Feeds

Jim Westwood, home micro revolutionary

We salute Sinclair's chief geek

SANS - Survey on application security programs

Pocket calculators and TVs

Westwood's designs, often under absurdly tight budget restraints, were never text-book, and sometimes radically risky. The notoriously high return rate on Sinclair products was disguised by the fact that many were sold in kit form. But there's no question that in pushing the envelope of how much could be got out of how little, some of the designs were essentially self-destructive.

Sinclair Radionics Cambridge calculator

The Sinclair Cambridge
Source: Vintage Calculators

By the early 1970s "Sinclair" had become a household name, and it was time for a shift from audio. Today, when you can pick one up in Poundland, it's difficult to imagine the impact of "The Executive", a sleek, black, shirt-pocket calculator that could be yours for as little as £79.95 - just a couple of weeks' wages in those days! Only four years earlier, Hewlett-Packard had introduced the first desktop electronic calculator, the HP-9100 for a price that amounted to around £20,000 in today's money.

Once again, Westwood's design was cash-squeezed, but this time there was an even bigger problem. There was a good reason why the Americans and Japanese had so far stayed away from a pocket calculator. The components were particularly power-hungry, dictating a mains connection, or at the very least large batteries.

Sinclair Executive pocket calculator

The Sinclair Executive
Source: Vintage Calculators

The display LEDs alone ate a lot of juice, but there was a standard solution to this. Instead of supplying steady power, you rapidly switched the LEDs on and off. If pulsed at around 60Hz you could save power while relying on human persistence of vision to see the light as continuous.

The trick tickled Westwood's fancy, and he found himself wondering whether it could be extended across the whole device. There was nothing in the specs for the Texas Instruments GLS 1802 calculator chip to suggest this was possible. But, after all, the circuit did include a number of capacitors, components that behave like tiny temporary batteries. Would they be able to sustain power between the pulses reliably enough to ensure there was no data loss?

Sinclair MTV-1 Micro TV

After the calculator, the telly: Sinclair's MTV-1
Source: Retro Thing

Together with Chris Curry, at this stage still a faithful Sinclair acolyte, Westwood ran the tests. The specs said the TI chip needed 350mW of power. And here it was running reliably with a pulsed current at around 20mW. Job done.

Combat fraud and increase customer satisfaction

Next page: Enter the computer

More from The Register

next story
Reg man builds smart home rig, gains SUPREME CONTROL of DOMAIN – Pics
LightwaveRF and Arduino: Bright ideas for dim DIYers
Leaked pics show EMBIGGENED iPhone 6 screen
Fat-fingered fanbois rejoice over Chinternet snaps
Apple patent LOCKS drivers out of their OWN PHONES
I'm sorry Dave, I'm afraid I can't let you text that
Microsoft signs Motorola to Android patent pact – no, not THAT Motorola
The part that Google never got will play ball with Redmond
Slip your finger in this ring and unlock your backdoor, phone, etc
Take a look at this new NFC jewellery – why, what were you thinking of?
Happy 25th birthday, Game Boy!
Monochrome handset ushered in modern mobile gaming era
Rounded corners? Pah! Amazon's '3D phone has eye-tracking tech'
Now THAT'S what we call a proper new feature
US mobile firms cave on kill switch, agree to install anti-theft code
Slow and kludgy rollout will protect corporate profits
prev story

Whitepapers

Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.