2015.03.27
"Halt Catch and Fire"
Got interested in the recent Spider WIP improvements and the correlated Table
Tennis Championship development, I’ve decided to take a look at this exotic
FPGA-based video blitter.
The thing is definitely weird, as Haze also explained in his blog it
basically reads an i/o port to enter into “blitter mode”, and any following
write to the memory mapped bus actually routes to the blitter, and using the
address bus instead of the data bus either for obfuscation or performance
reasons.
It’s not a novelty (Sharp X1 Japanese computer line did something similar
back in 1981) but definitely a bit annoying, and the main roadblock towards
emulation of this game until today:
http://mamedev.emulab.it/kale/wp-content/uploads/2015/03/0026.png
http://mamedev.emulab.it/kale/wp-content/uploads/2015/03/0027.png
http://mamedev.emulab.it/kale/wp-content/uploads/2015/03/0030.png
http://mamedev.emulab.it/kale/wp-content/uploads/2015/03/0031.png
http://mamedev.emulab.it/kale/wp-content/uploads/2015/03/0032.png
来源：http://mamedev.emulab.it/kale/2015/03/25/halt-catch-and-fire/