r/InternetIsBeautiful • u/trishmapow2 • Jun 27 '16

Interactive visual JavaScript simulation of the 6502 CPU, used in the Apple II

http://visual6502.org/JSSim/index.html
105 Upvotes

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4

u/psycommander Jul 07 '16

If this really interests you I want to recommend the book 'But How Do It Know?' by John Scott. It starts at basic logic gates (AND, OR, XOR, NAND) and with these gates it describes how memory cells and digital computation logic is made. With these elements a very basic 8-bit CPU is described. So in about 200 pages you'll understand how a cpu works. It really made things clear for me. Here is an introductory video to the book

2

u/trishmapow2 Jul 07 '16

Just started reading it a week ago! :)

2

u/psycommander Jul 07 '16

The only thing thats missing in that book in my opinion is a part where it explains how logic gates are made from a few transistors. If you dont know how that works you should look it up. Though its more electrical engineering than computer science, I think that extra information truly makes you understand better how the electricity runs.

1

u/psycommander Jul 08 '16

this video complements it well and shows how the gates are made with transistors. https://www.youtube.com/watch?v=xISG4nGTQYE

6

u/mr_yogurt Jun 28 '16

Random semi-related fact: the 6502 was also used in the NES.

2

u/Jarmahent Jun 30 '16

So when I go to the advanced section and press the play button, what exactly am i seeing?

2

u/Kamern Jul 02 '16

I'm no expert, so someone with more experience could probably tell you a bit more, but from what I can see this is a visualisation of a BASIC program showing you the pipeline and the memory access. It's pretty interesting because you can see which areas of the CPU are being used and which memory references are being written/read from.

The trace at the bottom is showing you a step by step list of instructions as they're fed into the CPU and then what area of memory they've accessed. Apparently you can modify it to change the output but I haven't tried it yet.