6502 8-Bits Based Computer

What

Emulation of a simple 8-Bits computer based on the famous 6502 chip. Supports the original 56 legal instructions even interrupts like NMI and IRQ. Inspired in the Ben Eater 6502 YouTube Serie: https://www.youtube.com/watch?v=LnzuMJLZRdU&list=PLowKtXNTBypFbtuVMUVXNR0z1mu7dp7eH

The 6502 code is a port to typescript from the javidx9 C++ javidx9 C++ 6502 Implementation in his NES Emulator YouTube Serie. https://www.youtube.com/watch?v=8XmxKPJDGU0

NesHacker 6502 JavaScript utility for 6502 programming, which has been extended with extra commands to support label address at compile time. https://github.com/NesHacker/6502

Commands

`.org`

This command set the absolute program address at the point of invocation. It is useful for defining patch segements for ROM hacks.

; Set the absolute program offset to $8000
.org $8000

`.addr`

This command set the absolute program address of a label. Useful for defining label address.

.addr my_label    ; Place the address of my_label

`.word`

This defines 2 bytes to be processed by the assembler. Useful for defining configuration bytes or some address.

.word $FFFC     ; Literal 2 bytes: $FF, $FC

`.byte` or `.byt`

This defines a run of arbitrary bytes to be processed by the assembler. Useful for defining lookup tables or text segments.

.byte 16, 32, 64   ; Literal bytes: $10, $20, $40
.byte "Hello"      ; Literal bytes: $48, $65, 6C, $6C, $6F

Memory Layout

There is 64KB of memory and this is broken into

0x0000 - 0x00FF - Free (Zero Page)

0x0100 - 0x01FF - Stack

0x0200 - 0x5FFF - Free

0x6000 - 0x6FFF - VIA - Versatile Interface Adapter

0x6000 - 0x6000 - VIA - PortB Register

0x6001 - 0x6001 - VIA - PortA Register

0x6002 - 0x6002 - VIA - PortB Direction Data Register

0x6003 - 0x6003 - VIA - PortA Direction Data Register

0x60FE - 0x60FE - VIA - Random Value Register

0x7000 - 0x8000 - Free

0x8000 - 0xFFF9 - Program - always make sure to assemble programs for this address

0xFFFA - 0xFFFA - NMI - Non-Maskable Interrupt Vector Location

0xFFFA - 0xFFFC - RESB - Reset Vector Location

0xFFFA - 0xFFFE - IRQB - Interrupt Request Vector Location

Code Examples

Infinte Count: infinite_count.s

Shift Left With Interrupt: interrupt.s

Installation

Download or clone repository.

Install Angular Cli

    npm install -g @angular/cli

Clone

git clone https://github.com/blackshark537/6502.git

NPM

npm i --save

Build

ng build

Running

ng serve

License

Licensed under the MIT License.

blackshark537/6502