Description

This article is from the Apple ][ Emulator Resources Guide, by Alex Maddison with numerous contributions by others.

1.1 What is an emulator?

An emulator is a virtual-copy of a physical device (in terms of this document, an 8-bit or 16-bit Apple computer). Early home computers contained a number of basic hardware components - the ROM (hard-coded software, like a computer-game cartridge), the RAM (writeable application memory) and the CPU (the microprocessor which executes machine-language programs). The original instruction-set of the Apple's CPU is duplicated at the core of the emulator as software, and around this is built further emulation of storage devices (usually disk-drives) and translation so that the virtual-machine can use your physical computer's keyboard, display screen, RAM and sound features. Along with a software copy of the ROM (see below) the emulator can use the resources of your physical computer to mimic an Apple!

If the concept of emulation sounds too good to be true - that's probably because it is. Emulators can use a large percentage of your physical computer's resources during operation. Efficient emulation of the Apple on modern machines is really only possible because of the expanding power of computers. At this point, it takes the processing power of a 486DX2/66 or 68030 CPU to comfortably emulate a 1MHz 6502 (the CPU of the 8-bit Apple ][). The 16-bit IIgs emulators coming into use now need the latest processors (Pentium or PowerPC chips).

 

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• Index
• next: 1.2 What are disk-images?

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pc, hardware, Apple II, Apple ][ or Apple //, apple, emulator, guide, resource