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Some thoughts on the 6502 Technology

August 21, 2010 Leave a comment

For text in full-length, see http://www.6502.buss.hk/6502

6502, why it is so important?

The first 6502 microprocessor was designed by Chuck Peddle and Bill Mensch in 1975 for MOS Technology, also known as CSG (Commodore Semiconductor Group), was a semiconductor design and fabrication company based in United States. 6502 is a low cost full-featured microprocessor. 6502 was originally second-sourced by Rockwell and Synertek and later licensed to a number of companies. It’s one-sixth the price ($25) of the similar products from other well established competitors ($179, Intel 6800).  Since the cost in building a computer has been lowed at that time, it eventually result in home computer revolution of the 1980s. Nowadays, 6502 is still made for embedded systems and video game console.

6502 bought the Home Computer Revolution

Due to their cost are low,  the 6502 and Z80 bought us to the age of “Home Computer Revolution” in 1980s. 6502 home computers such as: Commodore RadioShack TRS-80, Commodore PET, Apple II, BBC Micro, Atari 800XL, etc were appeared in consumer market in 1980s.  People started to have their own computers.  (My father bought an Apple ][ computer in 1983 with HK$4500 (which is around US $600).)

At that time, most of the 6502  home computers come with a BASIC interrupter.  And the software are mainly written in BASIC or assembly languages.

History of 6502 Technology

A  6502 processor is firstly packaged in a DIP-40 plastic package and was designed by the same development team that had designed the Motorola 6800. Thus, 6502 and 6800 process a lot of similarities, such as: single accumulator and small number of registers. In addition, the 6502 processor introduces the idea of “zero page” which improves the speed of communication. A 6502 can also be used to handle BCD calculation.

The first development board of 6502 processor launched to the market was MDT-650. Then KIM-1, Rockwell AIM65 and Synertek SYM-1 were also launched to the market. Those 6502 development boards were welcomed to both engineers and hobbyists, thus it leaded to widespread acceptance to the market.

One of the first publicly marketed computers using the 6502 technology was the Apple I computer in 1976. Later, there are Apple II and Commodore PET, Atari home computers, BBC Micro family, etc came to the market and bought the trend of 6502 computers.

6502 processor not only bought great influences to computers market, it developed the video game console, too. Most of the video game consoles uses refined version of 6502 processors.  The first video game console which uses 6502 technology was the Atari 2600. Atari 2600 uses a simplified version of 6502, 6507 which can only address 8KB memory.