Revamping the board

A glitch in some Issue 1 ULA (Uncommitted Logic Array) chips - basically a mass of logic gates to be used or ignored as the chip customers required - required the addition of a secondary integrated circuit to adjust the ULA's timing signal. That problem was repaired with the release of the Issue 2 motherboard.

Late in 1983, Sinclair introduced the Issue 3 motherboard, once more adjusting the chip layout, this time to reduce the machine's power consumption and eliminate the overheating problems that hit many Issue 1 and 2 Spectrums.

Sinclair advertises the new ZX Spectrum
Click for larger image

But these glitches failed to dent the Spectrum's popularity. Demand surged beyond Sinclair's planned 20,000-units-a-month output, leading to a backlog of 30,000 orders by July 1982, a month after the Spectrum began to ship, itself a month and a half after the machine's launch.

That month, the UK government included the 48KB Spectrum on a list of computers approved for secondary school use - the others were the BBC Model B and the Research Machines BBC-esque 480Z - with grants to enable them to buy the machines.

Through the Summer of 1982, thanks to a holiday at contract manufacturer Timex's Dundee plant, where the Spectrum was being assembled, the backlog grew to 40,000 units.

The Sinclair Microdrive and catridge: arrived too late - and didn't work so well when it did

Maybe education viewed the Spectrum as too entertainment-oriented, or perhaps the order backlog simply prevented schools getting hold of all the machines they would like. Either way, Sinclair never made much of a dent on the education market, eventually drumming up a tiny, two per cent share.

Public apology

To calm ordinary punters' fevered brows, Clive Sinclair issued a public apology in September 1982 and gave waiting buyers the opportunity to get their money back. Those who took him up on the offer may well have gone for a ZX81, now selling for just under £50, as a stopgap.

By the time Sinclair had upped production, probably with the arrival of the less costly Issue 2 motherboard, some 60,000 Spectrums had shipped. A further 500,000 Issue 2 machines would ship through the remainder of 1982 and well into 1983, the vast majority of them sold direct by Sinclair itself, some 200,000 by the end of March 1983. Issue 3 added a further three million units to the overall total, though by now High Street shops like WH Smith, Boots, Currys and John Menzies were selling the Spectrum too.

QL-style Speccy: the Spectrum+
Source: Wikimedia

For the year to 31 March 1983, Sinclair announced sales totalling £54.53m, earning it £13.8m in profit.

In May 1983, Sinclair cut the price of the 16KB Spectrum to £99.95 and the 48KB model to £129.95. In July, Timex began selling an own-brand version of the Spectrum in the US, the TS-1500, licensed from Sinclair. In November, it released the Timex TS-2068, with a completely new case design. But sales proved poor and the company collapsed in 1984.

Next page: Mined out