Tandy 2500RSX audio recording via Deskmate

[mdanh2002]

Hi, I just bought a Tandy 2500RSX for a mere $10. This is the computer I grew up with - I spent many hours playing Deskmate on the Tandy 2500 as a kid.

The current machine has 2 floppy drives, a 1.2MB drive configured as A: and a 1.44MB configured as B:. The original Tandy 1.44MB drive died and I replaced it with another spare drive, which unfortunately has no DS0/DS1 jumper, and hence can only work as drive B on this machine. I tried many things to configure the 1.4MB drive as A:, including untwisting the cable as well as using a straight 34-pin cable, which did not work. The 60MB hard drive (which still works but is noisy) has been replaced with a 512MB CF card and everything is working fine.

One thing I would like to ask, how do you get Deskmate's SOUND.PDM to record audio from the microphone on this machine? Audio in games like Prince of Persia work well when configured for Tandy sound. Sound also works well in MUSIC.PDM (song composer) and in SOUND.PDM (for audio playback), but recording inside SOUND.PDM will only produce white noise. At the back of the case there are 2 holes, presumably for the 3.5mm microphone/speaker jacks, but there are no corresponding sockets on the motherboard. Good quality audio playback is done via the internal speaker, with volume adjustable through a knob at the back. The unit that I had, as far as I can remember, was able to record audio by speaking close to the condenser microphone which was mounted on the right corner of the case. There are no internal condenser microphone on the current unit. To prove the point, I still have the .SND audio file of my cousin singing a song as a 4-year old child, recorded on this machine.

If anyone knows how to record audio using SOUND.PDM on this machine, let me know. Or if the Tandy 2500 RSX does not support audio recording via the Tandy sound hardware, I would love to see some official specs or documentation mentioning this.

Thanks in advance for any information.

 

[Cloudschatze]

For reasons unknown, Tandy omitted the microphone jack and associated circuitry from the 2500 RSX and 2500 SX/33 models, as evidenced/supported by the following references:

Index to Tandy / RadioShack Computers

Q98318: Tandy DAC or PSSJ Windows Sound Driver

An Archive of Early Microsoft KnowledgeBase Articles

jeffpar.github.io

Where the prior 2500 models include the microphone circuitry, is it possible that you had one of those instead?

 

[mdanh2002]

Ah I see, thank you for sending the reference. Most likely I did not have the RSX but perhaps an earlier model. As far as I can remember it was a Tandy 386 machine with sound recording capabilities. Perhaps it was the 1000RSX not the 2500RSX. Now that I noticed, this unit is slightly bigger than what I used to have.

I opened up the unit today and located the missing audio input/output circuit components (attached photo). You can see the unpopulated components on the top left of the photo, near the Microphone and Audio labels. There are even unpopulated jumpers to switch the microphone socket to either LINE IN or MIC INPUT depending on the input source.

I do not believe it is hard to add back the recording circuitry. Let me purchase a microphone preamplifier board from AliExpress and feed the output into the audio chip. I will update this thread on my progress.
Thank you once again for the fast response!