Apple IIc Video Port Breakout
During KansasFest 2020 there was a talk about video output options for the Apple IIc. A Apple IIc adapter Audio/Video out connector being sold on eBay was demonstrated. Like everybody else in attendance, I purchased one of these Audio/Video breakout adapters.
The adapter is well put together. It is true that there is a built-in NTSC video port on the Apple IIc. However, the Monitor port includes audio support and a higher quality video output than the built-in video port.
As we learned during the KansasFest presentation, it turns out that the Apple IIc video port includes and audio and video breakout.
|1||TEXT||Video text signal from TMG; set to inverse of GR, except in double high-resolution mode.|
|2||14M||14M master timing signal from the system oscillator.|
|3||SYNC*||Displays horizontal and vertical synchronization signal from IOU pin 39.|
|4||SEGB||Displays vertical counter bit from IOU pin 4; in text mode, indicates second low-order vertical counter; in graphics mode, indicates low-resolution.|
|5||1V SOUND||One-volt sound signal from pin 5 of the audio hybrid circuit (AUD).|
|6||LDPS*||Video shift-register load enable from pin 12 of TMG.|
|7||WNDW*||Active area display blanking; includes both horizontal and vertical blanking.|
|8||+12V||Regulated +12 volts DC; can drive 300mA.|
|9||PRAS*||RAM row-address strobe from TMG pin 19.|
|10||GR||Graphics mode enable from IOU pin 2.|
|11||SEROUT*||Serialized character generator output from pin 1 of the 74LS166 shift register.|
|12||NTSC||Composite NTSC video signal from VID hybrid chip.|
|13||GND||Ground reference and supply.|
|14||VIDD7||From 74LS374 video latch; causes half-dot shift high.|
|15||CREF||Color reference signal from TMG pin 3; 3.58 MHz.|