COP8SA-DM National Semiconductor, COP8SA-DM Datasheet - Page 22

• Manufacturer Part Number: COP8SA-DM
• Description: MODULE DEBUGGING FOR COP8SA
• Manufacturer: National Semiconductor

Specifications of COP8SA-DM

• Module/board Type: Debugger Module
• For Use With/related Products: Cop 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *COP8SA-DM

Each byte in program memory contains an instruction like ADD or JMP, represented by
a code or opcode (example: 033 = ADD). Instructions are stored in the order to be
executed. For example:
These instructions (8-bit opcodes) might be stored at memory locations 00, 01, and 02. To
execute this code, the program counter (PC) is set to point to location 00 (the PC contains
address 00). The opcode stored at location 00 is read into an instruction register in the
control block. The control block decodes the opcode and executes the LD instruction. The
PC is incremented by one to point to the next instruction (the PC contains 01). Then the
fetch, decode, and execute steps are repeated.
1.7.2
Data memory is used to store and retrieve information. Typically, there are two types of
data memory that caan be used: RAM and/or EEPROM (electrically erasable memory).
Structure
Data Storage
The data memory can contain intermediate result values from math operations
(add/sub), tables, flags, and system stack.
Pointer
A pointer contains an address which specifies a location in memory. A pointer "points" to
the location of some data. A data pointer is used to specify the location of a byte/word in
1-10
LD
INC
JMP
MICROCONTROLLER BASICS
1. Size
2. Von Neumann Architecture
3. Harvard Architecture
Data Memory
The data memory size varies from one microcontroller type or family to an-
other (4-bit/8-bit/16-bit by 16, 32, 64, 128 bytes, etc.)
With Von Neumann architecture data and program memory share the same
memory space. If code is placed in a separate memory space in locations 0000
through 03FF, then data must reside in locations above 03FF.
With Harvard architecture data and program memory have separate memory
spaces. Code may be placed in locations 0000 through 03FF and data may re-
side in locations 000 to 03F.
A,#00
A
00