548
Digital Electronics
Data,
Pointer and
Index Registers
(8)
Bus
Interface
Unit
INTA, RD, WR
DT/R, DEN, ALE
AD -AD
15
0
A /S
16 3
A /S
19 6
BHE/S7
4
16
3
3
Instruction
Queue (6)
Control and Timing
2
3
LOCK
S , S , S
2
1
0
QS , Qs ,
0
1
3 GND
Vcc
CLK
RESET
READY
MN/MX
ALU (16)
Flags
2
TEST
INT
NMI
HOLD
HLDA
{
Register File
Execution Unit
{
Relocation
Register File
Bus Interface Unit
Segment
Register and
Instruction
Pointer (8)
RQ/GT 0,1
Figure 13.15 Block diagram of 8086.
13.10.2 80186 Microprocessor
The Intel 80186 is packaged in a 68-pin leadless package. It includes the Intel 8086 and several
additional functional units on a single chip. The major on-chip circuits included are a clock generator,
two independent DMA channels, a programmable interrupt controller, three programmable 16-bit
timers and a chip select unit. It operates at a maximum frequency of 10 MHz.
13.10.3 80286 Microprocessor
The 80286 microprocessor is an advanced version of the 8086 microprocessor that was designed for
multi-user and multitasking environments. It addresses 16 MB of physical memory and 1 GB of virtual