[TUHS] core

David Arnold davida at pobox.com
Wed Jun 20 08:55:05 AEST 2018

Does the screen count as I/O?

I’d suggest that it’s just that the balance is (intentionally) quite different.  If you squint right, a GPU could look like a channelized I/O controller. 


> On 20 Jun 2018, at 06:45, Peter Jeremy <peter at rulingia.com> wrote:
>> On 2018-Jun-18 10:25:03 +0100, Tim Bradshaw <tfb at tfeb.org> wrote:
>> Apropos of the 'my iPhone has more power than our System-360/50, but it has nowhere near the sheer I/O throughput of a mainframe' comment: there's obviously no doubt that devices like phones (and laptops, desktops &c) are I/O-starved compared to serious machines, but comparing the performance of an iPhone and a 360/50 seems to be a matter of choosing how fine the dust you want the 360/50 to be ground into should be.
>> The 360/50 could, I think, transfer 4 bytes every 2 microseconds to/from main memory, which is 20Mb/s.  I've just measured my iPhone (6): it can do about 36Mb/s ... over WiFi, backed by a 4G cellular connection
> One way of looking at this actually backs up the claim: An iPhone has maybe
> 3 orders of magnitude more CPU power than a 360/50 but only a couple of
> times the I/O bandwidth.  So it's actually got maybe 2 orders of magnitude
> less relative I/O throughput.
> -- 
> Peter Jeremy

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