Sinclair ZX80 / ZX81 / Z88 Forums

Hi,

This project is based on the electronic assembly published in "Electronique pratique" #166 around the UM5100 circuit.
The schematic is practically the same as the one given in the datasheet, but the interfacing to the ZX81 gives it interesting possibilities.
- 16 x 8K memory blocks (128kb RAM) Save by ROM poking ($0000-$2000), and retrieved using an IORQ (IN $7F).
- RECORD & PLAY available on a OUT $7F.
- Recorded sound (8 secounds blocks) can be stored in a file in raw or compressed format.

Original wiring diagram:
http://zx81.ordi5.free.fr/brico/deltasound

My wiring diagram:

Hi,
This project can easily run on a ZX Spectrum but add to be update on the edge connector (A8 to A12 pins).

Changes:
-EO memory cleaned and UM5100 A14 desactivated.
-Minors changed.
This wiring diagram is in progress...
I had to check all components values.

HI,

The wiring diagram seem ok.
- The d4 (Reset counter) was not drived by the IORQ !
- The UM5100 memory latchs was wrong.
- TS1500/Spectrum PCB profil (You had to change the connector!)
- This PCB is a little high, which is why a horizontal version could be considered.
- This circuit is stand-alone,and can be test without the computer at first.

If any ideas, let me know.

This first project isn't tested, and come without warranty.

New wiring diagram: Kicad project:
http://zx81.ordi5.free.fr/brico/deltasound/

Have Fun...