On 6/27/06, deeb <[EMAIL PROTECTED]> wrote:
----- Original Message ----- From: "James G. Sack (jim)" <[EMAIL PROTECTED]> To: "Main Discussion List for KPLUG" <kplug-list@kernel-panic.org> Sent: Tuesday, June 27, 2006 11:28 AM Subject: Re: old terms still familiar today (Was:top/bottom posting...) > deeb wrote: >> >>> >> We had a 2 meg (!) drum drive for use as a aid to doing CTD casts ( >> Conductivity, Temp and Depth.) >> >> It was a sealed unit driven by a 1850 rpm A/c motor.and it had a Rhodium >> plated drum >> It was mounted on the second deck in a dry airconditioned lab space. >> >> Unfortunately the motor acted a a sort of gyroscope and wiped the >> read/write heads out in a short period of time. >> >> The drive cost about $8 K (1972) and was deemed SOTA. >> >> Repair estimate was 3-4 K so we never got any use from it ! > > Hi dee- > > Do you remember how many tracks? Or anything about the head mechanisms? > Oh .. sealed, eh? No inspection windows? > > For the benefit of innocent bystanders, a drum would have as many heads > as there were tracks, so there was no "seeking", no seek latency. Izzat > right? Sorta like a edison wax recordings with multiple pickups. Ohh, > nobody remembers those either? (Well, actually, neither do I, but I > remember pictures of them.) > > Can you explain the "gyroscope-effect" damage. I don't follow. > > ..jim > > The bearings on the unit were not robust. The motion of the ship from > wave action would normally not bother it but we took some severe pounding > both verically and sideways. The bearings started grinding and the drum > actully hit the heads. The were no inspection ports. Don't know about track #'s This item is probably too ancient to search !
Seems to me that SIO shipboard computer group had drum storage for the seagoing IBM 1800's. As a bystander I don't remember any particular trouble over a period of several years. I believe the drum was made by Datum, and had a storage capacity of 512kB or possibly twice that. The San Diego Computer museum, sometimes associated with Coleman College, had a drum like this on display when they were in downtown SD. I don't think anyone there really knew what it was. With regard to "tub memory" I think the reference goes back to when punched cards were filed in circular tubs for ready access by human operators. A Univac document from 1951 discusses this: < http://makeashorterlink.com/?R5241265D > "Because of the high-speed random access, no sorting, merging, collating, reproducing, or pulling of cards from a tub file is required before the processing can begin." With regard to columns 73-80 of an 80-column IBM card, the first high-speed card reader that was developed by IBM was for the purpose of loading data into a 72-bit wide memory. It read the cards by rows. Later the same reader was used on the computers for which Fortran was developed, loading their 36-bit words two at a time. Thus the last 8 columns of the card were inaccessible to the reader. With regard to sequence numbers on binary decks, it was my experience that each card was self-contained, having a start address and then data to be loaded in consecutive locations. So getting the binary deck out of order was not fatal. And if necessary it could be sorted on the address field. The worst thing would be to lose one card from the binary deck, thus resulting in an area of memory that did not get loaded. End of miscellaneous history ramblings for today. carl -- carl lowenstein marine physical lab u.c. san diego [EMAIL PROTECTED] -- KPLUG-List@kernel-panic.org http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
