Reviving a Computer System of 25 Years ago Symposium at ETH - - PowerPoint PPT Presentation

Reviving a Computer System

• f 25 Years ago

Symposium at ETH 20.2.2014 Niklaus Wirth www.inf.ethz.ch/personal/wirth/ProjectOberon

Programming Languages and Software Systems

• Algol-W (at Stanford U. 1966)
• Pascal (1970) Structured programming
• Modula-2 (1979) Modular programming
• Windows, Menus, Icons (on computer Lilith)
• Oberon (1988) Object-oriented programming
• Oberon System (1990, on computer Ceres)

Personal Computers

• Alto at Xerox PARC (1975)
• Hi-res, memory-mapped display, Mouse
• Processor: TTL, 74S181 ALU (5.9 MHz)
• 64K x 16 bit memory (1K bit chips!)
• 2 MB cartridge disk (DEC)
• 3 MHz Ethernet
• Inaugurates the age of computers
• Interactivity

Xerox Alto (1975)

Lilith (1980)

• Alto with newer technology
• Hi-res display, 640 x 800 pixels
• 3 button mouse
• Processor: 4 AMD 2901 (7 MHz)
• 64K 16 bit word memory
• 10 MB cartridge disk (later 15MB disk)
• 3 MHz Ethernet (1981)
• Central laser printer (Canon LBP-10)
• 500 MB central file server (1982)

Lilith (1980)

Lilith (1982)

Ceres (1985, 1988)

• Commercial microprocessor (NS32x32)
• Hi-res display (1024 x 800 pixels)
• 2 MB memory (Ceres-1), 8 MB (Ceres-2)
• 10 MHz clock (Ceres-1), 25 MHz (C-2)
• 40 MB disk (Ceres-1), 80 MB disk (C-2)
• dual port RAM chips for display
• 233 KHz network (low-cost)

Ceres-1 (1986)

Ceres-3 (1990)

Resurrecting Project Oberon

• Project Oberon (Addison-Wesley, 1992)
• A rare book presenting all details of an

entire operating system and compiler

• Essential for engineering education
• Document of the State-of-the-Art of 1990
• Bring it up to date and publish on Web!
• But …

• NS-processor extinct

– Large chapter on compiler is now irrelevant

• Subject of storage mangement presented

in obscure assembler code for NS processor

• Same for raster operations for displaying

characters and lines

• Chapters on compiler, linking loader,

garbage collection, and raster operations are either outdated or missing

• Yet, most of the book can be retained

Consequences

• Design my own processor: RISC
• Implement this processor (with FPGA)

– Low-cost development board Spartan-3 – board contains 1 MB memory (SRAM) – disk replaced by CD-card (SPI interface)

• Describe complete hardware (in Verilog)
• Rewrite chapters on compiler and linker
• Rewrite chapter on peripheral interfaces
• Describe all in Oberon, no assembler!

RISC (2013)

RISC on Spartan 3 (2013)

The processor RISC

Program counter Instr Reg + 1 Program Memory adr C0

+

decode pcmux

• ff

nxpc IR, cond

Data Register

Bank 16 x 32 Data Memory B C0

• ffset

Shifter

adr

ALU

A imm

+

regmux PC IR

RISC instruction set

0 MOV a, n R.a := n 1 LSL a, b, n R.a := R.b ← n (shift left by n bits) 2 ASR a, b, n R.a := R.b → n (shift right by n bits) 3 ROR a, b, n R.a := R.b rot n (rotate right by n bits) 4 AND a, b, n R.a := R.b & n logical operations 5 ANN a, b, n R.a := R.b & ~n 6 IOR a, b, n R.a := R.b or n 7 XOR a, b, n R.a := R.b xor n 8 ADD a, b, n R.a := R.b + n integer arithmetic 9 SUB a, b, n R.a := R.b – n 10 MUL a, b, n R.a := R.a × n 11 DIV a, b, n R.a := R.b / n 12 FAD a, b, c R.a := R.b + R.c floating-point arithmetic 13 FSB a, b, c R.a := R.b – R.c 14 FML a, b, c R.a := R.a × R.c 15 FDV a, b, c R.a := R.b / R.c

What have I learnt?

• Writing a program is difficult
• Writing a correct program is even more so
• Writing a publishable program is exacting
• Programs are not written. They grow!
• Controlling growth needs much discipline
• Reducing size and complexity is the triumph
• Programs must not be regarded as code for

computers, but as literature for humans