ZEDDY35
ZEDDY35 demo version 1.0 The ZX81 was released 35 years ago, March 5th 1981, and there are still people exploring ways to (ab)use the little door stopper. Happy 35th anniversary! This is a demo with a static 64x48 character framebuffer that is shown on a 34x24 screen, scrolled pixel-wise in both x- and y-direction at full framerate. Designed to work on a plain unexpanded ZX81 (1k RAM) with an 8k EPROM. Burn the binary to an 8k EPROM and replace the basic-ROM to view the demo on real HW. EightyOne v1.2 emulator works OK, previous versions do not. Select the ROM in hardware/advanced settings/ make sure the NTSC-flag is correctly set depending on what ROM you use. It will be very interesting to see how many other emulators work correctly ;) Enclosed in this archive are the ROM-binaries for PAL and NTSC, this text- file, source-code (FASMW-ZX was used) and python converter utilities for font- and framebuffer-files. Pixel y-scrolling is done by resetting the ULA line counter at the proper time, and starting to generate the correct character line. Pixel x-scrolling is done by changing between 8 predefined character-sets. This limits the number of characters to 8. Changing the framebuffer pointer is also needed for both x- and y-scrolling. I've tested this version to work correctly on: - EightyOne emulator v1.2, 1k RAM, PAL and NTSC. - Unexpanded ZX81 with 1k RAM, real EPROM and S4 romulator, PAL and NTSC, cheap 5" B/W TV (RF and composite) and Sony studio monitor PVM-8045Q (composite). Both EightyOne and FASMW-ZX are Windows programs that work very well for me in Linux/Wine. Enjoy the show, and be inspired by the source-code! 2016-01-14, Adam Klotblixt (NollKollTroll)
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