Putting It Together
Every good idea was half-executed at MITS.
–Bill Gates, cofounder of Microsoft
Compared with mainframes and minicomputers, the Altair was seriously deficient. It lacked any means of permanent storage. Users could put information into the machine and manipulate it, but once they shut off the power, the information disappeared. Even temporary storage was extremely limited. Although the Altair had a memory board, its 256 bytes of memory wouldn’t have allowed enough space to hold this paragraph.
As an I/O system, the front-panel setup was awkward to use and required a tedious series of steps. To enter information, users had to flip tiny switches on and off; one flip of a switch equaled one bit of information. To read output, a user had to interpret a series of flashing lights. Entering and verifying a paragraph’s worth of information might take several minutes, even with practice. Until paper-tape readers and Gates and Allen’s BASIC came along, Altair owners had to communicate with their machines in machine language bit-by-bit via this switches-and-lights routine.
Machine language was the native language of the Altair’s microprocessor, the Intel 8080. A machine language is a set of commands, in the form of numeric codes, that elicits a response from a computer’s CPU. The code causes the CPU to execute one of its elementary functions—for instance, copying the contents of one specified location in memory onto another location or adding the value of 1 to a stored value. Some programmers, the “true hackers,” preferred to work in machine language because of the intimate and immediate control the language gives them over a CPU’s operation. But all programmers agree that programming in a higher-level language is vastly easier than having to work with machine language. Altair BASIC was a higher-level language. Unfortunately, It took up 4096 bytes of memory. This is remarkably little memory for a high-level language, but it was 16 times the amount of memory that MITS provided in the Altair.
By filling most of the Altair’s 18 slots with 256-byte memory boards and entering Gates and Allen’s BASIC into the system—a tedious process that involved flipping the front-panel switches more than 30,000 times without an error—users could theoretically get a high-level language running. However, the amount of memory left for their own programs would be minuscule. Moreover, the BASIC would have to be reentered every time the machine was turned back on. Two improvements were needed to make the BASIC, and in fact the Altair, useful: higher-capacity memory boards and a method for entering programs quickly. MITS was at work on developing both of these. But MITS was at work on a lot of things.
Getting It to Work
When Paul Allen arrived in Albuquerque, MITS’s biggest hardware project was a 4K memory board that Ed Roberts had designed and technician Pat Godding was attempting to build. In computer jargon, the letter K, short for kilo, represents 1,024, the number closest to 1,000 that is a power of two. Therefore, 4K equals 4,096. Because digital computers use a binary number system, in which every number is expressed as a sum of powers of two, exact powers of two are especially easy for a computer to work with. Computer capacities, such as amount of memory or the largest displayable integer, are generally expressed in powers of two. The new MITS memory board could hold more than 4,000 bytes of information, so Altair BASIC could fit comfortably on it.
Because the 4K memory board would make it possible to run Gates and Allen’s BASIC on the Altair, Allen was particularly concerned that the board should work reliably. It didn’t.
Or rather, it didn’t when combined with other boards. The problem wasn’t just the board itself, but also the performance of two or more boards together. “It was almost analog circuitry,” Allen said. “Things had to be calibrated so exactly.” Bill Yates and the other MITS engineers came to dread Allen’s visits to their work area. In order to test the enhancements he was adding to his BASIC, Allen had to try them out on a working Altair with functioning 4K memory boards.
Unfortunately, none of the 4K memory boards were working. Allen would bring in his latest modification to a program and key it into the machine, whereupon all the panel lights would turn on, the Altair’s way of throwing up its hands in confusion. When technical changes failed to correct the 4K boards, engineers went the redundancy route. At one point, MITS was keeping seven Altairs running constantly just to have three reliable machines at any given time. “That 4K dynamic memory board was atrocious,” Roberts later admitted.
At least Allen didn’t have to key in all of the BASIC every time he wanted to use the machine. The workshop Altair had some secret capabilities that MITS wasn’t yet ready to release to customers. Its programs and data could be stored on paper tape and then loaded back into memory later on. When Allen first demonstrated BASIC to Roberts, he brought it to MITS on paper tape. For a while, paper tape was the major means of distributing the language. Bill Gates would later curse those paper tapes because they provided the medium for widespread illegal copying of their BASIC.
But paper tape had some serious drawbacks as a storage medium for microcomputers. Paper-tape readers and punches were expensive, considerably more expensive than the Altair computer itself. Paper-tape systems were also not terribly fast or efficient.
MITS recognized the need for an inexpensive storage method and was considering using audiocassette recorders. Many computer users already owned cassette-tape recorders, and if a recorder could double as an Altair storage device, all the better. But like paper tape, cassettes were a slow and clumsy way of storing data. By comparison, IBM had long used disk drives for data storage on its large computers. Disks, although expensive, made data storage and retrieval quick and easy.
Roberts was convinced MITS should put disk drives on the Altair. Paul Allen agreed. In 1975, when Bill Gates also made the move to Albuquerque to work on MITS programs, Allen asked him to write the software that would allow the Altair to communicate with a disk drive. But Gates was currently occupied with other tasks, and he put off writing the disk code.
MITS had no shortage of either hardware or software projects. The company was working on interfaces to Teletype machines, printers, and cassette recorders, as well as looking for ways to link a simple terminal to the Altair. MITS was also developing the programs to control these devices, new versions of BASIC and enhancements to the language, and application programs. In addition, all these items needed documentation. On top of all this, MITS undertook PR projects such as a user conference and a newsletter.
Taking It on the Road
One unusual promotional gimmick was the “MITSmobile,” also known as the Blue Goose. An outgrowth of Roberts’s fondness for recreational vehicles, the Blue Goose was an advertising tool designed to spark interest in microcomputing. Gates recalled touring on the Blue Goose: “It was one of those GM motor homes. We’d drive around the nation, and everywhere we’d go, we’d get somebody to start a computer club. I was part of the song-and-dance for one of the tours.” The Blue Goose, like many other MITS innovations, inspired imitators. Utah-based Sphere, one of MITS’s first competitors, soon thereafter sent a Spheremobile roving about the land.
The Blue Goose promotion proved effective. One of the clubs it helped initiate was the Southern California Computer Society, which in turn published an influential early microcomputer magazine, SCCS Interface.
There were good reasons for starting computer clubs. The equipment in these early days didn’t always work or work properly, and software was often unusable or nonexistent. Although buyers were typically engineering hobbyists, few of them had all the skills necessary to fully understand a microcomputer. The clubs encouraged a synergistic sharing of knowledge among the sophisticated-but-stymied users of the machines. Without this interaction and mutual aid, the industry would not have blossomed as it did.
MITS no longer depended on local initiative. By April, MITS had its own nationwide computer club that held design contests and published a newsletter called Computer Notes. David Bunnell started up the publication and Ed Roberts contributed a semiregular column called “Ramblings.” Throughout much of the newsletter’s publication history, Gates and Allen wrote a sizable portion of its contents.
The Altair club offered free membership to Altair owners or those who could pass as owners while they awaited delivery from MITS. Meanwhile, other clubs were springing up that bore no particular allegiance to MITS. The Southern California Computer Society and the Homebrew Computer Club in Northern California, although filled with actual and prospective Altair owners, were also made up of technically sophisticated hobbyists who soon contemplated building computers of their own.
The Homebrew Computer Club members were especially interested in this challenge, and from the club’s ranks there quickly emerged a true competitor to one of MITS’s most important products.