Saving the Stringy Floppy: My small role in emulation development

Remember the Exatron Stringy Floppy (ESF)?  Of course you do!  This was the magical early 80s device that spared us TRS-80 Model I and III and clone owners from the tyranny of cassette tape in the days (1980-83) when we  couldn’t afford disk drives.  It saved my sanity on a number of occasions.

Required: One Stringy Floppy ROM for Emulation in Linux/Unix

Around the Net there are clever people who have built emulators for the TRS-80 Model I/III line of computers and just recently a couple of them decided the stringy floppy unit would be a good thing to incorporate into such programs.

I became involved with this project when Tim Mann put out a call for someone to capture (dump in computerspeak) a stringy floppy ROM image from a real stringy floppy unit for use in his emulator.  The stringy floppy ROM is a small 2k program which sits in the unit itself and adds commands to BASIC allowing programs to be saved and loaded from wafer.  Responding to the call, I dragged the old unit out of its box and powered up.  Thankfully, it still went (in contrast to some of my other vintage gear who at the mere whiff of a volt seem to throw an IC or capacitor)!

Grabbing the ROM was easy.  Just a matter of PEEKING at the memory area the stringy floppy ROM was occupying, then PRINT# ‘ing  it out to virtual disk file and getting it across to the PC via SVD and hence the NET.  The code was in a sequential data file on a virtual disk, but Tim was clued up enough to get it into straight binary so no worries.

So Tim had the stringy floppy ROM from me (and one other person) which he could incorporate into his Unix/Linux TRS-80 I/III emulator. All was good.

stringy floppy Emulation for Windows (with sound!)

Much our communication was done through the Yahoo TRS-80 forum, so other folk in the TRS-80 vintage world knew of this ROM-grabbing activity.  Being a Windows user, my emulator of choice is not Tim’s but Matthew Reed’s TRS23 program and in a posting on the forum I wished Tim well but regretted that I’d probably never use the finished product.  Imagine my surprise when I was contacted by Matthew Reed himself, who had been working on a similar thing for his TRS32 emulator.  Would I like to test it?

Of course I was happy to.  Apart a minor drive recognition issue, I found Matthew’s beta emulation worked well.  However, it was missing one thing.  Sound.  The stringy floppy makes a characteristic whirr (rising and falling slightly) as the tape in the wafer gets dragged around in its endless loop.  Matthew had incorporated the sound of spinning disk drives in his emulator so why not a working stringy floppy!

Matthew was warm to the idea.  Next problem was how to record it.  I took the simple approach and just sat a digital voice recorder next to the drive as it loaded a wafer (see photo opposite).  The resulting sound file was sent to Matthew and, after a bit of editing, it’s now its part and parcel of his TRS80 Model I/III/4 emulator.  What’s more, the stringy floppy was now part of an emulator I could use!

Cool!

Recovering stringy floppy programs from real wafers

The stringy floppy emulation activities didn’t stop there though.  The stringy floppy ROM provided BASIC loading and saving commands for programs but the full functionality didn’t only reside in ROM.  The rest was on a wafer owners got with the unit.  A program on this wafer, the Data I/O program, added BASIC commands like @INPUT, @PRINT etc. to the standard BASIC and was needed to read and write out data to wafers.

Now that Stringy Floppy emulation was available, that software also needed to be captured to virtual wafer, so the emulator user community had access to it.  There was other specific software too, such as the ESF-80 Monitor, a File Management program and patched stringy floppy versions of TRS80 I/III classics like Scripsit, EDTASM and Electric Pencil.  These also needed to be transferred from virtual wafer and hence preserved

About a year ago, I had worked through all my stringy floppy wafers.  They were in bad shape, having been stored for decades in a very warm environment.  I had to toss about ½ of them out.  Hopefully though, these classic stringy floppy programs were still on my remaining wafers.

After figuring out a way to transfer the programs to a virtual wafer, I looked through my remaining wafers for the programs above.  Scriptsit, EDTASM and Electric Pencil were long gone.  However, I found the ESF-80 monitor and the File Management Systems and managed to transfer those.   Hooray!  I also found the elusive Data I/O tape, which was the most sought after.  Fantastic!

Photo 3. Stringy Floppy sort-through

I inserted the DATA I/O tape and read it.  It worked!  I then set the system up for recording in readiness to grab the program, which was now sitting in the memory of my TRS-80.  I loaded in my monitor program.  Whoops!  I had picked the wrong version and it overwrote the Data I/O program in RAM.  Oh well, no worries, I’ll just reload it.

I typed @LOAD to reload the program from the wafer.  Capstans turned, lights flashed, motors whirred….and whirred …and whirred..??  What the??  On no, the wafer tape had snapped!

Disaster!  Did I have another copy *frantic searching*?  No.  Bugger!

Photo 4. One snapped Data I/O stringy floppy wafer

I wondered if anyone else out in the vintage TRS80 community had a copy of this necessary stringy floppy program and posted a few notes on the forums.  It didn’t look promising.

There was one other avenue to persue.  I have a friend who used to own a lot of TRS80 gear living locally and in fact, had donated quite a bit of stuff to me.  Maybe he still had some wafers?  I contacted Jeff and yes, he still had his old library (but not a working stringy floppy).

Jeff called around and we found the Data I/O program in his stash.  This time there was no mistakes and the Data I/O file was extracted and saved for posterity.  I’ve added this and the others I found to an stringy floppy archive page on my System 80 site.

Jeff donated me his wafers.  I went through them all and extracted some software, but they were in much the same degraded state as mine.  The cull was large (all the ones seen opposite either snapped or didn't work) so I was left only with a handful which successfully verified. 

In retrospect we were lucky to get the Data I/O program off at all!

So ends my adventures with the stringy floppy.  I still haven’t found stringy floppy patched copies of Scripsit, EDTASM or Electric Pencil so if anyone has copies, send them to me and I’ll add them to the archive.

Tez

18th July, 2009