3 ms·
I'm arguing that these features make no sense _in the old context_ as well. Why waste 1KiB and namelen-100 bytes per file when space is so precious?
by vitiral 3y ago
I'm arguing that these features make no sense _in the old context_ as well. Why waste 1KiB and namelen-100 bytes per file when space is so precious?
- beardyw 3y agoWe used to have files consisting of many multiple tapes. We changed the OS to do dead reckoning on the end of each tape so we could stop well clear of the actual end mark. That way individual tapes could be copied and substituted if needed. Hard to see the reason if you don't just know.
- vitiral 3y agoI don't think I understand but maybe that's the point. Maybe it seems mysterious because there were other requirements at the time which were themselves already mysterious?
- beardyw 3y agoIf you try to copy a tape to a slightly shorter tape you will be out of luck, and only know when it gets there.
- DamonHD 3y agoBecause some tape drives could only read and write whole (512B) blocks, and the way to be relatively sure that you didn't have a new file was to see two blocks of zeros. The Wikipedia item explains this.
- vitiral 3y agoI think I'm confused. You make it sound like the "tape reader" hardware/driver isn't talking to the "file reader" part in software . Didn't the file reader tell the tape reader the size of the file, so it would already know where the end was (how many blocks it should read)?