ZXadlib CPLD-free

MC68k

Hi folks.

Repost from here

OPL2 chipset for speccy. 6Fh index, 7Fh data. This is first prototype with homebrewed PCB.



I already made new layout and second prototype. It's still unfinished - audio connector and few capacitors not soldered yet, but i think this is final design. PCB also homebrewed.



DIP-only chips and thru hole components. One side PCB, easy to make at home. No need to use CPLD, when one logic chip can do the job.

I have about 20 original chipsets, so can make 20 assembled units and some bare PCB's for those, who buying parts by themself.

More CPLD-free projects coming soon.

P.S. Black_Cat, please keep your comments. Thanks.

Zetr0

This is very nice!

Thanks for sharing your efforts!

1024MAK

Zetr0 wrote: »

This is very nice!

Thanks for sharing your efforts!

Yes, what Zetr0 said :p

Welcome to WoS forums :-)

I look forward to more pictures ;-)

Mark

slenkar

is it a spectrum clone or what?

guesser

slenkar wrote: »

is it a spectrum clone or what?

It appears to be an OPL2/AdLib soundcard for the spectrum...

http://en.wikipedia.org/wiki/Yamaha_YM3812

MC68k

Thanks for your welcoming :)

Connector for original speccy. Also first 5 units will go with small demo programm on the tape.

@guesser That's right adlib soundcard for speccy. This chip also used in some "toy keyboards"

Yerzmyey

As a hobby project it is very cool.
As a possible new standard, it's not so cool. Multiplying of standards can be actually harmful, You know.

There already is the Yamaha FM sound-card (2 Yamahas = 6 channels of FM sound + 6 channels of regular AY sound) for Spectrum and it is TurboSoundFM, even with a PC tracker.
http://velesoft.speccy.cz/turbosound-cz.htm

http://velesoft.speccy.cz/turbo_sound/nedopc/tsfm-space_standart%20(shiru).mp3


As far as I remember, also Zaxon sells his interfaces, that use the standard procedures, the most common on Spectrum.
http://www.worldofspectrum.org/forums/showthread.php?t=45883&page=4

guesser

Yerzmyey wrote: »

As a hobby project it is very cool.
As a possible new standard, it's not so cool. Multiplying of standards can be actually harmful, You know.

The biggest problem I see with it as a standard is that with a single logic IC and the ports given, I assume it is only monitoring two address lines :-)

Google shut Freebase down so alas I can't use Philip Kendall's handy dandy port checker to see what clashes there are :(

1024MAK

One address line for the sound chips register selection, plus three address lines for the 74LS138's A, B, C inputs plus one or two address lines for the 74LS138's enable inputs leaving one active low enable input on 74LS138 the for /IORQ line.

So maybe six address lines. Not sure what function the three diodes are doing, but they could increase the number of lines decoded.

Now if you want to improve on this, use a 8 bit comparator like a 74HCT688 then you can decode 7 address lines (and not needing any diodes) leaving one address line free for the sound chip :D.

Mark

guesser

Aha!
I only saw the original pic and couldn't read the part numbers on that :)

kpuchatek

Great !
I always wondered what ZX can do with that - Adlib files were usually quite big
with instruments bank, and even more space is needed for MIDI files.
Anyway, very interesting and should be quite easy to build thanks to DIP.
Please publish schematic, so maybe it will get some popularity.

cmonkey

Very nice. I wish someone would make an OPM (YM2151) add-on board for the Spectrum.

kphair

This is very cool and despite what some people might think, it's always nice to have new hardware on the Speccy, especially with such a neat, compact board layout. Might have to dig out that old SoundBlaster card...

All we need now is a port of AdPlug! :-)

MC68k

Thanks guys.

@guesser thats right, japanese made motorola logic chips have marking, which quite hard to read. It's a same '138 decoder and quad amp.

@kpuchatek it depends on file format. Some of them quite compact. Main point was to keep all parts "thru hole" and design single side PCB. I will release all information after complete debugging.

@cmonkey GOSH!!! It was my top secret project until your post :o

@kphair It took some time to toss around chips and other parts to keep spacing, thickness of traces, height of the parts and location of the audio connector. Same time keep it with common parts(i know about '688, but '138 much more common)

Lots of people asking me, why i don't use CPLD or GAL. I have few reasons for that.

First of all - i believe that electronics have to be an art and CPLD is not. Look at original MultiFace, how neat it was done with simple logic chips.

Second is - always trying to make add-on with common technology for lifespan of the hardware plus 2-3year. So GAL is kinda ok, but if i can, i will not use GAL. Also trying to keep manufacture date of the parts(except el caps) in the same time frame if possible.

And third - device should be simple and easy to make at home without $$$ soldering stations and special equipment.

Remember, it's very simple to make complicated thing, but very complicated to make thing simple.

1024MAK

Now where is that like button? :p

Mark

cmonkey

MC68k wrote: »

@cmonkey GOSH!!! It was my top secret project until your post :o

Please, please, please tell me that you're being serious here and that this isn't some kind of cruel joke!!!!!!! I'd die for an OPM add-on!!! Just to be able to play the original Out Run tunes on a Speccy would be more than awesome!! :grin:

MC68k

@cmonkey no, this not a joke, even don't think, as you can see this photo

Zetr0

@MC68k

I think Christmas just came a little early for cmonkey!

=)

Yerzmyey

despite what some people might think, already existing hardware is not new hardware.

because of that I didn't "wonder what ZX can do with Adlib-like interface", as it was known for years.

cmonkey

MC68k wrote: »

@cmonkey no, this not a joke, even don't think, as you can see this photo

You, sir, have just become my no.1 fan!!! Thank you so much for making one of my dreams come true! I've wanted OPM on Spectrum for a very long time and now the wait is nearly over :smile: