1. Eight-bit CPU with registers A (Accumulator) and B.
2. Sixteen-bit program counter (PC) and data pointer(DPTR)
3. Eight-bit program status word (PSW)
4. Eight-bit stack pointer(SP)
5. Internal ROM or EPROM (8751) of 4k bytes
6. Internal RAM of 128 bytes :
(a) Four register banks, each containing eight registers
(b) Sixteen bytes, which may be addressed at the bit level
(c) Eight bytes of general purpose registers
7. Four 8-bit I/O ports (P0-P3)
8. Two 16-bit timer/counter TO and T1
9. Full duplex serial data receiver/ transmitter : SBUF
10. Control register: TCON, TMOD, SCON, PCON, IP and IE
11. Two external and two internal interrupt sources
12. Oscillator and clock circuits
