A Trip Down (Core) Memory Lane Quiz

Even if you have never used a physical floppy disk - their use sharply declined by the late 1990s due to the advent of affordable CD writers and the internet - you probably know the look of one from the "Save" icon in many applications. A typical 3 1/2 inch floppy disk like the ones depicted held 1.44 megabytes of data - just about enough for the text and the ten pictures involved in this quiz. Windows 95, the last PC operating system to be released on this media type, shipped on 13 or 26 such disks. Due to their slow speed and low capacity, floppy disks were not a practical backup medium.

You will likely be used to Ethernet cables having the phone-like rectangular plug, but in the early years of local networks - up to the 1990s - coaxial cable similar to aerial cables were the standard. These cables were inflexible, and broke easily, but they allowed the creation of branches in the network simply by using a Y-shaped adapter. One common source of error with these cables was that every endpoint needed to be capped - terminated - with a special resistor. Missing a terminator caused transmission errors and low speeds. Locating the one that had fallen off in a large office was a time-consuming task!

This component belongs to an early Commodore 64 home computer from the year 1982. At that time, specialized computer screens were very uncommon and expensive, so most users just connected their television through an analog aerial cable, thus a converter to create an NTSC (or, in Europe, PAL or SECAM) aerial signal from the digital data was needed inside the computer.

Most home computers and early game consoles like the Atari 2600 either used channel 3 VHF or channel 40 UHF, often causing bad image quality from interference if the channel or a neighboring one were actually in use for broadcasting television - not that the quality of these converters was that good even under best circumstances.

Up to the 1980s, telephone companies in almost all countries held a monopoly, not only on the lines themselves, but also on the equipment that was allowed to be used on them. As such, users could only access phone lines through the standard telephones (and later fax machines) rented or bought from the carrier. When you wanted to connect computers with each other, the only way to do so was thus to use an acoustic coupler - a device that would play sounds into the microphone of the handset and, on the other end, record everything that came from the handset's speaker. Two tones - a high and a low pitch - were used to represent a digital 1 and 0 and played for a fraction of a second for each bit.

One can imagine these connections were anything but fast. In fact, the upper limit for these was around 300 bits per second - the equivalent of about 50 letters of text. A more typical speed in practice, however, was one third of that.

The hard disk shown in this picture is an early 1990s IBM mainframe hard disk with just under 2 GBytes of storage space (that's far less than the main memory of a modern smartphone). This was one of the later generations of specialized mainframe computer disk - small and cheap 3.5 inch consumer and small server disks were quickly catching up in capacity and reliability and by the end of the 1990s, these big drives were replaced by RAID arrays (Redundant Array of Inexpensive Disks) to provide high reliability, high capacity storage with a much smaller footprint and power consumption while being cheaper to procure and easier to maintain.

Hard drives are much more expensive per amount of storage than tapes even though high volume tape drives are expensive by themselves. In addition, long time storage of inactive hard drives has a much higher failure rate and requires a much better controlled environment than tapes, thus for backups - especially those stored off site and too sensitive and/or too large to send to a cloud storage over the internet - tapes are still the medium of choice.

The picture shows an IBM 3745 controller and associated tapes - a relatively modern device in the context of this quiz as the last units were made in 2002.

Punched cards were used as the primary input device in times before computers were powerful enough to support multiple users and terminals. While the early operator consoles consisting of simple switches and lights were quickly replaced by a keyboard and screen, directly interacting with the computer was only allowed to trained system operators.

Programmers wrote their code by punching each line into a card (there were special card-punching typewriters available for this purpose) and then stacking those cards in the proper order. This stack was then either read directly into the computer for execution or first transferred to a data tape (especially for programs needed often - card reading was much slower than tape).

Card punchers were also used controlled by the computer for some output, especially for data sets meant to be processed again later.

The picture shows the control console of the UNIVAC I mainframe computer of 1951, which predicted the outcome of the 1952 US Presidential election far more accurately than most polls. At that time, machines could only run a single program at a time and operators had the option of literally stopping and modifying the processing at any time - they could freeze the machine's state, change a register's contents or execute code step by step with actual hardware controls, much like a debugger of modern times. Most early UNIVACs went to the US government, but from 1954 onwards, a few machines were also shipped to private companies such as General Electric and Metropolitan Life.

This is a piece of the main memory from a Control Data CDC 7600, a supercomputer of the early 1970s. The machine could execute about 10 million instructions per second on floating-point numbers. However, its main memory was rather limited: 65000 words of 60 bits each (roughly 500 kByte). Each bit was stored magnetically in a small ring through which three wires had to be threaded - two formed the column and row address, the third, threaded diagonally, carried the data. Reading a value destroyed the information, so it had to rewritten afterwards.

This board comes from an IBM 701, one of the first commercially successful computers released in the year 1952. It is part of the main processor assembly which consisted of just over 1000 vacuum tubes - the predecessors of transistors. The system could add two 36-bit numbers (approximately 10 decimal digits) in 60 microseconds - about 16,000 additions per second. If you wanted to rather multiply, you'd have had to be content with 2,000 calculations each second - from the whole processor, not this one board. Technology has definitely improved over those last 70 years between the IBM 701 and me writing this quiz!