On 12/11/17, 7:04 AM, Joe wrote:
The rigid platters of IBM cartridges and packs (the things you see in computer rooms in films) did have brown oxide coatings. The surface of each 12 inch platter side stored a magnificent 2.5MB, or at least the version I used did. It was used in a system with an embedded DG Nova, and a competitive product of the time used the modern 8 inch floppy discs...
The student timeshare systems my high school used (running the McGill University MUSIC operating system) while I was a student there (an IBM 370/135 at the District Office) and shortly after I graduated (an on-site IBM 4341) used Merlin drives.
<https://www-03.ibm.com/ibm/history/exhibits/storage/storage_3330.html> <https://www-03.ibm.com/ibm/history/exhibits/storage/images/overlay/PH3330.jpg> Artist's conception, with a drive open, at <https://en.wikipedia.org/wiki/File:IBM_magnetic_disk_drives_3330%2B3333.png> Typical pack, in pack-cover, at <http://www.computerhistory.org/collections/catalog/102649181>The only time I saw one open was on the 4341 (I was working a summer job at the school), when a power failure caused the emergency retract mechanism to jam, and we had to get a technician out (from CDC!) to unjam the heads.
The 4341, at least, also had an 8" floppy drive, buried inside the CPU cabinet.
-- JHHL