| ▲ | froh 2 hours ago | |
(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_l 17 minutes ago | parent | next [-] | |
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. | ||
| ▲ | Pinus 31 minutes ago | parent | prev | next [-] | |
The slide transition at 6:16 took me by surprise. =) Chap needs to have his suit jacket fixed, though... that collar gap! | ||
| ▲ | themafia 2 hours ago | parent | prev [-] | |
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-... | ||