Shape tables are a feature of the Apple II ROMs which allows for manipulation of small images encoded as a series of vectors. An image (or shape) can be drawn in the high-resolution graphics mode—with scaling and rotation—via software routines in the ROM. Shape tables are supported via Applesoft BASIC and from machine code in the "Programmer's Aid" package that was bundled with the original Integer BASIC ROMs for that computer.
Applesoft's high-resolution graphics routines were not optimized for speed,[1] so shape tables were not typically used for performance-critical software such as games, which were typically written in assembly language and used pre-shifted bitmap shapes. Shape tables were used primarily for static shapes and sometimes for fancy text; Beagle Bros offered a number of fonts in Font Mechanic as Applesoft shape tables.
The vectors of a two-dimensional graphic, each encoding a direction from the previous pixel along with a flag indicating whether the new pixel should be illuminated or not, were encoded up to three in a byte. These were stored in a table via the Monitor or the POKE command. From there, the graphic could be referenced by number (a table could contain up to 255 shapes), and built-in Applesoft routines permitted scaling, rotating, and drawing or erasing the shape. An XOR mode was also available to allow the shape to be visible on any color background; this had the advantage, also, of allowing the shape to be easily erased by redrawing it.
Apple did not provide any utilities for creating shape tables; they had to be created by hand, usually by plotting on graph paper, then calculating the hexadecimal values and entering them into the computer. Beagle Bros created a shape table editing program, which eliminated the "number crunching", called Apple Mechanic, and a related program, Font Mechanic.
^Simoni, Richard T. Jr. (August 1983). "A New Shape Subroutine for the Apple". BYTE. p. 292. Retrieved 9 February 2015.
External linksedit
Atariarchives.org example, detailed instructions on assembling shape tables by hand
January 01, 1970
shape, table, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, written, like, personal, reflection, personal, essay, argumentative, essay, that, states, w. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article is written like a personal reflection personal essay or argumentative essay that states a Wikipedia editor s personal feelings or presents an original argument about a topic Please help improve it by rewriting it in an encyclopedic style July 2018 Learn how and when to remove this message This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Shape table news newspapers books scholar JSTOR April 2015 Learn how and when to remove this message Learn how and when to remove this message Shape tables are a feature of the Apple II ROMs which allows for manipulation of small images encoded as a series of vectors An image or shape can be drawn in the high resolution graphics mode with scaling and rotation via software routines in the ROM Shape tables are supported via Applesoft BASIC and from machine code in the Programmer s Aid package that was bundled with the original Integer BASIC ROMs for that computer Applesoft s high resolution graphics routines were not optimized for speed 1 so shape tables were not typically used for performance critical software such as games which were typically written in assembly language and used pre shifted bitmap shapes Shape tables were used primarily for static shapes and sometimes for fancy text Beagle Bros offered a number of fonts in Font Mechanic as Applesoft shape tables Contents 1 Technical details 2 See also 3 References 4 External linksTechnical details editThe vectors of a two dimensional graphic each encoding a direction from the previous pixel along with a flag indicating whether the new pixel should be illuminated or not were encoded up to three in a byte These were stored in a table via the Monitor or the a href PEEK and POKE html title PEEK and POKE POKE a command From there the graphic could be referenced by number a table could contain up to 255 shapes and built in Applesoft routines permitted scaling rotating and drawing or erasing the shape An XOR mode was also available to allow the shape to be visible on any color background this had the advantage also of allowing the shape to be easily erased by redrawing it Apple did not provide any utilities for creating shape tables they had to be created by hand usually by plotting on graph paper then calculating the hexadecimal values and entering them into the computer Beagle Bros created a shape table editing program which eliminated the number crunching called Apple Mechanic and a related program Font Mechanic See also editSpriteReferences edit Simoni Richard T Jr August 1983 A New Shape Subroutine for the Apple BYTE p 292 Retrieved 9 February 2015 External links editAtariarchives org example detailed instructions on assembling shape tables by hand Retrieved from https en wikipedia org w index php title Shape table amp oldid 1226100619, wikipedia, wiki, book, books, library,
