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Blanking: Difference between revisions
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'''Blanking''' is the cutting of electronic current from the cathode to the screen in a CRT television while it is switched on. | '''Blanking''' is the cutting of electronic current from the cathode to the screen in a CRT television while it is switched on. | ||
'''Vertical blanking''' occurs when the electron beam reaches the bottom-right of the screen and needs to be reset to the top-left again. | '''Vertical blanking''' occurs when the electron beam reaches the bottom-right of the screen and needs to be reset to the top-left again. The VBLANK signal is generated by [[S-PPU2]] (pin 26), which is fed into the [[S-CPU]] through pin 44. | ||
'''Horizontal blanking''' occurs when the electron beam reaches the end of a [[scanline]] and needs to be reset to the beginning of the next scanline. | '''Horizontal blanking''' occurs when the electron beam reaches the end of a [[scanline]] and needs to be reset to the beginning of the next scanline. The HBLANK signal is also generated by [[S-PPU2]] (pin 25), which is fed into the [[S-CPU]] through pin 43. | ||
'''Forced blanking''' occurs when the [[PPU]] nearly switched off, so it is generating black, but this is not part of the TV's sync pulse. | '''Forced blanking''' occurs when the [[PPU]] nearly switched off, so it is generating black, but this is not part of the TV's sync pulse. | ||
Revision as of 21:52, 4 May 2023
Blanking is the cutting of electronic current from the cathode to the screen in a CRT television while it is switched on.
Vertical blanking occurs when the electron beam reaches the bottom-right of the screen and needs to be reset to the top-left again. The VBLANK signal is generated by S-PPU2 (pin 26), which is fed into the S-CPU through pin 44.
Horizontal blanking occurs when the electron beam reaches the end of a scanline and needs to be reset to the beginning of the next scanline. The HBLANK signal is also generated by S-PPU2 (pin 25), which is fed into the S-CPU through pin 43.
Forced blanking occurs when the PPU nearly switched off, so it is generating black, but this is not part of the TV's sync pulse.