The Tiny 12 is a microprocessor from Atmel. It is in a 8pin package. 

Instead of building project with capacitor & resistor and audio
transformer, we build project with "0" and "1". Much cheaper. Much easier
to change. 

The Tiny 12 microprocessor has built in bootstrap loader, so it can be
connected to the PC LPT PRINTER port to download the program from the PC
into the Tiny12. It has electrically eraseable memory, so no ultra-violet
light needed. Also the IC can be reprogramed, so don't have to throw away
after use.

The 7+ includes .bmp schematic and source code (DTMF.ASM). Is is zipped
with WINZIP, so if there is an error, it is because you use pkzip and not
WINZIP.

1) So, get the program source code (included here as DTMF.ASM).
2)  Assemble the source code (with DOS the program AVRASM, for Windows the
program WAVRASM). This will create object code in HEX file format.
3) Use (for DOS SP12 program) to transfer the HEX file to the Tiny12 via
the PC DOS LPT port.Please set TINY12 fuses to  01011010 (or $5A)

This little program generates DTMF sequence and repeats DTMF sequence
again. It is for you to change to learn about microprocessor. Program also
makes fine AM signal at 32Mhz with 15.625kHz sidebands!

73s let me know how it worked out,

Rob ZS1AGX
