6502 javascript emulator
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In order to do signed calculations, a microprocessor’s arithmetic logic unit (ALU) needs to be able to calculate when an overflow occurs.
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took an in depth look at a small part of the processor: the overflow circuit. The 6502 was a ubiquitous microprocessor back in the 80s, powering devices such as the Apple II and the Nintendo Entertainment System. Posted in computer hacks, how-to Tagged 6502, assembly, tutorial How 6502 Overflow Works It moves on to an overview of registers and instructions, operators and branching, and culminates in the creation of a simple game.
#6502 JAVASCRIPT EMULATOR CODE#
The guide starts off slowly, providing a working program and challenging the reader to play with to code in order to alter the outcomes. You can even find folks building their own computers around the chip these days (most notable to us is the Veronica project). In addition to the previously mentioned Atari they can be found in the Commodore 64, Apple II, and the original NES.
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The 6502 was in a lot of early equipment. The nice thing is that you need nothing more than your browser to participate thanks to the embedded JavaScript emulator which acts as assembler, machine, and debugger in one. It’s an assembly tutorial for the 6502 processor.
#6502 JAVASCRIPT EMULATOR MANUAL#
The write-up (although incredibly fun for us to read) ends up being a reference manual for him once the project starts to get really hairy.Ĭontinue reading “Another Take On The 6502 Computer” → Posted in computer hacks Tagged 6502, 65c02, ATmega32, AVR Learn A Little Assembly Language For The 6502 ProcessorĮvern wanted to write your own Atari 2600 games? This won’t get you quite that far, but it will teach you the very basics. The plan is to get a blog going, which he’s hesitant to do as it takes valuable hacking time away from the project. He’s using a character LCD to display memory location and data values. But it shows that the basic idea works, and the video after the break lets us see another time-saving aspect of the circuit. The chip is simply running NOP commands right now. This chip not only feeds the processor data (through all those slightly diagonal yellow wires) but also provides the clock signal and operates the reset and bus enable lines. As you can see above, there’s an Atmel chip perched above the 65C02 processor. He was inspired by some of the other projects we’ve seen around here, like Veronica Project, but with a spin that leverages modern processors to alleviate some of the messy work. is just starting off on his own 6502 computer odyssey. Posted in computer hacks Tagged 6502, AVR, fifo, idt7200l, interrupts, veronica, vga Another Take On The 6502 Computer It moves one of the time-critical processes out of that single AVR chip to fix the issue by using an IDT7200L FIFO SRAM chip. They are fighting with each other for control of the processor cycles and she fixed it by making the daughter board seen in the image above. The problem is a pair of uninterruptible processes running on the same AVR chip (part of the GPU she built). Now she shows a screenshot and says it’s easily recognizable as a race condition - proving she has a bigger brain than us. After writing the assembly code and loading it into the machine she was dismayed to find that there were dropped characters all over the place. And this step in the journey had a pretty big one in store for. That’s a welcome achievement after watching so much work go into this project.īut with anything this complex you can’t expect to make progress without finding bugs. This proves that native 6502 code is running on the processor and reliably outputting data through its VGA hardware. Well, it’s only showing the word Hello right now, but the concept is the same. The screenshot on the right shows computer project displaying a Hello World program.