ZX Spectrum+
Introduction
In October 1984, Sinclair Research introduced the ZX Spectrum+, an updated version of the hugely successful 48K ZX Spectrum. Although it looked substantially different from the original machine, the changes were primarily concerned with the case and keyboard rather than the computer's internal hardware.
The launch came as something of a surprise. Rumours of a new Spectrum with a conventional keyboard had circulated for months, but Sinclair Research had repeatedly denied that such a machine was being developed. When the ZX Spectrum+ finally appeared, it brought the Spectrum's familiar electronics into a new case styled along similar lines to the QL.
The result was a machine that looked considerably more substantial than the original ZX Spectrum, while remaining fundamentally the same computer underneath.
The new case
The ZX Spectrum+ retained the basic design and electronics of the 48K Spectrum, but the distinctive wedge-shaped case was replaced by a larger, more angular enclosure. Measuring approximately 320 mm × 140 mm × 40 mm, it was considerably longer than the original machine.
The new case was finished in black ribbed plastic and incorporated two folding feet underneath. When extended, these raised the rear of the keyboard to provide a more conventional typing angle. When folded away, the machine could sit flat on the desk.
A reset button was also fitted to the left-hand side of the case. This was a welcome addition for Spectrum owners, as resetting the computer no longer required the power supply to be disconnected and reconnected. There was still no conventional on/off switch, however.
The new keyboard
The most significant change was the keyboard.
Instead of the small rubber keypads of the original ZX Spectrum, the ZX Spectrum+ used hard, moulded plastic keycaps arranged in a much more conventional layout. There were 58 keys in total, including 17 new keys.
Despite the appearance of a conventional keyboard, Sinclair retained the Spectrum's existing membrane-based switching system. The flexible plastic membrane remained beneath the keys, with the new hard moulded keycaps providing a more substantial and familiar typing experience.
The keyboard included a proper space bar, separate cursor controls and dedicated keys for several commands and functions that had previously required combinations of SHIFT keys.
Dedicated keys were provided for:
CAPS LOCK, DELETE, EDIT, BREAK, TRUE VIDEO, INVERSE VIDEO, GRAPHICS and EXTENDED MODE.
There were also separate keys for punctuation such as the comma, full stop, semicolon and inverted comma.
Two CAPS SHIFT keys and two SYMBOL SHIFT keys were provided, making frequently used combinations easier to reach.
For programmers, the new keyboard offered one particularly useful improvement: several functions which had previously required multi-key combinations could now be entered with a single key press. Graphics and extended-mode commands were especially convenient.
The keyboard was not universally praised, however. The key spacing was relatively compact and the layout had some unusual decisions, while the removal of the original colour-coded legends made the different keyboard modes less immediately obvious.
The keys themselves were double-injection moulded, with the legends formed into the keycaps rather than simply printed on the surface. Sinclair stated that this would prevent the markings from wearing away with use.
Compatibility
One of the most important features of the ZX Spectrum+ was that it remained compatible with the existing Spectrum software library.
The computer used the same basic hardware and ROM as the 48K ZX Spectrum, meaning that existing programs could continue to be used without modification. The same principle applied to many existing peripherals.
This was important at a time when the Spectrum already had a huge library of commercial and user-written software. A new machine that required a completely new software library would have been considerably harder to sell.
There were, however, some practical problems caused by the new case. Certain peripherals designed to plug directly into the edge connector could no longer be fitted because the sides and rear of the new case obstructed their connectors. This meant that some existing accessories required modification or a suitable extension.
The User Guide
The ZX Spectrum+ was supplied with a completely new User Guide, written by Neil Ardley and published by Dorling Kindersley.
It was very different from the original ZX Spectrum documentation. Rather than concentrating primarily on providing a comprehensive programming reference, the new guide used photographs, diagrams, illustrations and colour-coded sections to make the computer appear more approachable to newcomers.
The opening section, Get Going, concentrated on setting up the computer and solving common problems. Later sections introduced programming, graphics and sound, followed by an explanation of the computer's hardware and a reference to the BASIC commands.
The guide was attractive and easy to follow, but contemporary reviewers pointed out that it was considerably less comprehensive than the original ZX Spectrum manual. Important subjects were covered only briefly, and experienced users were likely to find the older manual a more useful reference.
Dorling Kindersley also planned to sell the guide separately, allowing it to be purchased by existing Spectrum owners.
The Companion Cassette
The new User Guide was accompanied by a Companion Cassette intended to introduce owners to the new keyboard and the capabilities of the machine.
The cassette included a keyboard tutorial along with games and demonstration programs. It provided an immediate way for a new owner to experiment with the computer rather than relying solely on the printed instructions.
This combination of a highly illustrated guide and demonstration software reflected Sinclair's attempt to make the Spectrum more approachable to people who might previously have regarded computers as complicated or difficult to use.
The official £20 upgrade
Sinclair Research also offered existing 48K Spectrum owners a way of obtaining the new keyboard without buying another computer.
The official Spectrum Upgrade Kit was advertised at £20 and allowed a working 48K Spectrum to be converted into a ZX Spectrum+. The conversion required several wires to be soldered, with instructions supplied in the kit.
For owners who did not want to carry out the modification themselves, Sinclair offered an upgrade service for £30. Owners could return their 48K Spectrum to Sinclair Research, which would carry out the conversion and return the upgraded machine.
Both options included the new User Guide and Companion Cassette.
The official upgrade was significant because it demonstrated that Sinclair regarded the ZX Spectrum+ primarily as an evolution of the existing 48K machine rather than a completely new computer.
A change of emphasis
The ZX Spectrum+ was therefore an unusual upgrade.
Internally, it remained almost exactly the same computer that had been introduced several years earlier. The processor, memory capacity and BASIC environment were essentially unchanged, while the new case and keyboard addressed some of the criticisms that had increasingly been levelled at the original design.
For programmers, the dedicated keys and more conventional layout could make entering programs considerably easier. For users interested in word processing and other applications requiring extended typing, the hard plastic keyboard was a significant improvement.
For games players, however, the advantages were less obvious. The original Spectrum was already capable of running the same games, and many owners would have been perfectly happy with the rubber keyboard, particularly when using a joystick.
Contemporary reviewers consequently viewed the ZX Spectrum+ with mixed feelings. It was a better-looking and more practical version of the Spectrum, but it did not represent a major technical advance.
The market had also produced a substantial range of replacement keyboards for the original ZX Spectrum. Companies such as Saga, DK'tronics, Transform and Fuller offered larger and more conventional keyboards, demonstrating that there was already a demand for a more comfortable typing experience.
The ZX Spectrum+ 128K
The decision to retain compatibility would prove particularly important when Sinclair introduced the ZX Spectrum+ 128K. The 128K machine added substantially more memory, a new sound chip and an extended BASIC environment, but retained a compatibility mode for existing Spectrum software.
The ZX Spectrum+ was therefore an important stage in the development of the Spectrum range. Although the underlying computer remained largely unchanged, the new keyboard and case gave Sinclair's most successful home computer a more conventional appearance and helped extend its life into the second half of the 1980s.
Technical specification
| Processor | Zilog Z80A at 3.5 MHz |
|---|---|
| RAM | 48K |
| ROM | 16K |
| Keyboard | 58-key full-size keyboard with dedicated function keys |
| Display | Colour television or compatible display |
| Sound | Internal speaker |
| Storage | External cassette recorder |
| Expansion | ZX Spectrum edge connector |
Summary
The ZX Spectrum+ was not a new computer in the same sense as the later ZX Spectrum+ 128K. Instead, it was a carefully packaged development of the existing 48K ZX Spectrum, addressing some of the criticisms of the original machine while preserving its software and hardware compatibility.
Its redesigned keyboard, improved case, reset button and new documentation made the ZX Spectrum more approachable to new users, while the enormous existing software library ensured that the machine remained firmly connected to the established Spectrum user base.