The ZX Interface 1, launched in 1983, was a

peripheral A peripheral device, or simply peripheral, is an auxiliary hardware device that a computer uses to transfer information externally. A peripheral is a hardware component that is accessible to and controlled by a computer but is not a core compo ...

from

Sinclair Research Sinclair Research Ltd is a British consumer electronics company founded by Clive Sinclair in Cambridge in the 1970s. In 1980, the company entered the home computer market with the ZX80 at £99.95, at that time the cheapest personal computer ...

for its

ZX Spectrum The ZX Spectrum () is an 8-bit computing, 8-bit home computer developed and marketed by Sinclair Research. One of the most influential computers ever made and one of the all-time bestselling British computers, over five million units were sold. ...

home computer Home computers were a class of microcomputers that entered the market in 1977 and became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a s ...

. Originally intended as a

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of da ...

interface for use in school classrooms, it was revised before launch to also act as the controller for up to eight

ZX Microdrive ZX Microdrive unit The ZX Microdrive is a magnetic-tape data storage system launched in July 1983 by Sinclair Research for its ZX Spectrum home computer. It was proposed as a faster-loading alternative to the cassette and cheaper than a flop ...

high-speed tape-loop cartridge drives. It also included a

DE-9 The D-subminiature or D-sub is a common type of electrical connector. They are named for their characteristic D-shaped metal shield. When they were introduced, D-subs were among the smallest connectors used on computer systems. Description, ...

RS-232 In telecommunications, RS-232 or Recommended Standard 232 is a standard introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such as a compu ...

interface capable of operating at up to 19.2 kbit/s. At hardware level it was fundamentally a voltage adaptor, the serial protocol being implemented in software by

bit-banging Bit banging is a term of art that describes a method of digital data transmission as using general-purpose input/output (GPIO) instead of computer hardware that is intended specifically for data communication. Controlling software is responsib ...

. This led to problems when receiving data, but not when transmitting. A wedge-shaped device fitting underneath the ZX Spectrum, the Interface 1 required two screws to be removed from the underside of the Spectrum, the existing screwholes being used by longer screws running through the ZX Interface 1 to stop it from inadvertently becoming detached. The Interface 1 contained of

ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * ...

comprising the control software for the Microdrives, an RS-232 port and network interface. This extended the error handler in the

Sinclair BASIC Sinclair BASIC is a dialect of the programming language BASIC used in the 8-bit home computers from Sinclair Research, Timex Sinclair and Amstrad. The Sinclair BASIC interpreter was written by Nine Tiles Networks Ltd. Designed to run in on ...

to allow extra keywords to be used. As this became an official standard, other developers quickly used this mechanism to create language extensions to Sinclair BASIC. Two further revisions of the device's firmware were made following launch.Interface 1
Issue 10, December 1984, Your Spectrum 10 These aimed to improve

cartridge formatting and access time, printing functions via the

interface, and other bugs in the firmware held in the device's internal 8K

Machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...

software which used the officially documented entry points ('hook codes') would experience few incompatibility issues; however, programs using non-standard entry points risked incompatibility due to the presence of revised entry points. The same protocol, renamed QLAN, was later used on the

Sinclair QL The Sinclair QL (for ''Quantum Leap'') is a personal computer launched by Sinclair Research in 1984, as an upper-end counterpart to the ZX Spectrum. The QL was the last desktop microcomputer from Sinclair Research aimed at the serious home use ...

. This was intended to be interoperable with ZX Net, but due to timing differences interoperability was found to be problematic. The ZX Interface 1 was incompatible with some later ZX Spectrum models such as the +2A and +3, due to differences in ROM and in the expansion connector. It was therefore impossible to connect and use the Microdrive units with these later models. It did, however, work with the original +2, although the much larger case made the interface an awkward fit.

Network

The device offered two network ports, allowing up to 64 ZX Spectrums to be daisy-chained using network leads up to long. The network, called ZX Net, used a bidirectional wire with a proprietary CSMA-like protocol. Data could be sent or received at either to or from a numbered workstation, or broadcast to all nodes, allowing one machine to act as a server. Station number 0 is used to indicate broadcast. Data is transmitted in packets, each a maximum of 255 bytes long; the packet and the header are protected by a checksum. Character transmission uses 1 start bit, 8 data bits and 1 stop bit (the common 8-N-1 configuration). Main commands: tp://ftp.worldofspectrum.org/pub/sinclair/books/MicrodriveAndInterface1Manual.pdf worldofspectrum.org - Microdrive and Interface 1 manual 1983, file date :FORMAT "n"; :SAVE * "n"; :LOAD * "n"; Select for example 1 as the address of the first computer (station number): :FORMAT "n";1 :SAVE * "n";2 Select 2 for the second computer address: :FORMAT "n";2 :LOAD * "n";1 Which will then transfer the program from "1" to "2". Other commands: :CAT # Lists the file and directory contents of unit # :LOAD * "m";1;"name" # Loads the program "name" from "microdrive" unit 1

References

External links

ntnu.no - Information at Planet Sinclair

* [http://www.dataserve-retro.co.uk/contents/en-uk/d6.html dataserve-retro.co.uk - Sinclair Interface 1 & Microdrive
*
*
- disassembly version 1
*
- disassembly version 1.2
*
www.sinclair.hu - ZX Interface 1/2/Microdrive Service Manual 1985

www.sinclair.hu - ZX Interface 1/Microdrive Manual 1983
{{Sinclair computers and clones Home computer peripherals ZX Spectrum Computer-related introductions in 1983 de:Sinclair ZX Spectrum#ZX Interface 1

Network

See also

References

External links