Absolute Programs, Relocatable Programs | Intel 8080, 8085 specification

CHAPTER 61 RUNNING YOUR PROGRAM

Absolute Programs

If your program was assembled using the ASEO location counter, you may be able to load and test your program on the Intellec development system immediately after it is assembled. Notice, however, that your program must include an ORO directive that will cause the program to load into a memory location that will not conflict with ISIS-II. (ORO 4000H loads your program well above ISIS-II.) If your program does not include such an ORO directive, it must be reassembled before you attempt to execute it.

To execute your program, you need only enter its object file name in response to an ISIS-II prompt. For example, assume that your program's name is MYPROO. By default, its object file name is MYPROO.OBJ. Entering MYPROO.OBJ after an ISIS-II prompt loads the program and starts its execution.

Program execution begins at the address specified as the operand of the END direc- tive in the source program. If this address is missing or conflicts with ISIS-II, the program cannot be executed.

Relocatable Programs

Some portion of your program has been assembled in the relocatable mode if the program contains a CSEO or DSEO directive. Such programs are not directly exe- cutable since some addresses are assembled relative to zero rather than any actual address. To resolve these addresses, you must submit your object file to the LOCATE program. LOCATE supplies absolute addresses for the relocatable ad- dresses. Notice that you can supply absolute load addresses through the LOCATE program. These addresses override any ORO directives in your program. Also, you must be certain to locate your program so that is does not conflict with ISIS-II.

If your program comprises a number of separately assembled modules, you must submit the object file to the LINK program before using LOCATE. The LINK pro- gram binds together the separate modules and resolves any external addresses speci- fed by EXTRN directives.

The final product of LINK (if needed) and LOCATE is an absolute object program file. You can run this program as though it were assembled as an absolute program. Program execution begins at the address specified as the operand of an END direc- tive in the source program. When the program comprises separately assembled modules, only one module may specify a start address in its END directive. If this address is missing or conflicts with ISIS-II, the program cannot be executed.

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8080, 8085 specifications

The Intel 8085 and 8080 microprocessors were groundbreaking innovations in the world of computing, paving the way for future microprocessor development and personal computing.

The Intel 8080, introduced in 1974, was an 8-bit microprocessor that played a fundamental role in the early days of personal computing. With a 16-bit address bus, it had the capability to address 64 KB of memory. Running at clock speeds of 2 MHz, the 8080 was notable for its instruction set, which included 78 instructions and 246 opcodes. It supported a range of addressing modes including direct, indirect, and register addressing. The 8080 was compatible with a variety of peripherals and played a crucial role in the development of many early computers.

The microprocessor's architecture was based on a simple and efficient design, making it accessible for hobbyists and engineers alike. It included an 8-bit accumulator, which allowed for data manipulation and storage during processing. Additionally, the 8080 featured registers like the program counter and stack pointer, which facilitated program flow control and data management. Its ability to handle interrupts also made it suitable for multitasking applications.

The Intel 8085, introduced in 1976, was an enhancement of the 8080 microprocessor. It maintained a similar architecture but included several key improvements. Notably, the 8085 had a built-in clock oscillator, simplifying system design by eliminating the need for external clock circuitry. It also featured a 5-bit control signal for status line management, which allowed for more flexible interfacing with peripheral devices. The 8085 was capable of running at speeds of up to 3 MHz and had an extended instruction set with 74 instructions.

One of the standout features of the 8085 was its support for 5 extra instructions for stack manipulation and I/O operations, which optimized the programming process. Additionally, it supported serial communication, making it suitable for interfacing with external devices. Its 16-bit address bus retained the 64 KB memory addressing capability of its predecessor.

Both the 8080 and 8085 microprocessors laid the groundwork for more advanced microprocessors in the years that followed. They demonstrated the potential of integrated circuits in computing and influenced the design and architecture of subsequent Intel microprocessors. Their legacy endures in the way they revolutionized computing, making technology accessible to a broader audience, and their influence is still felt in the design and architecture of modern microprocessors today.