Contents
How does the 6502 work?
A computer bus has the job of transferring data and signal around the machine. For a 6502, they are three of them: If you want to carry more data than that two separate signals will have to be sent down the bus. This means you can transfer the number 00011000 in one trip, but 00110001 00110101 will take two.
How many instructions is 6502?
Of the 256 possible opcodes available using an 8-bit pattern, the original 6502 uses 151 of them, organized into 56 instructions with (possibly) multiple addressing modes. Depending on the instruction and addressing mode, the opcode may require zero, one or two additional bytes for operands.
What does sta$ 0200 do?
The top-left pixel of the simulator display should now be white. This simulator uses the memory locations $0200 to $05ff to draw pixels on its display. So, the instruction STA $0200 stores the value of the A register to memory location $0200 .
What is 6502 assembly language?
6502 assembly is a very low-level language that works specifically for the 6502 microprocessor — a very popular processor from the 1970s.
What still uses 6502?
> They are still found as embedded cores in computer mouses and keyboards, monitors (OSD processor/scaler), digital picture frames (https://spritesmods.com/?art=picframe&page=1), MP3 players, Furby (https://news.ycombinator.com/item?id=17751599 , actually a 6502-subset) etc.
What kind of addressing does the 6502 do?
Indexed memory ops The 6502 has the ability to do indexed addressing, where the X or Y register is used as an extra offset to the address being accessed. Absolute Indexed This addressing mode makes the target address by adding the contents of the X or Y register to an absolute address.
How is the 6502 code used in an emulator?
This addressing mode makes the target address by adding the contents of the X or Y register to an absolute address. For example, this 6502 code can be used to fill 10 bytes with $FF starting at address $1009, counting down to address $1000.
What is the hex for the Intel 6502?
The hex for this is 4C 32 40. The 6502 is a little endian machine, so any 16 bit (2 byte) value is stored with the LSB first. All instructions that use absolute addressing are 3 bytes. Zero-Page Zero-Page is an addressing mode that is only capable of addressing the first 256 bytes of the CPU’s memory map.
How to transfer control to$ 4080 using 6502?
For example if address $3000 contains $40, $30FF contains $80, and $3100 contains $50, the result of JMP ($30FF) will be a transfer of control to $4080 rather than $5080 as you intended i.e. the 6502 took the low byte of the address from $30FF and the high byte from $3000. Affects Flags: none