TRS-80 Data Dubber (cassette fixer)

[DrG]

In the olden days, we suffered with TRS-80 cassette tapes. These were the mass storage device that we used before floppies and HDs. They were extremely sensitive to volume settings and pretty much everything else it seemed. You would load in a long program watching the asterisk blink...hoping it would complete.

It was such a big deal that several circuits appeared to "condition" the audio before it went into the TRS-80. The one below was probably the best - it was given to me (I think in exchange for fixing something or programming something - it was so long ago, I can't remember). It was suitable for make copies of cassettes as well as just using it in between the cassette player and the TRS-80.

For reasons that are not clear to me, I decided today to investigate it further.





The schematic for the Data Dubber was published in a hobbyist magazine called 80-Microcomputing.


and you can read the complete article from that issue here: https://archive.org/details/80-microcomputing-magazine-1980-02/page/n52/mode/1up

So after some reading and cleaning and so forth, I figured I would test it out. I am not yet ready to reincarnate my TRS-80, but if I could find a tape and a cassette player and figure out to see the waveforms on my little digital scope (which is not at all easy for me...at least not yet).

I did find my copy of Sargon II - a terrific chess program at the time (at the highest levels, it would take hours).


So, I futzed with my scope and got a pic of the waveform as it comes from the cassette player (top) and when it is ready to enter the TRS-80 (bottom).



Looks to me like this thing still works!

[rfclown]

I had the same thing... but it wasn't in a nice box. I think I bought it as a kit (PCB and parts) and never put it in a housing. It did help.

I never had or used Sargon, but I read about it. It was programmed in assembler. Can you imagine anyone writing a chess program in assembler? At the time, it was a good chess program.