Stringy floppy

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An Exatron Stringy Floppy (cover removed) designed for use with the TRS-80 Model 1
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An Exatron Stringy Floppy (cover removed) designed for use with the TRS-80 Model 1

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[edit] Exatron Stringy Floppy

The Exatron Stringy Floppy (or ESF) was a continuous loop tape drive developed by Exatron for use with the Radio Shack TRS-80 microcomputer among others, launched in 1979. The tape cartridge was about the size of a credit card, although about twice as thick. The magnetic tape itself was 1/16-inch wide - string-like.

The tape was wound in an endless loop, in much the same manner as 8-track tapes. Data and programs were stored sequentially on the tape so that data requests had to scan through the tape until the desired data/application was located before being read. As inefficient as this seems, the method was significantly better than manually rewinding the OEM cassette tape, and less expensive than a floppy drive. Due to way the tape was fed back on the reel, Stringy Floppy tapes had a relatively short life expectancy compared to either the 8-track or floppy alternative.

According to Embedded Systems magazine the Exatron Stringy Floppy used Manchester encoding, achieving 14K read-write speeds and the code controlling the device was developed by Li-Chen Wang (who also wrote a Tiny BASIC, the basis for the TRS-80 Model I Level I BASIC.)

In the July 1983 issue of COMPUTE!'s Gazette the ESF for the VIC-20 and the Commodore 64 was reviewed. The April 1983 issue of Creative Computing reviews the Winter CES show where Texas Instruments showed the TI Compact Computer 40 (CC-40) which included an optional peripheral, "a wafertape digital tape drive similar to the Exatron Stringy Floppy ($139)."

Although the Stringy Floppy was about four times faster than the popular cassette drives of the time, the device never became very popular because floppy disks soon filled the data storage needs of personal computers.

[edit] Vaporware Stringy Floppy hardware

In February of 1983 Coleco announced a "Super Game Wafer" wafer tape system for their ColecoVision system. However by October of that year these plans were canceled and still later in 1983 Coleco turned their focus on the Coleco ADAM utilizing a completely different tape system.

The Coleco ADAM-oriented magazine, Expandable Computer News (ECN), features in their May 1987 issue a picture of the ColecoVision Super Game Module containing a wafer tape drive. The premiere issue of ECN in 1984 says Coleco was planning on using the Exatron Stringy Floppy in their announced "super game pack expansion module". However, the ColecoVision FAQ cites a February 1984 Video Games Magazine article stating that the stringy floppy Coleco was considering was a Entrepo floppy wafer system. Regardless of the OEM wafer drive brand, the stringy floppy for the ColecoVision was vaporware. This history does, however, demonstrate that not only was Exatron was involved in wafer tape marketing and development but other hardware manufacturers such as Entrepo were also.

[edit] Sinclair Microdrive

The Sinclair Microdrive, sold as a peripheral for the Sinclair ZX Spectrum and built into the Sinclair QL, was another string floppy-type continuous loop tape drive.

[edit] Other Stringy Floppy systems

Entrepo also made a stringy floppy drive called the Quick Data Drive (QDD). It was designed for use with the Commodore 64 and some Timex Sinclair machines. The same mechanism and cartridges were used in the Rotronics Wafadrive for the ZX Spectrum.

[edit] Emulation

There are no known 8-bit micro emulators that attempt to emulate the accurate functionality of these devices. This may be due to the fact that most stringy floppies typically connected to their micro host systems directly on a hardware bus so to interface and emulate the environment would be a challenge for most programmers. However the firmware code for at least one stringy floppy unit, the ESF for the TRS-80 Model I, has been dumped and source code from Exatron is available online.

[edit] External links


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Linear Helical-Scan
Three Quarter Inch
(~19 mm)

LINCtape (1962) - DECtape (1963)

Sony DIR (19xx) -
Ampex DST (1992)
Half Inch
(12.65 mm)

UNISERVO (1951) - IBM 7 Track (1952) - IBM 9 Track (1964) - IBM 3480 (1984) - DLT (1984) - IBM 3590 (1995) - T9840 (1998) - T9940 (2000) - LTO Ultrium (2000) - T10000 (2006)

Redwood SD-3 (1995) - DTF (19xx) - SAIT (2003)
Eight Millimeter
(8 mm)

Travan (1995) - IBM 3570 MP (1997)

Exabyte (1987) - Mammoth (1994) - AIT (1996) - VXA (1999)
Quarter Inch
(6.35 mm)

QIC (1972) - SLR (1986)
Four Millimeter
(3.8 mm)

DC100 (1976) - DECtapeII (1979)

DDS/DAT (1989)
One Eighth Inch
(3.18 mm)

KC Standard, Compact Cassette (1975) - Datassette (1977)
Stringy
(1.58 - 1.9 mm)

Exatron Stringy Floppy (1979) - ZX Microdrive (1983) - Rotronics Wafadrive (1984)
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