how fast were drum memories?

[Rob Jarratt]

The fixed head disc used on MU5 had a 20.5ms revolution time and an inner
track data rate of 2.2Mbytes/sec.

Regards

Rob 

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Paul
> Koning via cctalk
> Sent: 10 May 2018 17:30
> To: Grif <grif615 at mindspring.com>
> Cc: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: Re: how fast were drum memories?
> 
> 
> 
> > On May 10, 2018, at 10:37 AM, Grif <grif615 at mindspring.com> wrote:
> >
> >
> > I wonder how the late generation paging disks (fixed head per track)
like
> DG used in the 80's compared?
> 
> One that comes to mind is the DEC RS04.  It spins at roughly 3600 rpm (a
hair
> less, so obviously a 2 pole induction motor running off 3-phase 60 Hz
power).
> Transfer rate is 0.5 megabytes per second, but still, at that RPM, average
> latency is 8.5 ms.
> 
> 	paul