On Sat, Jun 16, 2018 at 2:36 AM, Dave Horsfall <dave@horsfall.org> wrote:

> ​...​
>
> Hell, I'll bet that my iPhone has more power than our System-360/50, but
> it has nowhere near the sheer I/O throughput of a mainframe :-)


​I sent Dave's comment to the chief designer of the Model 50 (my friend
Russ Robelen).   His reply is cut/pasted below.  For context he refers to a
ver rare book called: ‘IBM’s 360 and Early 370 Systems’ by Pugh, Johnson &
J.H.Palmer .  A book and other other IBMers like Russ is considered the
biblical text on 360:



As to Dave’s comment: I'll bet that my iPhone has more power than our
System-360/50, but it has nowhere near the sheer I/O throughput of a
mainframe.


The ratio of bits of I/O to CPU MIPS  was very high back in those days,
Particularly for the Model 50 which was considered a ‘Commercial machine’
vs a ‘Scientific machine’.  The machine was doing payroll and inventory
management, high on I/O low on compute.  Much different today even for an
iPhone.  The latest iPhone runs on a ARMv8 derivative of Apple's "Swift" *dual
core *architecture called "Cyclone" and it runs at 1.3 GHz.  The Mod 50 ran
at 2 MHz.  The ARMv8 is a 64 bit machine.  The Mod 50 was a 32 bit machine.
The mod 50 had no cache (memory ran at .5 Mhz).   Depending on what
instruction mix you want to use I would put the iPhone at  conservatively
1,500 times the Mod 50.  I might add, a typical Mod 50 system with I/O sold
for $1M.


On the question of memory cost - this is from the bible on 360 mentioned
earlier.

*For example, the Model 50 main memory with a read-write cycle of 2
microseconds cost .8 cents per bit*.

*Page 194 Chapter 4 ‘IBM’s 360 and Early 370 Systems”*



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