Editing Apple ProDOS (section)

==Requirements==
All editions of ProDOS require an Apple II or compatible.

ProDOS 8 requires 64 KB of memory to run. The original ProDOS (8) 1.0 through 1.0.2 requires only 48 KB for the kernel, but nearly all programs, including the {{mono|BASIC.SYSTEM}} needed to use [[Applesoft BASIC]], require 64 KB, making a 48 KB system useless for ProDOS as a practical matter, and support for 48 KB machines was removed in version 1.1.

ProDOS 8 version 2.x requires a [[WDC 65C02|65C02]] or later (65802, [[65816]]) [[central processing unit|CPU]].  ProDOS 8 2.x runs in 64 KB, but the utility programs on the system disk require 128 KB.  Systems with a 6502 CPU instead of a 65C02 must use ProDOS 8 versions prior to version 2.0.

ProDOS 16 requires an [[Apple IIGS]].

===Unlicensed Apple II clones===
With the release of ProDOS version 1.01 and higher, a check was added to see if it was running on an official Apple-manufactured computer. If the word "Apple" is found in the computer's [[read only memory|ROM ]] [[firmware]], ProDOS will load up as normal. If anything else is found (e.g. "Golden", "[[Franklin Electronic Publishers|Franklin]]", "Elite") ProDOS refuses to run, locking up at the boot [[splash screen]]. This measure was taken by Apple Computer to discourage use of unlicensed Apple II [[clone (computing)|clones]]. It is still possible to run newer versions of ProDOS on clones by applying a small byte [[patch (computing)|patch]] to a given version of ProDOS. Some users go as far as replacing their physical ROM chip(s) with an illegally copied version of Apple's own ROM, or a custom patched ROM with "Apple" added in the name.