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doc: Update README.

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commit ff31239afafa4f8662fe20003927f4cfd0209124 1 parent 3c4e192
Wolfgang Puffitsch authored
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@@ -2,24 +2,23 @@ Lemberg is a time-predictable VLIW processor optimized for
performance.
Lemberg can execute up to four instructions per cycle in a four-stage
-pipeline. The processor includes four ALUs, a jump- and a memory-unit,
-and optionally also an FPU for single and double precision
-floating-point numbers. Instructions are cached in a method cache, and
-data may be cached in a stack cache, direct-mapped cache or a fully
-associative cache.
+pipeline. The processor includes one to four ALUs, a jump- and a
+memory-unit, and optionally also a floating-point unit for single and
+double precision floating-point numbers. Instructions are cached in a
+method cache, and data may be cached in a stack cache, direct-mapped
+cache or a fully associative cache.
-Lemberg is time-predictable in the sense that the execution time of
-program fragments does not depend on the pipeline state. Variable
-execution times may only arise from memory accesses; therefore, the
-caches have been designed to reduce the overestimation for worst-case
-execution time analysis as much as possible.
+Lemberg is time-predictable in the sense that the worst case execution
+time of program fragments can be computed easily. The caches have been
+designed to reduce the overestimation for worst-case execution time
+analysis as much as possible. Branch prediction is optional and was
+designed with analyzability in mind.
-The processor runs at 66 MHz in an Altera DE2-70 board, where it
-consumes about 54K logic cells and 61KB of on-chip memory, including
-the floating-point unit and caches.
+The processor in its largest configuration runs at 66 MHz on an Altera
+DE2-70 board, where it consumes about 45K logic cells and 62KB of
+on-chip memory, including the floating-point unit and
+caches. Naturally, smaller configurations require fewer resources and
+usually can run at higher clock frequencies.
Along with the hardware implementation come an assembler, a back-end
-for LLVM, and a basic port of the newlib libc implementation. Having
-both a hardware implementation and a tool chain to compile regular C
-programs set Lemberg apart from many other open-source processor
-projects.
+for LLVM, and a basic port of the newlib libc implementation.
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