I'm confused about the diode AND Gate CR9 & CR10 to Suppress the Left and Right Boundary Signals. How does a Diode AND Gate "Suppress" a signal? and What are "Boundary" Signals?
"Boundary" signals, in this instance, are the left and right bars at the edge of the screen (and also the top) - see diagram 3-2 on page 6 of the manual. You'll see this as LH SIDE, RH SIDE, and TOP BOUND. Naturally in an AND gate, both inputs must be high for the output to turn on. CR9 cathode is low until 128V+64V+16V+8V+4V are on (we'll draw this out later). !HSYNC applied to CR10 cathode forces the CR9/CR10 anode pair off, keeping the LH SIDE and RH SIDE signals off. Also, since the monitor is rotated 90 degrees clockwise, LH, RH and TOP are from a play view perspective. The V and H signals are from the normal monitor perspective. Other interesting signal names: PSYNC=Paddle, BSYNC=Ball, BPHIT=Ball/Paddle Hit, BTBHIT=Ball/Top Boundary Hit. The flip-flops in the center of sheet 1 control ball motion direction. For example, D5a controls direction of the ball towards the top or paddle (they call this x-direction). You can see this flip-flop set when the ball hits the paddle (BALL DISPLAY + PSYNC), and reset when it hits the top (BSYNC + TOP BOUND). You would think they would use BSYNC for both but...
Great work! Enjoying this series - very interesting.
I'm confused about the diode AND Gate CR9 & CR10 to Suppress the Left and Right Boundary Signals. How does a Diode AND Gate "Suppress" a signal? and What are "Boundary" Signals?
"Boundary" signals, in this instance, are the left and right bars at the edge of the screen (and also the top) - see diagram 3-2 on page 6 of the manual. You'll see this as LH SIDE, RH SIDE, and TOP BOUND. Naturally in an AND gate, both inputs must be high for the output to turn on. CR9 cathode is low until 128V+64V+16V+8V+4V are on (we'll draw this out later). !HSYNC applied to CR10 cathode forces the CR9/CR10 anode pair off, keeping the LH SIDE and RH SIDE signals off. Also, since the monitor is rotated 90 degrees clockwise, LH, RH and TOP are from a play view perspective. The V and H signals are from the normal monitor perspective.
Other interesting signal names: PSYNC=Paddle, BSYNC=Ball, BPHIT=Ball/Paddle Hit, BTBHIT=Ball/Top Boundary Hit. The flip-flops in the center of sheet 1 control ball motion direction. For example, D5a controls direction of the ball towards the top or paddle (they call this x-direction). You can see this flip-flop set when the ball hits the paddle (BALL DISPLAY + PSYNC), and reset when it hits the top (BSYNC + TOP BOUND). You would think they would use BSYNC for both but...