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:
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 :-)
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-...