Computer Museum - Sinclair Extras  
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Adding to your computer
Sinclair computers could be enhanced with a variety of add-ons.
The most usual of these would include those on this page.
The most common extra was a joystick to play the huge number of games available.
The Spectrum lacked a joystick port, so an interface was required. The one shown here is by Kempston.
My Cheetah 125+ joystick (shown here) has an additional plug for the Spectrum +2 which did have a port but still needed an adaptor.
Interface 1
This solution allowed joysticks with 9-way Atari plugs to be used. It also has connections for microdrives and a printer.
Attaching an Interface 1 raises the rear of the Spectrum.
To make connection more reliable, it could be screwed onto the Spectrum.
Interface 2
Interface 2 had two joystick ports and a printer port. plus a cartridge port. However, few cartridges were produced, most software remained on cassettes.
Interface 2 could be used with Interface 1 to provide access to microdrives.
ZX Printer
The original Sinclair thermal printer, a must-have for printing out program listings. Mine still works after all these years.
The paper has a metalic surface on black paper. The coating is burned away by an electrical charge leaving the image in black.
A strong smell of burning accompanies the printing. The results are initially good but deteriorate with handling and can fade over time.

The printer is powered from the computer but the original ZX81 power supply was not enough and needed to be upgraded.

Alphacom 32 Printer
An alternative to the ZX printer, this one also prints out program listings on a roll of thermal paper but the paper is more normal, printing is quicker and the print clearer.
With its separate power supply, this printer works with my ZX81s and all of my Spectrums but paper this size is hard to find now.
Most Spectrum software was on cassette tape. Although disc drives were made by other manufacturers, these were quite expensive.
Sinclair's alternative was a continuous-tape drive using removable cartridges. Once formatted, each cartridge held about 85KB.
These tapes were unreliable, stretching over time, and were not widely used.
The QL had two built-in microdrives but tapes formatted for one computer were not compatible with the other.
Rotronics Wafadrive
A third-party offering instead of the Sinclair Microdrive.
The Wafadrive also uses a cartridge (a Wafa) with continuous tape. The cassettes are physically larger than those for the Microdrive and come in a range of nominal capacity from 16KB to 128KB. Operation is faster than cassettes but slower than a Microdrive. However, the Wafadrive has two drives and connects to the computer without an interface, making it a cheaper option. Commands for operating the drives are also simpler.
Although regarded at the time as more reliable than microdrive cartridges, the tape is thin and prone to becoming tangled. The same tapes are used in the Entrepo Quick Data Drive (QDD) available to users of other computers.
The Centronics interface was the most commonly used to connect printers while the RS232 interace was used with printers and modems. The Rotronics Wafadrive was equipped with both connections. It also came with the Softek Spectral Writer word processor installed.
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