IBM Confidential: System/360 File Organization [video]

https://www.youtube.com/watch?v=zokKqP0plrM

Comments

haunterMay 27, 2026, 7:15 AM
Passed away in 2012 so he saw the modern internet age

>Pearson LeRoy Wood, 81, passed away April 4, 2012. He was born May 12, 1930 in Detroit, MI. A graduate of Detroit Institute of Technology, Pearson served two years in the US Army. He was employed by IBM for 37 years. He was a member of Resurrection Lutheran Church and also The American Legion, Post 67, in Cary.

>Survivors are his wife, Elaine; two daughters, Diane Post (Barry) of Cary and Susan Scofield (Fred) of Wake Forest; five grandchildren; three great-grandchildren; five sisters and two brothers.

https://www.dignitymemorial.com/obituaries/cary-nc/pearson-w...

haeseongMay 27, 2026, 6:22 AM
The channel program concept described here, where I/O operations are offloaded to a dedicated controller with its own instruction sequence, was a structural ancestor of modern asynchronous I/O and DMA architectures. The System/360 also codified the byte as exactly eight bits, a decision so foundational that it became the silent assumption underlying every computing architecture that followed.
frohMay 27, 2026, 4:59 AM
(1964)

a webcast about the many great benefits of the novel DASD (direct access storage device) over ISAM (index sequential access)

aka disk and tape.

16mm film

Flipchart

impeccable presentation

thx for the time machine :-)

p_lMay 27, 2026, 7:02 AM
ISAM in all important variants pretty much required DASDs, CKDs (Count Key Data) in fact as opposed to FBAs (Fixed Block Access - which act like normal drives people are familiar with)

Tapes don't provide CKD interface and thus do not work with ISAM.

PinusMay 27, 2026, 6:48 AM
The slide transition at 6:16 took me by surprise. =)

Chap needs to have his suit jacket fixed, though... that collar gap!

themafiaMay 27, 2026, 5:37 AM
DASDs supported ISAM.

And they're not strictly just a disk. It's more like a complex multiplexing system for an array of disks. It has interesting capabilities like "channel programs" that persist to this day which allow you to send miniature programs to the disk controller to have it seek out the precise record you're looking for in one of several access modes.

IBM still provides almost the entirety of it's OS documentation online:

https://www.ibm.com/docs/en/zos-basic-skills?topic=set-what-...

cocodillMay 27, 2026, 5:07 AM
Hairstyles used to be better than they are today.
bitwizeMay 27, 2026, 6:20 AM
Great video for the month of "Mayframe"!