The Memory Index

One can get a grasp of how the prices of various things have changed over the years by comparing average wages with prevailing prices; e.g. the Bread Index. Southern Man will examine here the Memory Index, comparing the cost of computer memory in actual dollars and contrasting that to his income at the time.

Southern Man's first computer was a TRS-80 Model I (it took about half an hour to invert a 25x25 matrix but could beat Southern Man at chess) for which he eventually accumulated pretty much all of the accessories. One of these was the Expansion Port, which included 16K of RAM at a cost of $500 for a cost-per-byte of about $30/KB. His annual income at the time (as a college student) was a few thousand dollars per year. The Model I was eventually replaced by a Model III, which served well into grad school (abeit during the final years mostly serving as a remote terminal to the Physics Department mainframe).

The Model III was supplanted by a Commodore Amiga 1000 - color graphics, multitasking, and the envy of his early-PC-owning friends. One of the accessories was a 256K memory module that costs about $250, for about $1/KB. His income was several thousand dollars per year.

The Amiga gave way to Southern Man's first IBM-compatible PC, which was a 486DX with 4MB of memory and four empty memory sockets. 1 MB memory chips were $40 each for a nice round $40/MB. His annual income in those early years of teaching was about $30K which was supplemented for many years by a sideline of building and selling white-box systems so this fine old 486, although the first of many dozens of PCs to grace Casa Southern Man, remains the only name-brand desktop ever purchased retail at a store.

Today, 4GB memory modules sell for about forty bucks, or about $10/GB, and Southern Man's income is about twice what it was twenty years ago.

A side note is that the cost of a contemporary memory upgrade, regardless of size, has been a hundred bucks or so for about twenty years.

So in the last thirty years, memory price per byte has decreased by over six orders of magnitude (just as predicted by Moore's Law) while Southern Man's income has increased by about one (and since his first full-time job, a doubling time of twenty years). He is not particularly sure just what any of this means, other than that (a) a lot of stuff costs way more than twice what it did twenty years ago and (b) a lot of stuff that Southern Man spends his money on today didn't even exist twenty years ago.