> I am not having a problem at all with how things are done. I was just > curious about why the original developers made "DASD management" such a > burden on the sysprog. Especially in the early days. But performance > could very well be the reason.
1) Back then, there *wasn't* much DASD to manage. VM systems have historically been smaller and lighter, and been relatively resource-poor compared to their OS-based siblings. Consider the original purpose of VM was to be a *migration aid* from OS/360 to later releases; it wasn't intended to be a permanent thing (at least not until real customers got their hands on it) so there wouldn't have been a lot of "VM" disk to manage. 2) Same with memory. Building a in-core table for all the possible minidisks would have been prohibitively expensive on a 2M machine (if I remember correctly, CP-67 would run on even smaller systems than that). The disk-based approach could handle small-memory machines and bigger ones with roughly equal performance.
