPU clock speed of 1.79 Mhz and at most 10Kb of onboard ram. My Most recent build of this computer which ive made this year, i gave it a clock speed of 12Mhz! and 256KB of battery backed ram!Lots of the features of my systems are to do with making music and you can see they all have MIDI serial ports. The two larger ones also have 8 bit analogue to digital converters and 8 bit digital to analogue converters for sampling and playing back audio and also for audio signal processing.I have various bits of outboard gear to go with them as you can see in the photos, LCD displays and a retro LED matrix game board which i want to use to recreate John Conway's Game Of Life on.Also in my most recent build im making an analogue synthesizer controlled by the computer which will be incorporated to the system and allow me to play it with a MIDI keyboard.Well ive gotta fly for now but i will be back with more info on my projects so feel free to leave any comments or questios please.

author: bound
author_rank: Newbie
timestamp: October 07, 2010, 05:16:12 pm
content: Hi , have a look at this :http://www.retroleum.co.uk/category/progress-report/best z80 sbc ever !!

author: im_a_human
author_rank: Regular Contributor
timestamp: November 22, 2010, 02:03:13 pm
content: Hello again!Ive been working on my Z80 computer projects and i have made a simple implementation of Conway's game of life you can see here:

author: Ferroto
author_rank: Frequent Contributor
timestamp: November 22, 2010, 09:15:58 pm
content: Impressive. I dare you to try and get that past airport security

author: RayJones
author_rank: Frequent Contributor
timestamp: November 23, 2010, 07:36:15 am
content: LOL, reminds me of the time I was carrying an Agilent Noise Source past security.Never seen so much interest in a piece of test equipment by the hired goons.When I told them it cost several thousand dollars, they gave it back real quick in case they dropped itBut yeah, that game of life would never make it far I reckon.

author: saturation
author_rank: Super Contributor
timestamp: November 23, 2010, 12:05:15 pm
content: Nice job, clean and professional!Quote from: im_a_human on November 22, 2010, 02:03:13 pm

author: CryptLordGR
author_rank: Contributor
timestamp: November 23, 2010, 12:39:28 pm
content: Excellent work i hope i make such a machine in the future too.

author: gushh
author_rank: Newbie
timestamp: November 26, 2010, 07:11:13 pm
content: Quote from: Ferroto on November 22, 2010, 09:15:58 pmExactly my thought! -- You can't even have a few ICs in a bag without having them shove you inside a tiny dirty room and interrogate you!What has this world come to...As per the original topic, I'd like to see that 12MHz Z80 do something actually useful. Impressive work, but can we move away from games and run actual applications? -- Take a look at the Magic-1 project for instance (not exactly the same, but the guy actually runs a web-server from it!)Before you jump the gun, I will add that I understand the complexity of Conway's game of life but that's all we see from home-made Z80s, etc. Just games... Why is that?Pardon my posture, I just had to ask.

author: im_a_human
author_rank: Regular Contributor
timestamp: November 26, 2010, 07:53:22 pm
content: Dont worryive got much more things i want to do with this. That 12Mhz Z80 computer isnt even finished yet! Theres another board to go on it which is going to be the analogue synthesizer for making music. Its still in the development phase. Two VCO's, an LFO, two envelope generators, a VCF, and a low pass filter and audio sampling. My 4 x 40 character display will come in very handy for showing the synths settings.

author: BlackCow
author_rank: Newbie
timestamp: December 09, 2010, 02:22:01 am
content: Those are very nicely put together!I've been working on an Intel 8085 based microcomputer.It has 32k EEPROM, 28k Non-volatile SRAM, a UART and an 8255 I/O controller (not yet wired up). It's still a work in progress, its been a lot of fun. I have it interfaced with a very retro terminal (much older than me) from 1979. In the picture below its hooked up to a small serial display.The ultimate goal is to have the 8255 IO controller interface with a floppy drive so that I can load programs into RAM off of a floppy.Unfortunately I have to hand assemble all of the code in a hex editor, I haven't been able to find any 8085 assemblers online.What do you use to assemble your Z80 code, and is there something like it for my chip? (or do you just hand assemble as well?)

author: im_a_human
author_rank: Regular Contributor
timestamp: December 09, 2010, 10:20:00 am
content: @blackcow hi, excellent work you have done there. ?I hand assemble all my code and write it out on paper then type it into the computers RAM?using a program called a monitor. It can be hell if i find a mistake when ive written a large program and have to re-write partitialy some of the code. There are assemblers for nearly all microprocessors. It can be difficult to find certain assemblers like thesesince the 8085 hasnt been around for quite a long time. I can only say dont give up searching.

author: joelby
author_rank: Frequent Contributor
timestamp: December 09, 2010, 01:14:03 pm
content: Quote from: BlackCow on December 09, 2010, 02:22:01 amHow abouthttp://gnusim8085.org/?

author: BlackCow
author_rank: Newbie
timestamp: December 09, 2010, 04:12:15 pm
content: Quote from: joelby on December 09, 2010, 01:14:03 pmGNUSim85 is a great program, unfortunately it is only a simulator but does not assemble your code out to a hex fileIts helpful for testing code though. Maybe I can write my own assembler haha.

author: joelby
author_rank: Frequent Contributor
timestamp: December 09, 2010, 04:31:38 pm
content: That's a shame. It does have an assembler, so you should theoretically be able to add a function to save the memory to hex once it has run, or convert it to a standalone utility.

author: Polossatik
author_rank: Frequent Contributor
timestamp: December 10, 2010, 04:59:07 pm
content: Quote from: BlackCow on December 09, 2010, 02:22:01 ama quick google for 8085 assembler yield a few likehttp://www.planet-source-code.com/vb/scripts/ShowCode.asp?txtCodeId=63780&lngWId=1and payed (25 € for personal use)http://www.oshonsoft.com/8085.htmlnot checked anyone of them..Can't recall what I used early 90's with the 8085 style stuff i made ..

author: im_a_human
author_rank: Regular Contributor
timestamp: January 31, 2011, 12:56:18 pm
content: Hello again everyoneI had to go and build a larger 16x16 LED matrix. Heres a photo of it during construction...

author: im_a_human
author_rank: Regular Contributor
timestamp: January 31, 2011, 12:58:29 pm
content: And here is a photo of the finished board showing Conway's game of life...aaannnd I will have a youtube shortly...

author: im_a_human
author_rank: Regular Contributor
timestamp: January 31, 2011, 02:30:35 pm
content: Ok here is a short video demonstrating the game of life. enjoy... oh and i will try to post a circuit diagram soon as this is a very straightforward design and could be adapted to any micro controller or computer project.

author: im_a_human
author_rank: Regular Contributor
timestamp: December 30, 2011, 12:39:01 am
content: Hi everybody, its been quite a while since i last posted any topics but i have finally got round to drawing the circuit diagram for the 16x16 LED matrix. I used the free CAD software called Design Spark for this then i exported it as a .PDF file. You could use this with any microcontroller or computer with two 8 bit parrallel ports.

author: im_a_human
author_rank: Regular Contributor
timestamp: December 30, 2011, 01:27:52 am
content: I probably briefly mentioned in another post i made that i cant find now that i will be building a MIDI sound synthesizer into the most recent Z80 computer ive been building. (the one with the 12Mhz clock). After about nearly 2 years of trying out different ideas with analogue circuits built on breadboards i wasnt satisfied with the sound. The oscillators and filters sounded thin and weedy and theres not enough board space to implement a true classic synth design with all the dozens of discrete transistors circuits. So i decided to go for the digital option. Ive been doing a bit of PIC projects and programming over the last 9 months or so and using MPLAB and the free C compilers and the PICKIT 2 and 3. I was looking at the PIC's available and saw the DSPIC33F series. Ive seen on youtube theres a guy who implemented a DSPIC synth design and it sounds fabulous so that reasured me this was a very good path to take.So i bought some DSPIC33FJ128GP802 parts because these come in DIP packages which is good because its going on verobard and also because it has stereo 16 bit DAC's on the chip. It took me several weeks to get my head around the datasheets and the refrence manuals and get the oscillator running for this part but now i do have a photo of my initial setup for developing the project. It only blinks an LED at this moment in time but it does run at 40Mhz. here it is...http://www.flickr.com/photos/32042005@N05/6298918077/#First i want to create a VCO for sound waveform generation and i realise that digital signal processing can be frightingly complex subject but im not going anywhere fast and im not a quitter. If you have any questions please ask. Thanks for reading and i will be back soon.

author: Rufus
author_rank: Super Contributor
timestamp: January 21, 2012, 11:24:58 pm
content: If anyone from this thread is still hand assembling code, I wrote simple (one source file, hex and list file output) 8085 and Z80 assemblers years ago.Will be DOS executables if I can find them, might be able to recompile for Win32.

author: im_a_human
author_rank: Regular Contributor
timestamp: January 22, 2012, 05:13:39 am
content: Hi Rufus, Hey that would be great as i dont own a PC based Z80 assembler so i would be very interested in using your Z80 assembler thanks, please could you send it to me. Thanks.

author: Rufus
author_rank: Super Contributor
timestamp: January 22, 2012, 05:55:48 am
content: Quote from: im_a_human on January 22, 2012, 05:13:39 amI just compiled them for Win32 with no real testing so it might have caused some problems. Both assemblers are attached.doasmz80 -l tryand look at try.lst for basic documentation I wrote for someone else I gave it to about 20 years ago, the 8085 assembler is very similar.edit:- should have known I would screw up something, changed the attachment to just the z80 version which now hopefully doesn't need any DLLs. If someone wants 8085 version ask.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: January 22, 2012, 10:19:04 am
content: Quote from: BlackCow on December 09, 2010, 04:12:15 pmNot used this myself but if it is half as good as his Pic simulator then I can strongly recommend it. It'shttp://www.oshonsoft.com/and he does an 8085 (and Z80) simulator/ assembler and disassembler for 25 euros may be worth a look. You can also download a 30 trial for free. Hope it helps

author: Lawsen
author_rank: Frequent Contributor
timestamp: January 22, 2012, 07:08:23 pm
content: My only experience with the Zilog 80 was the Timex Sir. Clive Sinclair computer with the membrane keyboard and it costs a mere $99.00 USD, which was a lot for a teenager at the time and the minimum wage was a mere few dollars per hour. It out lasted my brother's Macintosh SE/30. It depends upon a television set as a display.

author: im_a_human
author_rank: Regular Contributor
timestamp: January 23, 2012, 11:52:46 am
content: Thanks for the assembler RufusIts got a few bugs in it but it does work.

author: Rufus
author_rank: Super Contributor
timestamp: January 23, 2012, 01:21:22 pm
content: Quote from: im_a_human on January 23, 2012, 11:52:46 amMore bugs than documented?

author: im_a_human
author_rank: Regular Contributor
timestamp: January 23, 2012, 08:46:39 pm
content: Yeah in afraid so. It dosent output the correct values in the list file for some instructions and the hex file dosent contain the correct bytes always.

author: Rufus
author_rank: Super Contributor
timestamp: January 23, 2012, 09:57:38 pm
content: Quote from: im_a_human on January 23, 2012, 08:46:39 pmI haven't looked at it in 25 years but if at the time I documented subtle bugs like INC (IX+IY) not being detected as invalid syntax I would be surprised if I missed something fundamental like generating incorrect code.

author: im_a_human
author_rank: Regular Contributor
timestamp: January 29, 2012, 08:51:54 pm
content: Hurray!!!Finally got my dsPIC33F to do something more interesting. A waveform at last! The software simply increments a counter from 0 to 65535 in increments of 255 and outputs the value to the DAC. I tryed just outputting every increment from 0 to 65535 but it made a waveform that had too low a frequency to be displayed on the scope for a photo to be taken. anyway next im gonna try to create an array for a sine table and see how that goes.

author: im_a_human
author_rank: Regular Contributor
timestamp: February 23, 2012, 12:57:50 am
content: Ive shed much blood sweat and tears getting this thing to work properly but ive got the hang of it nowHeres a pic of my dsPIC outputting two sine waves at 2KHz and 4KHz...http://www.flickr.com/photos/32042005@N05/6921718559/#and a closer view of the oscilloscope...http://www.flickr.com/photos/32042005@N05/6921786149/#and heres a demonstration of summing a 2KHz and a 4KHz sine wave together..http://www.flickr.com/photos/32042005@N05/6921804251/#

author: steve_w
author_rank: Regular Contributor
timestamp: February 26, 2012, 12:55:18 am
content: Love your work.I think I was your Australian doppleganger, In the eighties I went to tafe (technical college for non aussies) and did industrial control on z80 among others. I used the z80 in my final year project and made a plotter where the z80 had a centronics interface and drove x and y stepper motors under a pen. worked ok for a project but sucked as a plotter.regardssteve W

author: im_a_human
author_rank: Regular Contributor
timestamp: February 26, 2012, 05:31:51 pm
content: Projects don't always work out first time, especially at college when your pushed for time. You have to often work in groups and your group members sometimes don't have the same skills or knowledge as you and then you have to compromise because the guy who's part of the project he had to do to isnt how you planned it or it isnt finished or you get side tracked because you spent too much time in the pubs and clubs and ran out of time.

author: steve_w
author_rank: Regular Contributor
timestamp: February 27, 2012, 08:15:06 am
content: You must have been thereI'll be following your posts with interest.regardsSW

author: im_a_human
author_rank: Regular Contributor
timestamp: March 05, 2012, 07:53:04 pm
content: Hi, and thanks to everyone who is following this postI have a closeup picture of my breadboard with the dsPIC33 on it. I have got the two 16 bit on chip DAC's running perfectly and capable of outputting signals upto 50KHz on each one.Also i Have the UART running too after about 2 weeks of intense head scratching and datasheet reading. I connected it to the PC with a second USB port and used a Arduino USB to serial converter board to interface to the dsPIC. I have Hyperterminal running in windows and after much trial and error got the communication running very smoothly without any errors and all at the same time as the DAC's sending out audio.Im over the moon that i have got this far

author: Polossatik
author_rank: Frequent Contributor
timestamp: March 08, 2012, 04:15:19 pm
content: congrats!

author: steve_w
author_rank: Regular Contributor
timestamp: March 13, 2012, 01:42:37 am
content: Keep the posts coming - excellent work.

author: l4rtt-1
author_rank: Contributor
timestamp: March 14, 2012, 03:56:45 pm
content: Interesting projects!How do you program the DSPic, can you use pickit?

author: im_a_human
author_rank: Regular Contributor
timestamp: March 14, 2012, 06:16:52 pm
content: Hi,Yes the pickit 2 and 3 work very well with dsPIC. You have to use MPLAB and install the C30 compiler also. Then you can write your code in 'C'. You can write in assembler also but 'C' is much easier.Im now writing the code to recieve the MIDI data from the UART and make the ADSR (Attack, Decay, Sustain, Release) type envelope generator that will shape the volume of the notes when played. Its going to be monophonic (only plays one note at a time) for the time being because its an easier goal to achieve. Hope to have that finished in another four weeks. (fingers crossed)

author: im_a_human
author_rank: Regular Contributor
timestamp: March 26, 2012, 07:16:04 pm
content: Hi everyone!Ive actualy started to build some hardware atlast!A few photos of stages of build which is by no means complete yet.I decided to use no less than four dsPIC33 devices in the design of my synth. This will give me alot of processing power and alot of flexibilty to create different patches of oscillators, frequency modulation, envelopes, LFO, filters, and different effect types suchs delay, reverb, chorus, flanger etc.

author: adept
author_rank: Regular Contributor
timestamp: March 26, 2012, 10:21:03 pm
content: If you like Z80 computers, have you ever heard about n8vem? It's a google group that all they do is make Z80 computers. They all fit on a single board. They sell the boards, have a parts list, and all the chips are DIP. I was going to build one, but the fact is that they cost a lot of money to build. The EEPROM and the SRAM are the killers. They cost about 10 bucks a piece! Not to mention you can't find them anywhere. I think SRAM is really cool. DRAM takes too much CPU power just to keep the data in the modules. It all is a waste of resources. (though it is WAY cheaper and faster...) Anyway, thought you might find that interesting!

author: l4rtt-1
author_rank: Contributor
timestamp: March 27, 2012, 08:03:00 am
content: Quote from: im_a_human on March 26, 2012, 07:16:04 pmNice! Keep us updated!

author: steve_w
author_rank: Regular Contributor
timestamp: March 27, 2012, 08:13:30 am
content: Nice job, i like how straight you made the wires :-)