VBLANK = $01
Control the vertical blank signal.
Ground port path.
Latch control.
WRITE | Name | D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0
| |
$01 | VBLANK | DUMP | LATCH | VBLANK |
Details
Control vertical blank and the latches and dumping transistors on the input ports.
Function | Values | |||||||||
DUMP D7 | Dump path to ground for I6, I1, I2, and I3 ports | 0 = Remove dump path 1 = Dump I6, I1, I2, and I3 ports to ground | ||||||||
LATCH D6 | I4, I5 Latch Control | 0 = Disable I4 and I5 latches, reset latches to logic TRUE 1 = Enable I4 and I5 latches | ||||||||
VBLANK D1 | Vertical Blank | 0 = Stop Vertical Blank 1 = Start Vertical Blank |
TV Frame
A typical TV frame will consists of 3 vertical sync VSYNC lines, 37 vertical blank (VBLANK) lines, TV picture lines (NTSC=192, PAL=242), and 30 overscan lines. See My First Kernel for a code example of the simplest use of VSYNC and VBLANK to form a correct TV frame.
Related
see TIA
see VSYNC
see My First Kernel