Tandy Radio Shack Computer Cassette Recorder (TRS CCR) Usage

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PART 5: Example Usage of Cassette and Smartphone/Tablet

The intent of this section is to demonstrate how a CTR (cassette tape recorder) is used with one of these devices. Specifically, I show usage with a Tandy Color Computer 1 (16KB version), but the physical setup is essentially the same for all the PCs that use these devices.

NOTE: Two links for instructions on how to construct the necessary 5-pin DIN cable for TRS-80 systems…

The built-in BASIC ROM of the Tandy machines (and the IBM PC 5150) support the cassette operation. Two additional cartridge-programs that support cassette save/load are:

  • Dungeons of Daggorath (ZSAVE/ZLOAD)
  • Orchestra-90 CC Stereo Music Synthesizer (WRITE/READ)

Connection

Here are images of how the cables are connected. I have both the original Tandy cable, and an “aftermarket” constructed cable. They both work fine with original equipment, however the original Tandy cable (with mono-plug connectors) I haven’t gotten those to work well with a modern PC (laptop). But I did get the “aftermarket” cable (that has stereo plugs) to work with a laptop (more details further below), and I also did get the original Tandy cable to work with a tablet (iPad).

The audio plugs of the cable (typically) aren’t labeled, For the Tandy original cable, the “off-color” cable (black) is “EAR” (headphone) and the “two-matching-colored” cables (gray) are REM (smaller 2.5mm jack) and AUX/MIC (3.5mm jack). Custom build cables should follow this same convention, but not all of them do. If uncertain, an alternative is to just use trial and error – using the wrong plug won’t harm the PC or the device, and there are only two choices to try.

Trial and error is just turning on the machine, typing a simple BASIC program (below), and try to SAVE and LOAD it back. If it fails, then try reversing the EAR and MIC cables.

10 ?”HELLO”
CSAVE

NOTE: The original TRS-80 and CTR-41 manual indicate to use the AUX jack (for TRS-80 Model 1), but for my use on the IBM PC 5150 and CoCo1, I’ve always used the MIC jack.

PC/Laptop Connection (using traditional headphone/microphone jacks)

Using a “modified” TRS-80 cassette cable (that has stereo plugs for the AUX/MIC connector), I was able to use a laptop as a cassette recorder (see cable images above for visual difference). Modern PCs tend to come with a built-in microphone (sometimes more than one), so those internal ones need to be disabled. The 3.5mm microphone jack should be the only enabled audio input source. Then in addition, both the microphone and speaker “level” (volume) should be reduced from max to about 70.

The modern PC will be digitally encoding the analog audio during both recording and playback – so the precision of that encoding will be very important. That precision is in “Hz” (or samples per second). I don’t know which Hz is “good enough” for recording cassette-data tapes – for example, CD-quality is generally 44.1KHz. As a “just in case” provision, I set the microphone and speaker to the highest “Studio Quality” the hardware supports (in my case, 192KHz). This will make the resulting data files much larger, but should ensure SAVE and LOAD operations work across all scenarios (i.e. some data may be easier than others to encode, which means a lower setting may work in some conditions and not others). At least when working with a PC as the device, we won’t have to also worry about the condition or quality of any tape media (and the digital files will never degrade).

How to apply these settings will vary by Operating System and hardware drivers being used. In the example below, I used Windows 10 and the built-in audio hardware of a DELL Latitude laptop. You could use a desktop PC as well, but might need stereo audio extensions since the typical Tandy cassette cable is under two-foot length. Modern PCs won’t support the REMote plug, so you have to manually handle when to PLAY and RECORD (more about that is described in sections further below).

Typically for Windows, if you right-click the Speaker icon on the taskbar, you have a “Sounds” option. In the settings dialog that opens, you’ll need to adjust settings under both “Playback” and “Recording” tabs…

NOTE: I use a “regular” phone/audio jack. It may be possible to apply these same settings with a USB connected device but I haven’t yet personally verified that configuration – the steps should be essentially be the same, but device names will be different.

RECORDER SETTINGS

  • Identify and rename the “internal” microphone of the device. This is just to ensure the correct one is being disabled. I did this by trial-and-error: disable all of them, then enable one at a time – do a voice recording, if that recording succeeds then that entry needs to be disabled. Also, you can rename Windows devices – so once I find which one is the internal microphone, I appended “INTERNAL” to its name.
  • On the remaining (one) enabled Microphone entry, right-click and choose Properties
  • On the General tab, there should be some reference to an audio jack being used (this is just a confirmation that the right entry is being used, no actual change in setting is needed)
  • On the Listen tab, ensure that “Listen” is turned off
  • On the Levels tab, set the microphone down to 70 (and set boost to 0)
  • On the Advanced tab, pick a Studio Quality higher than DVD

PLAYBACK SETTINGS

  • Similar to microphone, modern PCs may have multiple speakers or audio outputs. We just need to check settings on whichever one corresponds to the 3.5mm jack.
  • See Properties of the Speaker (right-click, select Properties from sub-menu)
  • On the General tab, check that the jack information is related to the 3.5mm jack (just a verification)
  • On the Levels tab, reduce from full throttle (100%) down to 60-70 (and avoid adjusting the system volume later, when LOADING/PLAYING cassette data recordings). If this setting is too high or too low, I noticed during a CLOAD the load would abort early and the CoCo would just reset itself.
  • On the Enhancements tab, select “Disable all enhancements”
  • On the Advanced tab, pick a Studio Quality

With these settings, I was able to SAVE/LOAD data using the Color Computer, in both ROM BASIC and a couple cartridge applications (all with these same settings). I use the regular “Voice Recorder” application that is included with Windows. But there are some details to be aware of, since the REMote plug is not in use here:

  • When about to SAVE data, start the recording a second or two before initiating the SAVE. On a CTR/CCR physical recorder, you would press RECORD+PLAY at the same time. With the REMote plug, the recording wouldn’t start until cued from the PC (via the REM plug). Since we don’t have that REM plug in this setup, we have to manually initiate the recording before it starts on the PC side. You can use digital audio editing later to trim empty content from the audio recording, as needed (i.e. the portion before the actual data stream just needs to be a moment, half a second would be fine).
  • Then conversely, when you want to LOAD data, do not play the recording until after initiating the LOAD. When you command a LOAD from the Tandy-device (or equivalent), it will “busy-wait” until the start of a valid data stream. If you begin playing the recording too early, the header of the data stream may get skipped. On a CTR/CCR physical recorder, you could leave the PLAY button down, and the device would use a relay to cue when the PLAY should actually proceed (via a signal on the REMote plug). Without the REM plug, this now has to be done manually.

BELOW: Example of using “ZSAVE” in the game Dungeons of Daggorath. Remember, the recording should already be in progress before pressing ENTER on the ZSAVE command. Also shown is using the “modified” Tandy TRS-80 cable (the original cable with all mono-plugs did not work for me). “ZLOAD” was then used to re-load the game-state condition (also verified after a complete power-cycle of the system).

BELOW: Example of using Color Computer built-in ROM BASIC to SAVE and LOAD a simple program (that converts degrees to radians). Again, this is using the “modified” TRS-80 cassette cable (with stereo plugs instead of mono).

  • 10 FOR I=0 TO 360 ' 360 degrees in a circle
  • 20 PRINT I; ' print degrees (";" stays on same line)
  • 25 PRINT " > "; ' show a conversion "arrow"
  • 27 D=I/180 ' divide out 180 "degrees"
  • 28 D=D*3.14159265 ' multiply by PI
  • 29 PRINT D ' print resulting value (no ";" goes to next line)
  • 30 NEXT I ' repeat for all degrees

NOTE: The original version of this program combined lines 27 and 28, but doing so ends up with a rounding error in this ROM BASIC. So this program is the “B-version” (DEG2RADB) that is more accurate.

NOTE: The CLOAD command will load whichever BASIC program is found next, so just play whichever recording file you want to LOAD.

EXAMPLE/INFO about Orchestra-90 CC Stereo Music Synthesizer

The infamous Orchestra-90 cartridge does work fine in this configuration. You can save compositions to cassette or PC/laptop recording, and load them later for additional editing and/or playback.

The only minor note is that the WRITE/READ commands for Ochestra-90 are particular about “filenames.” That is, to READ (load) you must specify the same name used during the WRITE. If you forget the name, or lose notes on what the names were, you can still do a READ “” (blank name) – while that won’t actually load any data, the program will still show the names it comes across while searching (so you can then “discover” what names are available, then rewind and load them with the actual names).


USING A SMARTPHONE / TABLET

Since I was able to SAVE and LOAD data with a laptop PC, conceptually I should be able to do the same thing with a smartphone (which is essentially a pocket sized PC). You can use an old smartphone, or old tablet that is WiFi-only (no SIM card or cellular access) – the only limitation is that the device must be able to run a sound recording app that can handle up to 96 KHz audio recordings (CD-quality is 44.1 KHz).

For this example, I am using an iPad Mini 4 (released in 2015). At time of writing, that iPad was running iOS 12.1. Unlike the PC laptop scenario described above, for this iPad tablet I am able to get the original TRS 5-din cable with mono plugs to work for both SAVE and LOAD.

CABLE SETUP (with iPad Mini 4)

I had to use BOTH of the following (and had them both connected at the same time).

  • Movo MC3 3.5mm TRS to TRRS Adapter (for SAVING) HERE
  • Apple Lightning to 3.5mm Headphone Jack Adapter (for LOADING) HERE

Other brands may sell a similar style adapter cable. They aren’t a very complicated cable, so I suspect any brand should work – just look for a cable length that works for you. I have a small stand for the iPad and can hide the cables behind there (the cables are shown in the image below just to emphasize how they are connected).

With both adapters connected (at the same time), everything works reliably. But like the PC laptop scenario, you must manually invoke the operations: (a) you start RECORD a moment before initiating a SAVE, and (b) you play an audio a moment after initiating a LOAD.

APP SETTINGS

The basic Voice Recorder App did not work for me (it did not have the necessary fine-tune settings). So instead I used the following AppStore app:

  • Voice Record 7 (free version works fine)

You will need to enable Advanced options during recordings. The main settings we used:

  • WAV (PCM) format
  • 96,000 Hz Sample Rate (or 96kHz)
  • Bit depth 24
  • Channels Mono
  • During Playback, I set Volume to 74 (40-50 was too low, loading would not work; between 70-80 is probably good)
  • During recordings, I left the gain at the default of about 5.2 (use the “Level Check” feature to monitor audio signals in real time)

EXAMPLES

And here are the results, shown below. Static images aren’t as exciting as a video for things like this, but I can confirm that I was able to SAVE and LOAD data for all these applications – consistently and reliably. The only issue to remember to rename the audio files to something appropriate to remember their content (the App doesn’t make it obvious on how to do this, but there is a little Pencil Icon for it – the default name is the timestamp of the recording).

SHARING TABLET WAV FILES

On a laptop, the WAV files are “right there” and easy to archive, copy, burn to a CD/DVD, etc.

But on a tablet: Apple does make sharing files unnecessarily difficult. Images (photos) are fairly easy to share (just plug into USB and open the DCIM folders), but other documents can be more difficult (e.g. using iTunes and setting up some Sync Folders, all that is very annoying).

Also, these WAV files will be fairly large, so e-mailing the files to yourself isn’t a practical option (and WAV files don’t often compress very well). I’d avoid converting to other formats (e.g. MP3) – it may work, some of the time, but it’s not a loss-less conversion (so you risk having a file that won’t load anymore). For encoded-data purposes, a high sample rate on these recordings is necessary.

So these modern platforms encourage the use of “the cloud” and large online storage services: dropbox.net, box.net, iCloud, OneDrive, GoogleDrive, etc. The “Voice Record 7” app supports all these, then also two other great features: “Send to FTP Server” and “WiFi Download.” Those familiar with FTP servers will appreciate that feature, but I think it is one file at a time (not a batch). The “WiFi Download” activates a simple web server, which you can then use that to download (or upload) WAV files from another PC on your local network. When activated, the App shows the details on how to use it (what IP, and a login to use).

Here is a sample of what the Apps built-in web-portal looks like:

RECORDING AUDIO FILE BACK TO TAPE

If you have a WAV audio recording file, you may want to record the contents of that file back to a tape (to then share that tape with someone who might not have a spare laptop or tablet).

For this, you’ll need a physical CTR (cassette tape recorder) or stereo deck with a tape drive unit. A modern one tape recorder will probably work, but these CTR/CCR from Tandy are also perfect for the task. But you can’t use the 5-pin DIN cable for this, you’ll need to use “regular” audio cables.

Plug the PC headphone cable to the CTR MIC. Rewind and set the tape index as desired. Press PLAY+RECORD on the CTR. Then press PLAY on the PC to play the intended WAV file containing the data-content to be shared. Make sure the PC/device has no other sound playing (and no pop-up notifications with audio). When the WAV recording is complete, press STOP on both the WAV file and the CTR.

  • (…TBD…)

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