The Continuity Guide
Computer Print-outs
by Martin Willey

In the early 1970s, computer printing mostly used line printers (which type with a hammer, like a traditional typewriter), using continuous fan-fold sheets of paper, often with green bars, either 80 characters or 132 characters wide. The older teletype printers were still in use for input/output, although punched cards were the principal input method until video screens appeared in the late 1970s. Another new type of impact printer, the dot matrix, also appeared, and while it was slower and poorer quality, it could print non-character symbols and images. Laser printers were invented in 1971, and by the late 1970s began to be used in large data centres for high volume, high quality printing. The technology didn't reach the office market until the HP LaserJet in 1984.

On Moonbase Alpha, computer output is printed on narrow continuous rolls of white paper. The poor quality type indicates it is probably an early dot matrix, the sort used for cash register receipts or one of the early electronic calculators. The first office calculators had printers rather than screens (like the Olivetti Divisumma 18, produced in 1972 and featured in Testament of Arkadia).

The print contains numbers and text with no spaces or empty lines. There are no words within the dense text. It looks like a condensed hex dump, although there are non-hexadecimal characters (which should be base16, 0-9, A-F). In Matter of Life and Death, coloured tape is added to make the receipts more visually interesting. In Space Brain, the paper has abstract symbols.

The paper is printed from one panel on the computer wall of Main Mission, from under the Big Screen at the front of Main Mission (either the same panel as before, or the clock panel), from Kano's desk, and in Dragon's Domain from a communications post.

We don't see the cash register receipts in Year 2. From The Exiles, Moonbase Alpha has adopted the IBM 80-column punch card, introduced by IBM in 1928. You can see the punched holes in the cards when the read the cards. Punch cards were still widely used for data storage and data entry in the 1970s, but their days were numbered. Magnetic tape (seen in UFO and on the Ultra Probe in Dragon's Domain) was the primary method of data storage. Data entry through teletype machines was slow until video terminals were introduced, particularly the DEC VT100 in 1978, making punch cards obsolete by the mid-1980s. Weirdly, while punch cards are a method of input to the computer, the Moonbase computer prints punch cards for humans to read.