io by Logon System
IO
a demo by Logon System in 2015
Requirements: at least MSX1 PAL/50HZ 64KB MSX-DOS
Despite MSX1 features only, MSX2 is suggested for better colors & fx.
Copy "IO.COM" on your floppy or partition, MSX-DOS1 or MSX-DOS2.
Type "IO y" for silent mode, beware it automatically switches to 50Hz.
On openMSX emu: insert IO.DSK then reboot; demo will launch thru autoexec.
Beware it's a MSX-DOS1 DSK which should/could not boot on turbo R / DOS2.
Check for possible updated build at:
http://www.msxvillage.fr/download/download.php?cat=4
MSX gurus will likely ask and give advices for fixes, which I will add.
The demo won't run on
- BlueMSX (bad timing, not enough precision for splitrasters)
- NMS8280 (number of cpu cycles on a scanline: not an integer? WTF!?)
- MSX1 with vdp at 60Hz frame rate
- MSX1 with less than 64Kb RAM (see MSX-DOS requirements also)
- MSX whose cpu is overclocked
- ...
The demo has been sucessfully tested on:
- openMSX (dev actually was made on openMSX :)
- Philips VG8235 (MSX2) (my own computer)
- Canon V20 (MSX1)
- Philips VG8020 (MSX1)
- Yeno MX-64 (MSX1)
- Yashica YC-64 (MSX1)
- Sony HB501F (MSX1)
- Goldstar FC-200 (MSX1) (w/ bad sync at start)
- Sanyo PHC-28L (MSX1) (w/ glitch on plasma)
- Philips NMS 8245 (MSX2)
- Philips NMS 8255 (MSX2)
- Sanyo Wavy 35 (MSX2+)
- Panasonic A1WX (MSX2+)
- Panasonic A1WSX (MSX2+)
- Panasonic A1ST (TurboR)
Despite only MSX1 features are used,
I would suggest to watch on a standard MSX2 (with 1 clock for cpu&vdp),
in order to get splitrasters and colors as initially thought.
Note that there's also a lame patch about splitrasters on Turbo R & co.
It started with some tests on a platform which I didn't know.
Then came the idea to rush and release 2 fx as POC.
Finally it ended as a short demo.
What have I tested and is included?
- rasters
- splitrasters
- changing sprite colors at each scanline
- changing kind-of palette/all colors at each scanline
- splitscreen
- screen splitted at each scanline
- sprites multiplexing (to enhance SC2 gfx)
- constant time YM/AYC player
- unlimited sprites by page-flipping
- dynamically generated code (rotozoom)
What was unexpected and gave me some headaches?
- too fast vram access!
- sync by bit 5S not fully emulated
- bits 5S & C differences from msx2 to msx1
- IO slow-down on turbo R and some msx+
- 2 clocks for cpu and vdp on some msx
- frequency differences on NMS8280
- MSX-DOS1 vs MSX-DOS2 vs DOS2 rom onboard
- ...
What was the most fun?
- the "Yet Another Plasma!" scene, without any doubt
You might not understand how glad I am to commit such a fx on MSX,
this is my own personal achievement :)
I did it first for myself, and not for you guys! :P
That said, let's share!
Some tools which were used come from the Amstrad CPC scene:
- AYC z80 player (Madram/Overlanders)
- YMcruncher to AYC (F-key/Revival)
Other tools are:
- BitBuster
- BlitzBasic
- Crimson Editor
- Frhed
- openMSX
- SJasm+
Thanks for reading!
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