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65 lines
3.5 KiB
Plaintext
65 lines
3.5 KiB
Plaintext
ReadMe for the C:\AppleX\GRAPHICS subdirectory
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This subdirectory contains the source code for a modified and enhanced version
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of the graphics library that was originally shipped with the Aztec C 6502
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cross-compiler. It is called G2.LIB
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It also contains a makefile which can be used to build a new version of this
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library should you decide to add your own routines or modify the routines that
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have been provided. You will have no need to build a new version of the
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library other than that since the G2.LIB that this makefile produces is
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already in place in the C:\AppleX\LIB subdirectory.
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This library is targetted at PRODOS 8 running on an Apple IIe with 128K of
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memory
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This library was developed by Canadian Software Developer Bill Buckels for
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an educational software project in the early 1990's called the "Collection Les
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Petites espadrilles" for use in Elementary Schools. The programs were based on
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their IBM-PC counterparts which had been released a couple of years prior to
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the Apple versions and the expectation was that the Apple versions would
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behave as closely as possible to the IBM versions.
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The Manx C compiler provided a rudimentary Graphics Library, but came nowhere
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close to what Bill needed to complete the four programs in the "Collection Les
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Petites espadrilles" that he had undertaken to write. So he set to work to
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create the graphics and the sound routines that the Apple versions needed to
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behave as closely as possible to their IBM-PC counterparts.
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The graphics used in the IBM-PC versions (4 Color CGA Mode) were vastly
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different from Apple II graphics (which were a coarser resolution), and each
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and every screen and graphics image needed to be redrawn, and reformatted for
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the Apple II. Using the Graphics from the IBM-PC version as a starting point,
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Bill developed his own Apple II graphics file formats and programmed his own
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set of conversion tools which he ran on the IBM-PC to produce the Apple II
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graphics after creating and editing these in IBM-PC format to suit the Apple
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II display. He did this in conjunction with writing his Manx C graphics
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library, since both tasks were complimentary. When the graphics images and
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graphics and sound library routines were completed he moved forward to writing
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the programs.
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Not only did the Apple II have less capable graphics than the IBM-PC; it also
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ran more slowly with only 128K of memory, some of it unusable, and with slower
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disk access and a smaller floppy disk size. To overcome all of this Bill broke
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his Manx C Apple programs into small modules called "overlays" which ran in
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very little memory, and he used the upper ram bank of the Apple II to store
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his graphics libraries and other data to avoid loading from disk where
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possible. Since the Manx C compiler translates its programs into machine
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language which runs as quickly as can be on the Apple II, no optimization or
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additional "tweaks" were required, except to script the game levels using
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external scripts (also of Bill's design) which further saved on disk space and
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program memory, and which avoided slow processor intensive operations that
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would otherwise have been needed.
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The finished results ran more slowly than their IBM-PC counterparts, but for
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all practical purposes had all the same functionality.
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The G2.LIB contains all the library routines used in the Apple versions of the
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"Collection Les Petites espadrilles" and greatly extends the Aztec C 6502
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programming environment. These routines are not exclusively limited to
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graphics and include sound and keyboard routines as well.
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Review the source code and sample programs for more information.
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End of ReadMe
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