Bits From my Personal Collection – Space Strike, Space Invaders invading the IBM/PC in 1982


While working on a bigger article on Datamost I thought I’d branch out and focus on one of the more interesting titles, at least from an IBM/PC perspective. Space Strike, a Space Invader clone from 1982 and the first commercial title by one of the most prolific and influential X86 developers, Michael Abrash.

When Taito in June of 1978 released the video arcade game Space Invaders in Japan, it became an instant hit, selling 100.000 arcade cabinets within the first six months of its release. It was quickly licensed in North America by Bally’s Midway division and had a limited release in July of 1978, in October of the same year the arcade game would become widely available.
The game would not only be the first game having enemy targets firing back, having the player avoid incoming fire, it was also the game that popularized the concept of achieving a high score.
Now the game is considered to be one of the most influential games of all time. Not only introducing some of the biggest names in game development to video and computer games but also directly inspiring some of the most iconic titles in computer gaming history.

The initial title was Space Monsters, a title which the artist working on the arcade cabinet graphics, based his artwork upon. Which is why the cabinet doesn’t depict the actual aliens in the game

Space Invaders took the world by storm and is often credited as the title that turned the video arcade game market into a global cultural phenomenon. The game would go on to become one of the most cloned games of all time. Even today, over 40 years later, the game features some of the most iconic and recognizable game imagery.

In the late ’70s when computers slowly turned into devices the ordinary man could approach and be entertained with, it also resulted in space-themed games. While the first widely available computer games were showing up in the wake of the space race giving inspiration to space content, the space-oriented games were just as much a product of the extremely limited capabilities of the early computers. Space being mostly black would leave most of the screen unprocessed, not showing any graphics, leaving just about enough resources for player and enemy movement and simple actions like firing a laser. Also, space ships and aliens could crudely be depicted in the few pixels available, in any artistic form without any reminiscence of what people might perceive as correct or wrong.

When the time came to leave the ’70s behind, the personal computer was still very much a novelty, most owned by hobbyists and enthusiasts. In reality, most computer owners didn’t really know what their computer, besides playing games, could be used for. When IBM released their take on a personal computer in August of 1981 it was announced first and foremost as a business machine. Catering to a new and fast-growing market of spreadsheets and wordprocessors. Probably unexpected to corporate mastodont IBM, games, like with earlier computers, quickly became a dominant factor, not only as software titles aiding and grossing to the machine’s ecosystem but also as technological spearheads pushing the machine and its abilities into undiscovered territories.
Unlike most processors at the time, the x86 Intel 8088 microprocessor IBM had chosen for its PC, had a complex and irregular instruction set. The quirky nature of the x86 meant that programming in assembly language differed fundamentally from other languages, but while undeniably harder to work with, the potential of assembly code was that much greater. The IBM/PC and the X86 processor spawned a new breed of programmers, where some were able to harness and utilize the true potential and performance of the system. One of those was Michael Abrash.

In 1980 while Abrash was a grad student at the University of Pennsylvania, he started to fall in love with the personal computer. At the time Abrash owned a Vector Graphics VIP microcomputer also known as Vector 3. When the IBM/PC was released in August of 1981 Abrash left his Ph.D. to endeavor into the world of software development for IBM’s new platform. His first commercial title was Space Strike, a clone of the hugely successful Space invaders.
With video arcade games having specific purpose-built hardware to accommodate fast-paced visuals and action, it was a proven challenge for any programmer wanting to copy them to the limited and general-purpose personal computers. But copying existing and successful proven games, kept a focus on the technical aspects without having to come up with a good and playable game design at the same time.
In 1982, When Abrash would put his finishing touches on his Space Invader clone, the arcade game he had copied had grossed almost $4 billion. When completed Abrash struck a publishing deal with David Gordon’s computer book and game publishing company Datamost in 1982.

Gordon had a few years earlier, in 1980, sold his company Programma International, the biggest software publisher of the ’70s, to Hayden Book Company. Hayden turned Programma into Hayden Software with Gordon initially staying on as Vice President and General Manager. Gordon’s personality, however, soon clashed with the Hayden executives and was fired in the spring of 1981, from here on he would establish Datamost with a focus on publishing technical writings and Apple II software. Space Strike would become Datamost’s first and one of only a small handful of titles released for the IBM/PC.
Datamost would over the of course of a 4 year period publish games for Bob Bishop, Bob Flanagan, Dan Illowsky, and Chris Oberth, some of the best programmers of the time.

In Space Strike you are the last outpost between Earth and the invading aliens. You’re stationed on a remote asteroid and part of the alien welcoming committee. The aliens believe only a good human is a dead one! And is now coming at you, wave after wave, unleashing bombs, and missiles. You have your laser and your skills, but are they enough to save your home planet?
Just like in Space Invaders you control a small mobile firing platform that can be moved from side to side along the bottom of the screen. battalions of aliens attack from above, sweeping back and forth and slowly descending towards you. Barriers provide cover from incoming fire but are degraded by weapons fire both from above and from below. The level is complete when all the aliens are destroyed, but ends if you get hit by enemy fire or if the aliens reach the bottom of the screen.

Space Strike was written in assembly language and was in 4-color CGA only

Space Strike was indeed arriving late as a Space Invader clone. Numerous iterations for other personal computers and video consoles existed in abundance but it was a first for the IBM/PC. The game looked better than most and played super fast. It featured 7 difficulty levels and had an added feature from its originator, with every 1000 points spawning an extra life, giving you an added incentive. It was reviewed as a must-have game with superior graphics, great animations, and good sound effects. It was well programmed and error-free.

Space Strike would be an IBM/PC exclusive and the only game from Abrash released by Datamost. Abrash would over the next few years keep developing software that would push the X86 architecture. His experience and skills would later get him into technical writings which resulted in numerous books and articles on graphics programming and performance optimization, including Michael Abrash’s Graphics Programming Black Book, Zen of Assembly Language, and Zen of Graphics Programming.

Abrash’s work influenced and helped software designer John Carmack in his development of the Commander Keen, Wolfenstein 3d, and Doom engines, the framework behind some of the most noticeable and successful IBM/PC games in the early ’90s.
Abrash went on to work for Microsoft where he would become the Graphics Device Interface development lead for the first two versions of Windows NT, working on the windows application programming interface.
In 1995 Abrash joined John Carmack at id Software to work on the fundamental graphics and 3D rendering challenges in the Quake engine.
Abrash returned to Microsoft to work on natural language research and later moved on to the Xbox team, where he would work on the first two Xbox video game consoles. He would become the head of research & development at Valve Software, which started its existence by licensing the Quake source code.
Since 2014, Abrash has been leading the Facebook Reality Labs, the division of Facebook researching and developing future VR & AR technologies for use in next-generation Oculus products.

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