"Hardware description of the 8051 microcontrollers" - читать интересную книгу автора (Hennig-Roleff W.)

6.1 Interrupt logic 58
6.2 Timer0 and Timer1 61
6.3 serial communications 62
6.3.1 asynchronous, synchronous mode 63
6.3.2 serial mode set up 63
6.3.3 Interrupt Mode, Polled Mode 67
6.3.4 Baud rate table 70
7. further controller of the 8051 Family 71
7.1 the 8052 71
7.1.1 additional SFR of the 8052 71
7.1.2 Timer2 71
7.1.3 serial communications with timer2 73
Appendix
A.1 ASCII table ........................................ 75
A.2 Instruction set in hexadecimal order ............. 77


1. 8051 Characteristics Page 1
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1. 8051 characteristics
-----------------------


The 8051 is often embedded in control circuits, for that reason the name
microcontroller has been commonly used for the 8051.


The 8051 operates on an 8 bit data bus. Externally it can address 64 kByte of
data and code separately. Additionally it has internal RAM (128 Byte) and
internal ROM (4 kByte) of program memory.
Instructions from addresses 0000 to 0FFFh operate from internal program
memory. Instructions from higher addresses will always be read from external
program memory. Through an input pin the internal program memory can be
switched off.

Most of the instructions need one cycle (1 Ўs) to execute.
The data manipulation instructions are as follows:

MOV (data transfer),
XCH (data exchange),
INC, DEC (increment +1, decrement -1),
ANL, ORL, XRL (logic operations),
ADD, ADDC, SUBB (addition, subtraction),
MUL, DIV (multiplication, division).


A special feature of the 8051 is that almost all its electrical connections
(pins) can be accessed with software. It also has access to two integrated
timers, one serial port (UART) as well as two interrupt inputs.