My Home Made Z80 Computers

[im_a_human]

Thanks for the assembler Rufus  Its got a few bugs in it but it does work.

[Rufus]

Thanks for the assembler Rufus  Its got a few bugs in it but it does work.

More bugs than documented?

[im_a_human]

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.

[Rufus]

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.

I 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.

[im_a_human]

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.

[im_a_human]

Ive shed much blood sweat and tears getting this thing to work properly but ive got the hang of it now

Heres 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/#

[steve_w]

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.

regards

steve W

[im_a_human]

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.

[steve_w]

You must have been there

I'll be following your posts with interest.

regards

SW

[im_a_human]

Hi, and thanks to everyone who is following this post

I 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

[Polossatik]

congrats!

[steve_w]

Keep the posts coming - excellent work.

[l4rtt-1]

Interesting projects!

How do you program the DSPic, can you use pickit?

[im_a_human]

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)

[im_a_human]

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.

[adept]

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!

[l4rtt-1]

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.

Nice! Keep us updated!

[steve_w]

Nice job, i like how straight you made the wires :-)