[http://quasar.cpcscene.net/doku.php?id=coding:test_crtc Test CRTC - Quasar Net]
=== TODO : A better PIO ===
I'm looking after a great implementation of PIO, in original schematic of Amstrad, keyboard (output, not input) is mapped behind Yahama chip behind PIO.
In some emulators, keyboard is mapped directly behind PIO.
In original schematic, PIO is the only one component having a low state reset (0), I think that imply a 0 value as state init of internal components variable. Data bus of Z80 seems having a pull-up state (read 1 when nothing is plugged), for example a unplugged ROM does respond xFF in data-bus.
Update : arnoldemu's testbench PPI passed.
=== TODO : Interlaced scanlines ===
=== TODO : PPI ===
Keyboard detection versus VSYNC signal (interrupt cycle)
==== TODO : A better PIO ====
I'm looking after a great implementation of PIO, in original schematic of Amstrad, keyboard (output, not input) is mapped behind Yahama chip behind PIO.
In some emulators, keyboard is mapped directly behind PIO.
In original schematic, PIO is the only one component having a low state reset (0), I think that imply a 0 value as state init of internal components variable. Data bus of Z80 seems having a pull-up state (read 1 when nothing is plugged), for example a unplugged ROM does respond xFF in data-bus.
Update : arnoldemu's testbench PPI passed.
==== TODO : Yamaha clock ====
In r005.5 I build the Yamaha clock from GA. Unlocking "Saboteur 2" game.