Apple2048

a.k.a. Apple 2048

published by author in 2014-07-25, running on Apple II E

type: puzzle
genre: Transport puzzle
perspective: bird's-eye
player options: single player

languages: eng

Technical specs

software: Apple ProDOS,

display: text

Editor note

This game uses some quirks of the two memory pages for text modes of certain Apple II systems to provide full screen animated graphics constructed of text. As many Apple II users know, text can usually be perceived as it is printed to the screen because the system is as slow an most 8-bit computers. But Jeremy Rand has large independent sections of text based graphics sliding around the screen with no perception of character-by-character printing. Parallax scrolling (in text mode) could be convincingly faked using this method. It is done by telling the Apple to display one 40 column page while the other 40 column page is being written to. This is in no way how the two pages of text were meant to be used. Rather, the 'second page' is meant to be the right half of text in 80 column mode (the first page is the left half). The IIe enhanced (IIe + 80 column card), Apple IIc, and Apple IIgs are supported. Supporting the IIgs is especially notable since there was some hardware differences in the IIgs' Apple IIe mode graphics, basically enforcing the intended use of the second text page and running IIe mode with half the amount of display RAM, that causes some games, both text and graphical games, to not work properly. The IIgs uses software emulation and native RAM to shadow the IIe mode's second page, swapping it in and out constantly at 8-bit 6502 CPU speed. Basically, halving the frame rate but also borking games that want to fiddle with two pages of display RAM. In fact, it is not possible for the IIgs to run this game properly. It would require enabling the "Alternate Display Mode" option (slow display mode) to run at all. How is it then done full speed on the IIgs? Rand cheats. When the game detects it is running on a IIgs, it uses 16-bit IIgs assembly routine to swap the memory pages natively (at 16-bit 65816 CPU speeds) then it returns to running the 8-bit IIe game without the IIe mode ever having to swap pages itself. Thus it is one of the rare Apple II games that can use IIgs native code.