Find all your DIY electronics in the MakerShed. 3D Printing, Kits, Arduino, Raspberry Pi, Books & more!

In September of last year, Matt Mets blogged about Visual 6502, an in-browser simulation of the landmark MOS 6502 microprocessor, produced by San Francisco hacker Greg James and Montreal brothers Barry and Bryan Silverman.

Recently, the July/August issue of the American Institute for Archaeology’s Archaeology featured an interesting article about the story behind Visual 6502. It provides a concise overview of the 6502′s historical significance, and then goes on to cast the team’s reverse-engineering project in terms of “digital archaeology,” emphasizing the “excavation” metaphor: Like physical archaeologists, James and the brothers Silverman “dig” into the chip package, itself, to recover lost knowledge of our history.

Back in 1974, the original schematic for the 6502 was sketched out by hand on a drafting board. (In contrast, today’s design methodology has hundreds of engineers working on hundreds of computers creating archived digital files of their work when collaborating on today’s microprocessors.) The creator of the 6502’s schematic doesn’t know where that document is today, and very little information on how the chip was created survives. Further, in the more than 35 years since its design, the understanding of how this remarkable chip performed its functions was lost.

[Thanks, Michelle!]

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.


Related

Comments

  1. Scott Morrison says:

    While it is entirely plausible that the original drawings have been lost, I find it seriously hard to believe that the understanding of how a 6502 “performed its functions” was lost to the ages. Many people have created virtual 6502s using FPGA chips, seems like it would be hard to replicate something in software if no one understands how it works.

    1. Tim Kemp says:

      From the article: “the understanding of how this remarkable chip performed its functions was lost”.  I don’t think they are saying that no one knows how to do what the 6502 did.  I believe they are saying that exactly how the 6502 performed some operations was lost.

      I can write a program to play a game of checkers.  Without understanding exactly how my program works you could write a checker playing program.  Externally they may work exactly the same, but internally they may be completely different.  In fact that is intentionally done many times and is known as a clean room design.

  2. Tim Kemp says:

    I loved the 6502.  Back in 1978, when I learned to program, it was the first processor I used.  It had a simple, but clean architecture.  Until I used the 68000 the 6502 remained my favorite.  The others I had to use in the middle (i.e. Z-80, 8085, 8088, 8080, etc.) were a mess in comparison.  From the years I spent hand assembling and disassembling 6502 code I still remember the hex values of many of the instructions.

    In the many years since then I’ve seen echos of the 6502 in many of the better processors I’ve used.  It’s nice to see it being remembered in newer processors and here.

  3. Tim Kemp says:

    I loved the 6502.  Back in 1978, when I learned to program, it was the first processor I used.  It had a simple, but clean architecture.  Until I used the 68000 the 6502 remained my favorite.  The others I had to use in the middle (i.e. Z-80, 8085, 8088, 8080, etc.) were a mess in comparison.  From the years I spent hand assembling and disassembling 6502 code I still remember the hex values of many of the instructions.

    In the many years since then I’ve seen echos of the 6502 in many of the better processors I’ve used.  It’s nice to see it being remembered in newer processors and here.

  4. Anonymous says:

    My wife, before she was my wife, took an assembly language programming course which used the KIM-1 (basically an evaluation board for the 6502). She hand-assembled her code and keyed it in on the KIM-1′s hex keypad. I remember discovering and showing to her,  a cross-assembler which ran on the school’s CDC Cyber 74.  She wasn’t interested and preferred to continue assembling by hand. 

    Back in the day when you could do stuff like that…

  5. Anonymous says:

    My wife, before she was my wife, took an assembly language programming course which used the KIM-1 (basically an evaluation board for the 6502). She hand-assembled her code and keyed it in on the KIM-1′s hex keypad. I remember discovering and showing to her,  a cross-assembler which ran on the school’s CDC Cyber 74.  She wasn’t interested and preferred to continue assembling by hand. 

    Back in the day when you could do stuff like that…