Nagered hard drive;'(..
in [Computer]
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From: Bob Eager on 25 Jun 2010 02:36 On Fri, 25 Jun 2010 07:12:09 +0100, Roland Perry wrote: > In mid 70's I worked on ICL drives, including something they called a > "drum", which was a single-platter mounted vertically. The important point about the ICL drum was that (like the real drums before it) it had one head for each track, thereby reducing the seek time to the electronic switching time. They were mainly used for paging, but I seem to recall that the ICL ones were let down by a sluggish transfer rate. > My first programming (around 1968) was done on hand-punched cards, which > I preferred to paper tape as it was both easier to edit and faster to > create (I could hand-punch cards faster than the CPS of the teletype > you'd use to make the paper tape). Same here....my first three years (1970-73) were nearly all on punched cards. I still have a few as bookmarks! -- Use the BIG mirror service in the UK: http://www.mirrorservice.org *lightning protection* - a w_tom conductor
From: dennis on 25 Jun 2010 02:57 "Roland Perry" <roland(a)perry.co.uk> wrote in message news:xiItDKI5iEJMFA2Y(a)perry.co.uk... > Somewhere I have an early "PROM", you programmed it by soldering diodes > in, and the foot-square PCB probably has a couple of dozen bytes capacity. I had a piece of PROM where you sewed wires through the ferrite rings to program it. I lost it years ago which is a shame as people couldn't believe it was a bit of computer.
From: dennis on 25 Jun 2010 03:04 "Bob Eager" <rde42(a)spamcop.net> wrote in message news:88j13sFan9U1(a)mid.individual.net... > On Fri, 25 Jun 2010 07:12:09 +0100, Roland Perry wrote: > >> In mid 70's I worked on ICL drives, including something they called a >> "drum", which was a single-platter mounted vertically. > > The important point about the ICL drum was that (like the real drums > before it) it had one head for each track, thereby reducing the seek time > to the electronic switching time. They were mainly used for paging, but I > seem to recall that the ICL ones were let down by a sluggish transfer > rate. Real drums didn't use Winchester type heads IIRC. They were drums so all the heads were the same and the surface speed was the same, with disks the surface speed changes with the head position. > >> My first programming (around 1968) was done on hand-punched cards, which >> I preferred to paper tape as it was both easier to edit and faster to >> create (I could hand-punch cards faster than the CPS of the teletype >> you'd use to make the paper tape). > > Same here....my first three years (1970-73) were nearly all on punched > cards. I still have a few as bookmarks! I learnt Fortran IV using a portapunch to make cards. They were then sent to IC to be run in the batch system by post. When they returned you had to debug them from the printout. It could take a while. That was a primary school, I lost the facility when I went to secondary school as they didn't see computers as important. 8-(
From: Roland Perry on 25 Jun 2010 02:34 In message <kLadnTeW2aZIfb7RnZ2dnUVZ8rednZ2d(a)brightview.co.uk>, at 23:48:40 on Thu, 24 Jun 2010, John Rumm <see.my.signature(a)nowhere.null> remarked: >> RLL Compression? Pray tell me more. > >Run length limiting. Using a RLL controller gained an extra 50% >capacity, but at the expense of a reduced signal to noise and grater >risk of unrecoverable read error. Other way round, surely? It was a coding method to make sure you never had too many of the same polarity bits "in a row", which risks unreadability. What makes a magnetic storage medium work is *changes* in polarity. -- Roland Perry
From: Roland Perry on 25 Jun 2010 02:28
In message <5b2dnXjjK-cQ6r7RnZ2dnUVZ8vGdnZ2d(a)brightview.co.uk>, at 16:19:28 on Thu, 24 Jun 2010, John Rumm <see.my.signature(a)nowhere.null> remarked: >IIRC I bought my first HDD about '87. A "huge" 42MB seagate. By around 1981 I was the UK distributor for the Micropolis range of drives, which were originally in the same form factor as an 8" floppy drive. The most capacious was 33MB, and cost about the same a small family car. One of my customers was the BBC newsroom, who bought one to store digitised images to project behind the newsreader's head - to replace the infamously unreliable slide projector they used to have. In those days it was difficult to find people who thought they needed that much storage (outside of a classic mainframe scenario). -- Roland Perry |