Configuration Basics
2-6
Am186™CC/CH/CU Microcontrollers User’s Manual
For example, if the segment register is loaded with 12A4h and the offset is 0022h, the
resultant address is 12A62h, as illustrated in Figure 2-3. To find the result:
1. The segment register contains 12A4h.
2. Shift the segment register left 4 places to produce 12A40h.
3. The offset is 0022h.
4. Add the shifted segment address (12A40h) to the offset (00022h). The result is 12A62h.
5. This address is placed on the pins of the microcontroller.
All instructions that address operands in memory must specify (implicitly or explicitly) a
16-bit segment value and a 16-bit offset value. The 16-bit segment values are contained in
one of the four internal segment registers (CS, DS, ES, and SS). For more information about
calculating the offset value, see “Addressing Modes” on page 2-9. For more information
about CS, DS, ES, and SS, see “Segments” on page 2-7.
In addition to 1 Mbyte of memory space, the Am186CC microcontroller provides 64K of I/O
space (see Figure 2-4). Note that the processor reserves 00000h to 003FFh in memory for
the interrupt vector table.
Figure 2-3
Physical Address Generation
2.4
I/O SPACE
The I/O space consists of 64K 8-bit or 32K 16-bit ports. The IN, INS, OUT, and OUTS
instructions address the I/O space with either an 8-bit port address specified in the
instruction, or a 16-bit port address in the DX register. Eight-bit port addresses are zero-
extended so that A15–A8 are Low. Note the processor reserves I/O port addresses 00F8h
through 00FFh. The microcontroller provides specific instructions for addressing I/O space.
1 2 A 4 0
0 0 0 2 2
1 2 A 6 2
1 2 A 4
0 0 2 2
Segment Base
Logical
Address
Shift
Left
4 Bits
Physical Address
To Memory
Offset
0
15
15
15
19
19
0
0
0
0
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...