• Eight-bit CPU with:
  • Register A (the Accumulator)
  • Register B
  • Instruction set
• Sixteen-bit program counter (PC) and data pointer (DPTR)
• Eight-bit program status (PSW)
• Eight-bit stack pointer (SP)
• Internal ROM or EPROM (8751) of 0(8031) to 4K (8051)
• Internal RAM of 128 bytes:
  • Four register banks, each containing eight registers
  • Sixteen bits, which may be addressed at the bit level:
    128 addressable bits
  • Eighty bytes of general-purpose data memory
• Thirty-two input/output pins arranged as four 8-bit ports: P0-P3
• Two 16-bit timer/counters: T0 and T1
• Full duplex serial data receiver/transmitter: SBUF
• Control registers:
  • TCON
  • TMOD
  • SCON
  • PCON
  • IP
  • IE

©2004, Gary L. Burt