Motorola 68000 Architecture.pdf
Motorola 68000 Architecture.pdf - https://urluso.com/2tvKSJ
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Motorola 68000: A 16/32-bit CISC Microprocessor
The Motorola 68000 (also known as m68k or 68k) is a 16/32-bit complex instruction set computer (CISC) microprocessor that was introduced in 1979 by Motorola Semiconductor Products Sector. It was designed to implement a 32-bit instruction set, with 32-bit registers and a 16-bit internal data bus. The address bus was 24 bits and did not use memory segmentation, which made it easier to program for. Internally, it used a 16-bit data arithmetic logic unit (ALU) and two more 16-bit ALUs used mostly for addresses. It also had a 16-bit external data bus.
The Motorola 68000 was widely used in various applications, such as personal computers, workstations, video games, embedded systems, and industrial control. Some of the notable systems that used the Motorola 68000 were the Apple Macintosh, the Commodore Amiga, the Atari ST, the Sega Genesis, and the Sun Microsystems Sun-1 and Sun-2. The Motorola 68000 was also the basis for the Motorola 68000 series of microprocessors, which included several successors and variants with different features and performance.
The Motorola 68000 architecture was designed to be simple and orthogonal, with a uniform register set and a consistent instruction format. The instruction set consisted of over 90 instructions, which could operate on eight data registers (D0-D7) and seven address registers (A0-A6). The address register A7 was also used as the stack pointer. The instructions could manipulate data of various sizes: byte (8 bits), word (16 bits), or long word (32 bits). The instructions could also perform arithmetic, logical, bit manipulation, shift and rotate, branch and jump, subroutine call and return, exception handling, and system control operations.
The Motorola 68000 had two privilege levels: user mode and supervisor mode. User mode was intended for normal application programs, while supervisor mode was intended for operating system and device drivers. Supervisor mode had access to additional instructions and registers, such as the status register (SR), which contained various flags and bits to control the processor's operation. The Motorola 68000 also supported seven levels of interrupts (0-6), which could be triggered by external devices or internal exceptions. The interrupts could be masked or prioritized by setting the interrupt mask (I) bits in the SR.
The Motorola 68000 was fabricated using NMOS technology, with about 68,000 transistors. It was initially clocked at 4 MHz to 8 MHz, but later versions reached up to 16.67 MHz. It had a typical power consumption of about 1.35 W at 5 V. It was packaged in a 64-pin dual in-line package (DIP). The Motorola 68000 was later replaced by more advanced microprocessors in the Motorola 68000 series, such as the Motorola 68010, the Motorola 68020, and the Motorola 68030.
References:
CPU Architectures Motorola 68000 - Department of Computer Science ...
Motorola 68000 - Wikipedia
Module Introduction - NXP
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