TRS80 Model 100 using Windows PC as disk drive

After cleaning up my TRS80 Model 100, the next step was to try and load software to it. There is a lot of good information about this on

Portal of Light – TRS80 Model100

Using information from club100 I made my own D9 to d25 null modem cable. The 9 pin connector is for the serial port on the laptop, with the 25 Pin connector being for the Model100.



This is a very easy cable to make providing you can solder.

To set up a transfer of software between the PC and Model100 there are a couple of software programs to use. Again from the club100 site download the DL-ARC.EXE package. Note that the package won’t unpack on 64 bit versions of Windows.

Ensure your com port settings are set to 19200 baud, 8 bit, No parity, 1 stop bit, Xon/Xoff

Extract the file into a subfolder named C:\ROOT. I recommend taking time to read through the TEENYDOC.TXT file. Pay attention in particular to the sections:

  • Invocation via TEENY.CO file
  • Command Syntax (especially how to load and save)
  • Command Action


When you are ready to set up connect the serial cable and run TEENY.EXE

Follow the on screen instructions which step you through the process of transferring the Teeny program onto the TRS80.

Once you have successfully established the connection, its time to transfer something over to play.

There are plenty of games available for the Model 100. A good one is Portal of Light, available again from club100. Once a file has been loaded onto the Model100 (refer to the TEENY documentation) there are a few more things to know.

You need to understand the .CO files. The .CO file extension indicates a file is programmed in machine language. Often if you load a .CO file to the Model100, when you try to run the file it will just beep and do nothing. This means the file is not in the correct place in RAM. Note the following procedure to place the .CO file to the right location.

Go into basic and issue the following commands:

loadm” (where is the name of the file you wish to run)

3 numbers will show named “Top:”, “End:”, and “Exe:” followed by an error code. Note the “Top:” number.

In Basic, issue the commands:

clear256,XXXX (where XXX is the Top: number)
loadm” (where is the name of the file you wish to run)

When placing the bar cursor over the file and hitting enter it will run.

So now loading the Portal of Light game, and making the necessary configuration it is ready to play!


Its a good challenging game!



  1. I have a question. Do you know of someone who might transfer my “.co” files written on Tandy 3.5 disks with a Tandy Model 102 via the 3.5 external drive 2 that I hooked up to it. I would need it in a format I could read on my windows-based PC.

    I tried to read and transfer files from those disks with my USB 3.5 external drive plugged into my current windows-based PC, but it couldn’t see a thing.

    Ideally, I am looking for someone who is able to extract the files and put them on a flashdrive, but also in a format that I could read with a windows-based pc and a common word processing program.


    1. Sorry I’m not sure who could do that. I recommend looking for a forum with Tandy Model 102 discussion and posting a question there. I figured out how to transfer files from PC to the Model 100, but have not gone as far as copying files from 3.5″ floppy.

  2. Notice the keyboard wear from years of a user’s thumb hitting the space bar. Most Model 100’s you’ll encounter sport this kind of wear — they were so useful that people didn’t want to let them go.

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