IBM 5150 PC Cassette Port

[mmruzek]

Hello, I have built a homemade cable to try using the cassette port with Cassette Basic on an IBM 5150 PC. I am finding the information on using the cassette port really sparse. I have been able to send a file listing to a battery operated cassette player OK, as it sounds reasonable to the ear. However I only managed to do that by tweaking the volume level on the cassette player, which may have automatic volume control. I can't seem to read the file though while playing with the volume settings, etc.

Anyway, I am wondering if anyone has seen a good detailed account of using the IBM 5150 cassette port, with some tips and suggestions that will save me from re-inventing the wheel. Otherwise I will have to pull out the digital oscilloscope and really dig into this. Thank You, Michael

 

[billdeg]

Use a trs 80 cable with a stripped connector. I did not get very far earlier this year in my own experimenting. The IBM hardware reference that describes the cassette port. I just did not spend enough time with it, but it's worth doing let us know how it goes

 

[patscc]

I don't recall the cassette port being all that popular, except for stupid tricks like using the motor on signal to trigger relays, and stuff like that.
patscc

 

[tezza]

I got mine to work ok a few years ago. I'm pretty sure I used a TRS-80 Model 1 cassette cable. However don't quote me on it. It was a while ago and I didn't note it down anywhere. I THINK the pinouts are compatible though.

Tez

 

[modem7]

I presume that "sparse" documention included the two settings of the cassette jumper on the 5150 motherboard.

I have not done any cassette recording/playback with the 5150, but I remember from the eighties (using a Microbee computer) that it could be quite finicky. One had to get just the right combination of recording level plus playback level (with certain bounds). If one was wrong, the whole operation didn't work.

 

[mbbrutman]

A "standard" TRS-80 cassette recorder cable works unmodified on the IBM PC. If you want to move into the 21st century, digital devices are usable too - I've converted a cassette recording of the IBM PC diagnostics into an MP3 and played it back to the PC using the sound card on a Thinkpad.

For those of you interested in the underlying recording mechanism ...

http://www.brutman.com/Cassette_Waveforms/Cassette_Waveforms.html


Mike

 

[mmruzek]

Thank you everyone for your help. I was able to save and load a cassette program on a 5150 PC (Actually the PC-Retro) with success. Attached is a file containing additional information about wiring a cassette port, with my handwritten notes and comments.

What was I doing wrong? Well, I had the data input and data output mini-plugs going to the wrong jacks on the cassette player...LOL. See my note on the wiring diagram.

Also, here is a screenshot of a typical cassette basic terminal session. Notice that there is no space between the save" and the file name you are using. It's the same format for command load" (It took a while for me to figure that out too.)

Finally, don't start this project without taking a look at Mike's webpage. Some good info there...

Have Fun. Michael

 

[bettablue]

actually do use mine. And, you're right about the TRS-80 cable. They use the exact same pinouts. The main reason for mine is that I do tend to play around wuth BASIC. And to be honest, what brings out the geek factor than by loading a program you wrote via the cassette recorder/player. It takes a little playing around with to get the proper volume adjustment, but for my minimal use, it works pretty well.

I got mine to work ok a few years ago. I'm pretty sure I used a TRS-80 Model 1 cassette cable. However don't quote me on it. It was a while ago and I didn't note it down anywhere. I THINK the pinouts are compatible though.

Tez