added snippet explaining the NES's 6502 variant and long-term goal for the project

README.md

@@ -2,10 +2,20 @@
 A Nintendo Entertainment System (NES) emulator written for the purpose of
 understanding how the NES and similar 8-bit computers of that era worked.
 
-Makes heavy use of https://www.nesdev.org/.
+The NES used a variant of the MOS 6502 8-bit microcontroller called a
+Ricoh 2A03 that contained the 6502 without the BCD mode for arithmetic,
+an audio signal generator (APU), controlling the gamepads, and for DMA.
+([Source: NESdev](https://www.nesdev.org/wiki/DMA))
+
+A major goal for the emulator is finishing the software implementation
+in C and later implement this in hardware with either an FPGA or another
+CPU like a RISC-V. Later, I want to generalize the 2A03 simulator into
+a full 6502 for use with a Commodore 64 and Apple II.
+
+Makes heavy use of the [NESdev wiki](https://www.nesdev.org/wiki).
 
 ## Current State
-- [x] CPU (2A03/6502)
+- [x] CPU (Ricoh 2A03, variant of MOS 6502)
 - [ ] PPU (Graphics)
 - [ ] APU (Audio)