# RFC ls010 SVP64 Zero-Overhead Loop Prefix Subsystem
+**URLs**:
-TODO template from other RFCs
+* <https://libre-soc.org/openpower/sv/>
+* <https://libre-soc.org/openpower/sv/rfc/ls010/>
+* <https://bugs.libre-soc.org/show_bug.cgi?id=1045>
+* <https://git.openpower.foundation/isa/PowerISA/issues/64>
+
+**Severity**: Major
+
+**Status**: New
+
+**Date**: 04 Apr 2023 v1
+
+**Target**: v3.2B
+
+**Source**: v3.0B
+
+**Books and Section affected**:
+
+```
+ New Book: new Zero-Overhead-Loop
+ New Appendix, Zero-Overhead-Loop
+```
+
+**Summary**
+
+```
+ Adds a Zero-Overhead-Loop Subsystem based on the Cray True-Scalable Vector concept
+ in a RISC-paradigm fashion. Total instructions added is six, plus Prefix format.
+```
+
+**Submitter**: Luke Leighton (Libre-SOC)
+
+**Requester**: Libre-SOC
+
+**Impact on processor**:
+
+```
+ Addition of new "Zero-Overhead-Loop-Control" DSP-style Vector-style
+ subsystem that in simple low-end (Embedded) systems may be minimalistically
+ and easily be implemented by inserting a new fully-independent Pipeline Stage
+ in between Decode and Issue, with very little disruption, and in higher
+ performance pre-existing Multi-Issue Out-of-Order systems seamlessly fits likewise
+ to significantly boost performance.
+```
+
+**Impact on software**:
+
+```
+ Requires support for new instructions in assembler, debuggers, and related tools.
+ Dramatically reduces instructions. Requires introduction of term "High-Level Assembler"
+```
+
+**Keywords**:
+
+```
+ Cray Supercomputing, Vectorisation, Zero-Overhead-Loop-Control (ZOLC),
+ True-Scalable Vectors, Multi-Issue Out-of-Order, Sequential Programming Model,
+ Digital Signal Processing (DSP), High-level Assembler
+```
+
+**Motivation**
+
+SIMD is getting out of control and damaging the reputation of mainstream
+general-purpose ISAs that offer it. A solution from 50 years ago exists
+in the form of Cray-Style True-Scalable Vectors. However the usual way that
+True-Scalable Vector ISAs are done *also* adds more instructions and
+complexifies the ISA. Simple-V takes a step back to a simpler era in
+computing from half a century ago: the Zilog Z80 CPIR and LDIR instructions,
+and the 8086 REP instruction, and brings them forward to Modern-day Computing.
+The result is a huge reduction in programming complexity, and a strong
+base to project the Power ISA back to the most powerful Supercomputing ISA
+for at least the next two decades.
+
+**Notes and Observations**:
+
+1. TODO
+
+**Changes**
+
+Add the following entries to:
+
+* A new "Vector Looping" Book
+* New Vector-Looping Chapters
+* New Vector-Looping Appendices
[[!tag opf_rfc]]