This program will simply create screens… Just sit back and enjoy! GRAFIX II is a graphics display program: after loading it waits for a key and then runs a 5,945-byte machine-code routine that draws its screens. There is nothing to control.
Credited on screen to Kristian Boisvert, ©1987 Byte Power, and listed by the magazine as “Graphic entertainment”. Loading name GRAFIX II. Published on the Fall 1987 (Issue 8) tape of Byte Power.
Program Analysis
The BASIC is a short loader. Line 10 does CLEAR 49000, fills the screen with inverse spaces and prints the title; line 20 points the character set (CHARS, 23606–23607) at the screen area before loading the code block at 49648, so the tape header message is printed as unreadable dots, and line 25 restores it (POKE 23607,60). Line 40 waits with PAUSE 0 and starts the code with USR 5E4 (50000).
The code block appears to begin with a lookup table of display-file row addresses, the usual way to plot quickly on the Spectrum-style screen. The rest has not been decoded.
Notable Techniques
- Temporarily redirecting
CHARSto hide the “Bytes:” message during loading. USR 5E4written in exponent form, which takes fewer keystrokes than 50000.- The usual Byte Power backup guard: with
PEEK 23681=0the program lists its save line instead of running.
Image Gallery
Note: Type-in program listings on this website use ZMAKEBAS notation for graphics characters.