OpenSpand announcement

[nollkolltroll]

I've been working on this project for a while now, and today I realized I have implemented every function I want and see no showstoppers. Still some ways to go.

What is OpenSpand? It's like a ZXpand+ with some extended features:
* 56KiB of RAM with software configurable mapping and size.
* MicroSD card storage with transparent LOAD/SAVE integration.
* Embedded support commands in an overlay ROM for instant availability.
* Uses the latest ZXpand ROM, "Tomte".
* Supports pseudo high resolution graphics.
* Supports true high resolution graphics, WRX.
* Supports user defined characters, CHR$64 and CHR$128.
* Dual emulated AY-3-8910 or YM2149 sound chips, model selectable.
* Stereo sampled sound output via the LEDs.
* Joystick connector, standard 9-pin ATARI compatible. Several modes of reading. Also sends data via keyboard injection.
* Serial I/O via extension connector. Connect to RS232-buffers, MIDI-buffers or Serial2USB module.
* ZX81, ZXpand+ or Big Bang X2 rom selectable.
* A reset button to save wear on the power jack connection.
* A configuration button to enter the config menu.
* Configuration via ZX81 keyboard.
* Firmware update via USB.

The ZX81 internal ROM and RAM are always disabled via /ROMCS and /RAMCS, OpenSpand supplies all the memory needed.
It is designed to be fairly easy to solder by many, and cheap to produce.
The hardware design and software will be open source as soon as it is more complete.

SirMorris has been a BIG help in this endeavor, giving me his blessing and source code to use.

Read about some of my development:
https://hackaday.io/project/201943-open ... -expansion

EDIT:
- Added selectable roms.

[Moggy]

That looks mightily impressive Adam! Just as impressive as your audio work for the spand.

Rather than use the TOMTE ROM code why not use the Big Bang X2 ROM which is now in use on both the classic and spand+ thanks to Kmurta who made it so. I have it on two of my spands and it works great.

Could your audio software work with this in the same way as the regular spands?

[Paul]

Wow!
Thats amazing
I love to see the 2350 used and look so much forward to using it on one of my ZX80s
And I'm keen to see the sources because i was barking up a similar tree.
I only have the first pcb design based on a PGA2350 but my firmware is basically non existent.
Keep up your great work and I'm very glad it has Charlies blessings

[Spinnetti]

throw VGA on thereand a z80 processor, throw it in a stock case and you have the ultimate zx81

[nollkolltroll]

Moggy: yes, the sampled audio player works with this. It also supports stereo sampled sound output, but software would have to be written by someone
I may also add support for A-law audio decoding (logarithmic 8-bit values converted to roughly 13 bits), but that is far down on the list.
I had totally forgotten about Big Bang X2, thanks for the reminder! It is very easy to add more roms, so a choice between Tomte and BBX2 will be added shortly.

Spinnetti: I have had SO much trouble with feature creep! The only thing majorly stopping me from adding more features is lack of GPIO. More I/O and it would probably have DVI and composite video output.

Paul: sadly I have no ZX80, the ZX80 clones Minstrel2 and TL801 will be tested in due time so you hopefully get an indication of ZX80 compatibility.

[nollkolltroll]

Paul: thanks for the repost on zx81.de! I try to stay up to date and read it from time to time, but have no real skills in the German language so have no account there.

[1024MAK]

Shocked

But in a good way

That's good progress

Mark

[Paul]

Paul: sadly I have no ZX80, the ZX80 clones Minstrel2 and TL801 will be tested in due time so you hopefully get an indication of ZX80 compatibility.

If you are interested in getting an original ZX80 I might be able to help. I own some of them and I added the ZXPand routines to the ZX80 ROM several years back.
I dont easily part with my ZX80s but I definitely woud to someone who contributes to our community like you do.
I have no idea of what hackaday.io does but I guess you have hosted your project somewhere.
I would like to participate and contribute to it.
Unnecessary to say I'd love to get a prototype and help with testing and developing

[sirmorris]

As a well-known cummudgeonly judge on a popular ballroom dancing-based television show would say - A-MAZ-ING!

[Paul]

Nice to read you Charlie