(no commit message)

diff --git a/openpower/sv/SimpleV_rationale.mdwn b/openpower/sv/SimpleV_rationale.mdwn
index 2fd44b8655a60de69b63678c5a3c0f2724f04691..89ead34078ca1ce6460db4f0865422cf94cba489 100644 (file)
--- a/openpower/sv/SimpleV_rationale.mdwn
+++ b/openpower/sv/SimpleV_rationale.mdwn
@@ -277,7 +277,9 @@ Vector instructions in RISC-V as there are in the RV64GC Scalar base.
 The question then becomes: with all the duplication of arithmetic
 operations just to make the registers scalar or vector, why not
 leverage the *existing* Scalar ISA with some sort of "context"
-or prefix that augments its behaviour? Make "Scalar instruction"
+or prefix that augments its behaviour? Separate out the
+"looping" from "thing being looped on" (the elements),
+make "Scalar instruction"
 synonymous with "Vector Element instruction" and through nothing
 more than contextual
 augmentation the Scalar ISA *becomes* the Vector ISA.
@@ -286,8 +288,11 @@ the Instruction Decode
 phase is greatly simplified, reducing design complexity and leaving
 plenty of headroom for further expansion.
 
+[[!img "svp64-primer/img/power_pipelines.svg" ]]
+
 Remarkably this is not a new idea.  Intel's x86 `REP` instruction
-gives the base concept, but in 1994 it was Peter Hsu, the designer
+gives the base concept, and the Z80 had something similar.
+But in 1994 it was Peter Hsu, the designer
 of the MIPS R8000, who first came up with the idea of Vector-augmented
 prefixing of an existing Scalar ISA.  Relying on a multi-issue Out-of-Order Execution Engine,
 the prefix would mark which of the registers were to be treated as
@@ -298,7 +303,8 @@ jammed multiple scalar operations into the Multi-Issue Execution
 Engine.  The only reason that the team did not take this forward
 into a commercial product
 was because they could not work out how to cleanly do OoO
-multi-issue at the time.
+multi-issue at the time (leveraging Multi-Issue is the most logical
+way to exploit the Vector-Prefix concept)
 
 In its simplest form, then, this "prefixing" idea is a matter
 of: