diff --git a/mode7_demo/docs/mode7_demo.tex b/mode7_demo/docs/mode7_demo.tex index bbb195b3..7d3a5316 100644 --- a/mode7_demo/docs/mode7_demo.tex +++ b/mode7_demo/docs/mode7_demo.tex @@ -94,11 +94,13 @@ put this one to shame. \section{The Hardware} The Apple II was introduced in 1977. -This demo should run on an original system, though I do not -have hardware quite that old to test on. -I like to troll C64 fans by noting this predates the Commodore 64 by +In theory this demo will run on hardware this old, although I do +not have access to a system of that vintage. +I like to troll Commodore fans by noting this predates the Commodore 64 by five years. + + \vspace{1ex} \noindent {\bf CPU, RAM and Storage:} @@ -151,12 +153,12 @@ Hardware page flip & Yes \\ \end{tabular} \end{center} -The hi-res graphics mode was a complex mess of NTSC hacks by Woz. -You got approximately 280x192 resolution, with 6 colors available. -However the colors were from NTSC artifacts and there were limitations -on which colors could be next to each other (in blocks of 3.5 pixels). -There was plenty of fringing on edges, and colors changed depending on -whether they were drawn at odd or even pixels. +The hi-res graphics mode is a complex mess of NTSC hacks by Woz. +You get approximately 280x192 resolution, with 6 colors available. +The colors are NTSC artifacts with limitations +on which colors can be next to each other (in blocks of 3.5 pixels). +There is plenty of fringing on edges, and colors change depending on +whether they are drawn at odd or even locations. To add to the madness, the framebuffer is interleaved in a complex way, and pixels are drawn least-significant-bit first (all of this to make DRAM refresh better and to shave a few 7400 series logic chips from the design). @@ -168,11 +170,12 @@ Optionally 4 lines of text can be shown at the bottom of the screen instead of graphics. The lo-res mode is a bit easier to use. -It provides 40x48 blocks (40x40 if the four -lines of text are displayed at the bottom). +It provides 40x48 blocks, reusing the same memory as the 40x24 text mode. +(As with hi-res you can switch to a 40x40 mode with four lines of +text displayed at the bottom). Fifteen colors are available (there are two greys which are indistinguishable). -Again the addresses are interleaved. Lo-res Page 1 is at \$400 -and Page 2 is at \$800. +Again the addresses are interleaved in a non-linear fashion. +Lo-res Page 1 is at \$400 and Page 2 is at \$800. Some amazing effects can be achieved by cycle counting, reading the floating bus, and racing the beam while toggling graphics