Lex Bailey's Luggable Laptop Is Powered by a Sinclair ZX Spectrum — and Boasts Its Own Phone

With an integrated modem and 3D-printed telephone handset, this eight-bit behemoth is heading to Electromagnetic Field 2024.

Gareth Halfacree
1 month agoRetro Tech / 3D Printing / HW101

Maker and PhD student Lex Bailey has built a laptop that's powered by a Sinclair ZX Spectrum microcomputer, complete with tape drive for storage and a working telephone for voice and data calls.

"[I] finished building my ZX Spectrum laptop ready to take to [Electromagnetic Field] 2024," Bailey writes of the luggable device — fitted with a rainbow guitar strap to enhance its portability for the event, known as EMF Camp, which gathers hackers, artists, makers, and tinkerers in tents in a literal field. "It has a Prism modem for Viewdata services, and should hopefully connect to the DECT network [at the event]."

The Sinclair ZX Spectrum launched in 1982 as an affordable eight-bit home computer built around the popular Zilog Z80 processor — since, sadly, discontinued in standalone CPU form, through potentially set for an open-hardware revival. With a color video output and up to 48kB of memory in its initial form, the device proved popular among programmers and gamers alike — despite its rubbery keyboard, semi-affectionately referred to as "dead flesh" by its users.

It's an original ZX Spectrum, complete with that iconic keyboard, which forms the heart of Bailey's build — with as little modern hardware added as possible. The most modern is a color LCD display, which accepts a composite video input from the Spectrum — in place of the stock RF modulator, which would require a display device with an analog TV tuner. To the left of the Spectrum is an original cassette deck, for saving and loading programs.

To the right is something unexpected: a telephone handset and number pad. "I took apart a cheap landline phone and reconfigured it a little," Bailey explains. "The keypad is fully custom, the handset is 3D printed and contains the mic and receiver from the phone I took apart. The [original Prism] modem connects to the phone system via DECT, and the phone is connected to the modem so that it can do the dialing — the modem can't dial by itself."

The project wasn't always straightforward. The display seen in the finished device is the fourth to have been purchased for the project, the other three having been dead-on-arrival. Getting the modem and handset talking to a DECT phone system also took a little trickery, involving the use of a BT Digital Voice Adapter designed for those moved off Plain Old Telephone Service (POTS) connections to modern IP-based exchanges but who still want to use their existing analog phone hardware.

Those attending Electromagnetic Field between May 30th and June 2nd inclusive will be able to see Bailey's creation in action, while more information is available on the project's Mastodon thread; Bailey is planning a video or project write-up to follow, with additional details on the build.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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