On Wed, 6 Mar 2019 20:18:55 -0800, Charles Mills wrote:
>The 360/40 had one: 7 us for LR, 10 us for L.
>
>It is not possible now. A single instruction may literally add no time at
>all to some instruction sequence.
>
>My imperfect model is that main storage is the new disk. Figure that
>instructions take no time at all and memory accesses take forever.
>
One exception mentioning at least relative speed I find nowadays is:
IBM ® z/Architecture Principles of Operation SA22-7832-10
Chapter 4. Control
Timing
Time-of-Day Clock
TOD Programmable Register
Programming Notes:
...
12. Due to the sequencing rules for the results of STORE CLOCK and
STORE CLOCK EXTENDED, the execution of STORE CLOCK may be
considerably slower than that of STORE CLOCK EXTENDED and STORE
CLOCK FAST. Depending on the model, the relative slowness of
STORE CLOCK (as compared with STORE CLOCK EXTENDED and STORE
CLOCK FAST) is particularly noticeable when multiple STORE
CLOCK instructions are executed within a short period of time.
-- gil
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