CHAPTER 11

ASSEMBLER OVERVIEW

An assembler performs the clerical function of converting your assembly language program into machine-executable form. It accepts your source file and, depending on the output options selected, can produce an executable object file, a listing of the source and assembled code, and a symbol cross-reference listing.

The ISIS-II 8080/8085 Macro Assembler (ASM80) runs under the Intel Systems Im- plementation Supervisor (ISIS-II) and resides on the ISIS-II system diskette. Opera- tion of the ISIS-II assember is the subject of this manual.

Details for loading and controlling the ISIS-II assembler are given in Chapters 2 and

3.List formats are shown in Chapter 4. Error messages issued by the assembler are listed in Chapter 7. Chapter 5 describes the linkage conventions for passing parameters from an assembly language program module to a PL/M module. The hardwarelsoftware environment requirements are summarized below.

ISIS-II Assembler Environment

The ISIS-II assembler uses the following hardware:

Intellec system with 32K RAM memory (48K if source contains macros)

Console device (TIY or CRT)

Diskette unit

Line printer (if available)

This assembler runs under ISIS-II, which includes the Locater, Linker, and Library Manager.

Overlay and Nonoverlay Operating Modes

The ISIS-II assembler can be run in either an overlay or nonoverlay mode. Overlay mode requires only 32K of Intellec memory and is selected by specifying the NOMACROFILE control (described in Chapter 2). This control can be specified only if your program does not include macros.

If your program has macros, or if you want faster assemblies, specify the MACROFILE control. Your Intellec system must have a 48K memory in this case, but the assembler can run in nonoverlay mode. Specifying MACROFILE also adds the macro reserved symbols (MACRO, ENDM, LOCAL, REPT, IRP, IRPC, EXITM) to the list of reserved words.

No matter how much Intellec memory you have, the assembler runs in overlay (slower) mode unless you specify MACROFILE. (NOMACROFILE is the default control.) Both modes use an optional overlay to create cross-reference listings.

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Intel 8080, 8085 manual Chapter Assembler Overview, ISIS-II Assembler Environment

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.