Java Programming Home Page: Archive: Message #21

Date: Feb 08 2000 11:50:23 EST
From: "Java Programming" <javaProgramming-owner@listbot.com>
Subject: Pico Java

Hi All,
A number of you have written me asking
about PicoJava.
You can read more about it at:
http://www.sun.com/microelectronics/datasheets/picojava-I/index.html


Technical Overview

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*	Instruction Fetch/Cache Unit
*	Integer Execution Unit
*	Floating Point Unit (FPU) 
*	Data Cache Unit
*	Stack Manager Unit
*	Bus Interface Unit
*	Powerdown, Clock, Scan Unit


Instruction Fetch/Cache Unit (ICU)

The Instruction Cache Unit (ICU) fetches instructions from the 
Instruction cache (ICache) and provides them to the decode block 
located in the integer unit. In order to separate the rest of the 
pipeline from the fetch stage, a twelve byte Instruction buffer 
(IBuffer) is used to hold any instructions fetched from memory until 
they are consumed by the integer unit. 
The Instruction cache is a direct-mapped, eight byte line size cache 
with single cycle latency. The cache size is configurable to 0KByte, 
1KByte, 2KByte, 4KByte (default), 8KByte and 16KByte sizes. 

The Pipeline is an artifact of PicoJavas Super-Scalar architecture.
It is like an assembly line, where all the workers depend on the
rate of the slowest worker to manufacture goods.

Regards