Bit of DEC Trivia

--- On Wed, 2/23/11, Guy Sotomayor <ggs at shiresoft.com> wrote: Well, assuming that we're talking about the *data* archived from a DecTape as an image (and not, for example, photograph images of the DecTapes themselves...), then the following should be close: According to sources online, a DecTape can hold 144k of data on a PDP-10, using 18 bit words. Assuming here that they're going by the base 10 definition of "K", as most media manufacturers are want to do, then the following must be true: 144,000 * 18 = 2,592,000 bits. This of course, assumes, that the figure of 144k accounts for the error correcting nature of DecTape, and that the actual bit capacity of the spool would therefore be about double - but since only 144k 18bit words are usable from PDP-10, then that's all the data that needs to be stored to image the tape So, then we have to calculate the size of a 1TB hard disk. This, as we know, is once again using the base 10 definition of all units, (also known as HDD maker's "lying gigabytes"): 1TB = 1,000GB = 1,000,000MB = 1,000,000,000KB = 1,000,000,000,000bytes = 8,000,000,000,000 bits. So, 8,000,000,000,000 / 2,592,000 = 3086419.75ish So, I'm going to guess 3,086,419 DecTapes can be completely stored on a 1TB hard disk, assuming no file system. And quite a few more if hard disk manufacturers didn't blatently lie about the capacity of their products. -Ian