Some theory behind emulators: emulator types You can group all the CPU emulators out there in 4 main categories: switch-case based; jump-table based; PLA or microcode emulation based; graph based; Graph based emulators are the most accurate as they emulate the connections between transistors inside the die of the CPU. As a Mac user it was a quick tweak to get the code working on the Mac version of PropellorIDE, and the SimpleIDE code worked out the box on the Mac. The expansion header is very useful for hanging a logic analyser from as all the pins from prop, 6502, SRAM etc. Are broken out there.

Easy 6502 by • • • • • • • • • Introduction In this tiny ebook I’m going to show you how to get started writing 6502 assembly language. App for mac computer to write poems and short stories. The 6502 processor was massive in the seventies and eighties, powering famous computers like the,,,, and the. Bender in Futurama.

So, why would you want to learn 6502? It’s a dead language isn’t it? Well, so’s Latin.

And they still teach that. (Actually, I’ve been reliably informed that 6502 processors are still being produced by and, so clearly 6502 isn’t a dead language! Who knew?) Seriously though, I think it’s valuable to have an understanding of assembly language. Assembly language is the lowest level of abstraction in computers - the point at which the code is still readable.

Assembly language translates directly to the bytes that are executed by your computer’s processor. If you understand how it works, you’ve basically become a computer. Then why 6502?

Why not a useful assembly language, like? Well, I don’t think learning x86 is useful. I don’t think you’ll ever have to write assembly language in your day job - this is purely an academic exercise, something to expand your mind and your thinking. 6502 was originally written in a different age, a time when the majority of developers were writing assembly directly, rather than in these new-fangled high-level programming languages. So, it was designed to be written by humans. More modern assembly languages are meant to written by compilers, so let’s leave it to them. Plus, 6502 is fun. Universal samsung printer driver for mac.

Nobody ever called x86 fun. Our first program So, let’s dive in! That thing below is a little that I adapted for this book. Click Assemble then Run to assemble and run the snippet of assembly language. Notes: Memory location $fe contains a new random byte on every instruction. Memory location $ff contains the ascii code of the last key pressed.

Memory locations $200 to $5ff map to the screen pixels. Different values will draw different colour pixels. The colours are: $0: Black $1: White $2: Red $3: Cyan $4: Purple $5: Green $6: Blue $7: Yellow $8: Orange $9: Brown $a: Light red $b: Dark grey $c: Grey $d: Light green $e: Light blue $f: Light grey Hopefully the black area on the right now has three coloured “pixels” at the top left. (If this doesn’t work, you’ll probably need to upgrade your browser to something more modern, like Chrome or Firefox.) So, what’s this program actually doing?

Let’s step through it with the debugger. Hit Reset, then check the Debugger checkbox to start the debugger. Click Step once. If you were watching carefully, you’ll have noticed that A= changed from $00 to $01, and PC= changed from $0600 to $0602. Any numbers prefixed with $ in 6502 assembly language (and by extension, in this book) are in hexadecimal (hex) format. If you’re not familiar with hex numbers, I recommend you read.

Anything prefixed with # is a literal number value. Any other number refers to a memory location. Equipped with that knowledge, you should be able to see that the instruction LDA #$01 loads the hex value $01 into register A. I’ll go into more detail on registers in the next section. Press Step again to execute the second instruction. The top-left pixel of the simulator display should now be white.