bit addressing, alignment, bus errors, and VM (was Re: PDP-10 arch question)

From: Philip.Belben_at_pgen.com <(Philip.Belben_at_pgen.com)>
Date: Mon Oct 26 07:24:20 1998

> Incidentally, a quick quiz. Assuming all the virtual address space was
> physical memory and you wanted to make a copy onto a disk drive
> (32 Trillion Bytes - we didn't even have GigaBytes back in 1972, let
alone
> TeraBytes), how long would a sustained WRITE at 1 MByte/second take?
> Hint: Answer should be in ONE digit of precision along with a time
interval.
> Eager beavers who want to give us 8 significant figures of precision
> are disqualified.
Just over 1 year
Just under 400 days
Quite a bit under 60 weeks
Just under 13 months ... oops, that was 2 sig. figs. Rather more than 10
months then.

If you want even sillier units, and at the risk of reviving an off-topic
debate, rather more than 30 megaseconds.

Could these disks do a megabyte per second in 1972? Sounds rather fast to
me...

Philip.
Received on Mon Oct 26 1998 - 07:24:20 GMT