Chapter I - Introduction

INTRODUCTION

The Amiga Personal Computer is a low-cost, high-performance system with advanced graphics and sound features. We call it the world's first personal supercomputer. That's a strong statement but one that is substantiated by the Amiga's capabilities.

This chapter contains a brief overview of the Amiga PC hardware, a guide to the rest of this manual, and a system-wide glossary. The first part of the hardware overview describes all of the physical hardware modules, and the second part briefly summarizes the functions of the special purpose graphics and audio hardware and how it interacts with the main processor.

FEATURES SUMMARY (PHYSICAL HARDWARE MODULES)

Here is a list of the physical hardware components of the Amiga Personal Computer.

• Motorola 68000 16/32-bit main processor
  

• 256K bytes of internal RAM, user-expandable to 512K, in a 16-megabyte contiguous space (external expansion also available)
  

• 192K or ROM containing a real-time, multi-tasking operating system with sound, graphics, and animation support routines
  

• A built-in 3-1/2 inch double-sided disk drive. Disks are 80-track, double-sided, formatted as 11 sectors per track, 512 bytes per sector (over 900,000 bytes per disk).
  

• An expansion disk port for connecting up to 3 additional disk drive units. The disk drives may be either 3-1/2 inch or 5-1/4 inch, double sided.
  

• A fully programmable serial port allowing baud rates of beyond 31250 baud
  

• A fully programmable parallel port. Normally, the port is configured as a Centronics [tm] parallel printer output, or it can be used as a high-speed parallel input port.
  

• A two-button opto-mechanical mouse
  

• Two reconfigurable controller ports (for mice, joysticks, paddles, or custom controllers)
  

• A detached 89-key keyboard with calculator pad, function keys, and cursor keys
  

• Ports for simultaneous NTSC, composite video, and analog or digital RGB output
  

• Ports for audio output to left and right stereo channels from 4 special-purpose audio channels
  

• An expansion connector for adding such accessories as RAM, additional floppy or hard disk drives, peripherals, or coprocessors
  

HARDWARE INTERACTION

If the previous list of hardware features alone is not enough to distinguish the Amiga PC from other personal computers, then this section should convince you that the "personal supercomputer" claim is justified. This description of the way the Amiga's hardware elements work together will show how the Amiga provides a unique blend of versatility and raw performance.

MOTOROLA 68000 PROCESSOR

The Motorola 68000 is a 16/32-bit microprocessor operating at 7.1 megahertz. In the Amiga PC, the 68000 can address over 8 megabytes of contiguous random access memory (RAM). The 68000 shares the lowest half-megabyte of RAM space with the Amiga's special-purpose graphics and sound direct memory access (DMA) hardware. Both the 68000 and the special-purpose hardware can read and write into this lowest-address memory region.

ACTUAL OPERATING SPEED OF THE 68000

Performance for the 68000 is enhanced by a system design that gives it every alternate bus cycle, allowing to run at full rated speed most of the time. As described in the section below, the special-purpose hardware can steal time from the 68000 for jobs it can do more efficiently than the 68000. Even then, such cycle stealing only blocks the 68000's access to the shared memory. When using ROM or external memory, the 68000 always runs at full speed.