Launched in 1981, Sir Clive Sinclair’s ZX81 – successor to his ZX80 released the year before – was designed to be a low-cost introduction to home computing for the general public. It was a hugely successful machine, with over one and a half million ‘official’ units being sold; many more unauthorised ‘clones’ were also produced, particularly in Russia and other Eastern Bloc countries of the era. One could either purchase the machine pre-built, or – as a significant number of consumers did – buy it in kit form for assembly at home at a slightly cheaper price. This ‘DIY’ approach, encouraged by Sinclair Research, became a core element of the computer’s genetic make-up. Those who were comfortable putting together the four silicon chips and other such components were just as keen to poke around the machine’s memory, learning as much as they could about its capability; the programs they would write could easily be shared once saved onto a standard audio cassette.

This book helps the reader truly understand how the ZX81 works, with sections covering everything from the structure of the Z80 microprocessor used in the machine to the computer’s registers, ALU and more.

With an introduction to both binary and hex, Understanding Your ZX81 ROM helped many people get the most out of their machine in the very earliest days of home computing.

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Cutting-edge historians explore ideas, communities, and technologies around modern computing to explore how computers mediate social relations.

Computers have been framed both as a mirror for the human mind and as an irreducible other that humanness is defined against, depending on different historical definitions of “humanness.” They can serve both liberation and control because some people’s freedom has historically been predicated on controlling others. Historians of computing return again and again to these contradictions, as they often reveal deeper structures.

Using twin frameworks of abstraction and embodiment, a reformulation of the old mind-body dichotomy, this anthology examines how social relations are enacted in and through computing. The authors examining “Abstraction” revisit central concepts in computing, including “algorithm,” “program,” “clone,” and “risk.” In doing so, they demonstrate how the meanings of these terms reflect power relations and social identities. The section on “Embodiments” focuses on sensory aspects of using computers as well as the ways in which gender, race, and other identities have shaped the opportunities and embodied experiences of computer workers and users. Offering a rich and diverse set of studies in new areas, the book explores such disparate themes as disability, the influence of the punk movement, working mothers as technical innovators, and gaming behind the Iron Curtain.

Abstractions and Embodiments reimagines computing history by questioning canonical interpretations, foregrounding new actors and contexts, and highlighting neglected aspects of computing as an embodied experience. It makes the profound case that both technology and the body are culturally shaped and that there can be no clear distinction between social, intellectual, and technical aspects of computing.

Contributors: Janet Abbate, Marc Aidinoff, Troy Kaighin Astarte, Ekaterina Babinsteva, André Brock, Maarten Bullynck, Jiahui Chan, Gerardo Con Diaz, Liesbeth De Mol, Stephanie Dick, Kelcey Gibbons, Elyse Graham, Michael J. Halvorson, Mar Hicks, Scott Kushner, Xiaochang Li, Zachary Loeb, Lisa Nakamura, Tiffany Nichols, Laine Nooney, Elizabeth Petrick, Cierra Robson, Hallam Stevens, Jaroslav Švelch

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