Academic workstations -- Followups to comp.unix.questions ONLY

[Alexis Rosen]

Barry Shein posted a message proclaiming the virtues of network servers.
I don't have anything to say pro or con for this position- I'll leave
that to those better qualified. He also stated that the Mac has very
slow disk channel speed, and quoted an average time for small disks of
20KB/sec.

This number is ridiculous. Even the Mac Plus can do better than that.
You'll see about 50KB/sec. with cheap 20-30MB disks. You can do quite a
bit better with the faster ones. But this article wasn't discussing
Mac Pluses, but rather Mac IIs. And the difference between the two is vast.

I have attached to my machine three disks: and old Quantum Q280, a
Wren III half-height (90MB), and a Wren Runner full-height (320MB).
The old Quantum, which has a lousy controller, does about 5Mbit/sec.,
or abuot 625KB/sec. - roughly 31 times faster than Barry's estimate.
The Wrens are much faster. The (also old) Wren III does better than
1MByte/sec., and the Runner (which is the fastest disk 5.25" disk I
know of) consistantly does better than 1.5MBytes/sec, more than 75
times faster than Barry's claim.

For all this, I won't say the Mac has a particularly fast disk
channel. It doesn't, and it has no provision for DMA. Fortunately,
this will be corrected this summer. Apple will likely be introducing a
macine with a faster DMA SCSI controller. Even if it doesn't, though,
for $600 you'll be able to buy a synchronous SCSI DMA board that
should drive disks like the Wrens at about 4MB/sec. (burst, of course,
since disks can't suck up information that quickly off their platters).

---
Alexis Rosen
spector at vx2.gba.nyu.edu (temporary guest account)
alexis at rascal.ics.utexas.edu  (last resort)