MOS Technology 6502meseec.ce.rit.edu/551-projects/spring2016/1-1.pdf · MOS Technology 6502...
Transcript of MOS Technology 6502meseec.ce.rit.edu/551-projects/spring2016/1-1.pdf · MOS Technology 6502...
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MOS Technology 6502Architecture, Design, and Impact
Chris RancTravis Whitaker
Rochester Institute of Technolgoy
Spring 2016
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MOS Technology 6502 Overview
I Released in 1975 in 40-pin DIP package.
I Competed directly with the Intel 8080and Zilog Z80.
I Lead to rapidly decreasing prices in themicroprocessor market.
I Widely popular in personal computerand system integration applications.
I MOS acquired by Commodore in 1976.
I Still used in embedded systems today.
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History
I Chuck Peddle noticed Motorola customers were frustratedwith high 6800 unit cost.
I Proposed a lower area, lower power, lower cost 6800spin-off.
I New design leverages depletion-mode metal oxidesemiconductor transistors.
I Frustrated by Motorola management, Peddle joins MOSTechnology, who fund the 6502.
I 1975 saw a recession impact the silicon industry; 6502 salesflop as a result.
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Beginnings of the Microcomputer
I To bolster sales, Peddle designsthe MDT-650 single-boardcomputer development platform.
I MDT-650 extremely popular withboth engineers and hobbyists.
I Apple, Commodore, Atari, BBCcapitalize on the emerginghobbyist/home computer market.
I Apple II, Commodore PET &VIC-20, BBC Micro, Atari 800 alldesigned around the 6502.
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Specifications
I 3 8-bit General Purpose Registers
I 8-bit Stack Pointer
I 8-bit Status Register
I 16-bit Program Counter
I 1 Edge-Triggered Non-Maskable Interrupt
I 1 Maskable Level-Sensitive Interrupt
I External Memory Address/Data Bus
I RDY output for Hardware Step-Through
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6502 Implementation
I 1-2 MHz typical clockfrequency.
I Two synchronizations percycle.
I Static PLA used forinstruction decoding.
I 2-stage concurrent fetchpipeline.
I 3,510 total transistors.
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6502 Polysilicon Diffusion Layers
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Addressing Modes
I Absolute (ImmediateAddress)
I Branch-relative
I Zero Page
I Absolute/Zero-PageIndirection
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Home Game Consoles Emerge
I Ted Dabney and Nolan Bushnell begin investigatingmicroprocessor-based video games.
I Unlike previous games based on dedicated discrete logic,microprocessor-based systems could play multiple games.
I Dabney and Bushnell realize that such a system wouldcreate it’s own proprietary software market.
I “Stella” prototype adapted to use the low-cost 6502 in1975.
I The Atari Video Computer System (later Atari 2600) wasreleased in 1977.
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6502 in the Japanese Market
I After success in the arcade game market, Nintendo decidesto enter the personal computer market, work on the“Advanced Video System” begins.
I Management decides that the keyboard and terminal willdiscourage non-technophiles from purchasing the system;controllers are the only remaining interface in the finaldesign.
I Engineers design a system around the cost-effective 6502,essentially unknown in Japan at the time.
I Obscurity of the 6502 in the Japanese market led Nintendoto produce it’s own proprietary cross-developmentplatform.
I The “Famicom” is released to critical acclaim in 1983.
I The NES is released in the US in 1985.
I Nintento’s unified development platform and licensingmodel is still used in the console market today.