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MIDI Interfaces
MIDI (Musical Instrument Digital Interface) is a standard
protocol that allows electronic musical instruments,
computers and other compatible equipment to communicate.
MIDI interfaces enabled the Sinclair ZX Spectrum to exchange
performance and control information with MIDI-compatible
instruments and sound equipment. This page documents MIDI
interfaces designed for, or marketed for use with, the
ZX Spectrum, including their features, original prices and
contemporary references where these can be established.
Features
Original Price
Upstream MIDI Interface
Upstream Computer Systems
Developed by Rupert Goodwins for the electronic music group Mensana, the Upstream MIDI Interface connects the ZX Spectrum to MIDI-compatible musical instruments, allowing the computer to be used for music sequencing and synthesiser control.
The accompanying software, written predominantly in machine code with a BASIC support program, provides a 3,500-note polyphonic sequencer, multitrack operation and the ability to transpose music into any key. It also supports synthesiser patch changing, with sounds capable of being saved and reloaded via MIDI. Musical sequences can be stored on cassette for subsequent playback.
The interface can also operate independently of the Spectrum as a 1-input/3-output MIDI converter. Additional facilities include MIDI Through and synchronisation pulse connections. Its modular design was intended to allow further capabilities to be added without making the original hardware obsolete.
The Upstream system was demonstrated by Mensana on BBC television's Tomorrow's World. The interface was advertised at £139 inclusive 1 2.
The accompanying software, written predominantly in machine code with a BASIC support program, provides a 3,500-note polyphonic sequencer, multitrack operation and the ability to transpose music into any key. It also supports synthesiser patch changing, with sounds capable of being saved and reloaded via MIDI. Musical sequences can be stored on cassette for subsequent playback.
The interface can also operate independently of the Spectrum as a 1-input/3-output MIDI converter. Additional facilities include MIDI Through and synchronisation pulse connections. Its modular design was intended to allow further capabilities to be added without making the original hardware obsolete.
The Upstream system was demonstrated by Mensana on BBC television's Tomorrow's World. The interface was advertised at £139 inclusive 1 2.
£139.00
2
(inclusive)
References
1.
"New ROM antics" - Interview with the rock band Mensana, discussing their use of the Upstream MIDI Interface with the ZX Spectrum, its development by Rupert Goodwins, and the band's appearance on BBC television's *Tomorrow's World*., Sinclair User, No. 26 (May 1984), John Gilbert, p. 104-105
↩
2.
"MIDI INTERFACE FOR ZX SPECTRUM" - Upstream MIDI Interface advertisement., Electronics & Music Maker, No. 3 (May 1984), p. 47
↩
External Links
Mensana – Innovators (Electronic Soundmaker, May 1984)
(Electronic Soundmaker & Computer Music / Joseph Kay)
— Contemporary interview with the electronic music group Mensana, discussing the development and capabilities of the Upstream MIDI Interface by Rupert Goodwins, its use with the ZX Spectrum, and the band's appearance on BBC television's Tomorrow's World.
Mensana – Music Week, February 1984
(Music Week)
— Contemporary report on the electronic music group Mensana, their appearance on BBC television's Tomorrow's World and their plans to record an album using the ZX Spectrum.
Page Revised: 01/11/2026