Spectravideo SVI-777
This page was last modified 08:54, 6 July 2022 by Mars2000you. Based on work by Rderooy and Gdx.



The Spectravideo SVI-777 Stringy Floppy Drive is not actually a floppy drive but a special cassette data recorder. Nowadays the cassette tapes for the SVI-777 (Microwafer tapes) are very, very rare.

This device requires a MSX computer with at least 64KB RAM and can't be used on MSX Turbo R.

It needs to be connected to both the data recorder connector and the general port 2. It must be powered by 2, size D, batteries. It can save roughly 14~100 kB per tape, depending on the length of the tape.

The operating system must be loaded before use. It is provided on a Microwafer tape. The steps to load it are as follows:

  • Connect the Stringy Floppy Drive to the data recorder and joystick 2 connectors
  • Turn ON the connected peripheral devices and the MSX
  • Insert the Master Tape into the Stringy Floppy Drive
  • Type: BLOAD"cas:boot",R under Basic (the name "boot" can be omitted) to install the Stringy Operating System (SOS) including a MSX-BASIC extension: see SOS BASIC

The Master Tape also contains:

  • a program to format a new Microwafer tape: SFORMAT.SYS
  • a program to copy files from Microwafer tape or data cassette tape to another Microwafer tape: FILECOPY.SYS
  • several loaders and other files of the Stringy Operating System (SOS)


Spectravideo SVI-777
Spectravideo SVI-777 box
Spectravideo SVI-777 with Master Tape


The Baud rate is 13200 baud.