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Genlock support in the chipset was quite neat. The genlock contained a Phase Locked Loop that provided the 28.63636 MHz clock input on the video connector so t
by bcrl 4y ago
Genlock support in the chipset was quite neat. The genlock contained a Phase Locked Loop that provided the 28.63636 MHz clock input on the video connector so that the entire system ran off that clock which was synchronized to the video stream. One of the bit planes then controlled if the Amiga's video would overlay the external video source. That was incredibly forward thinking of Jay Miner compared to the offerings of other platforms at the time.
- dylan604 4y agoAre you saying Jay Miner created Genlock or just that it was forward thinking to include on the Amiga? I'm not sure I'd agree with either, as I don't recall the Amiga having Genlock abilities at all. Only 3rd party expansion cards gave the Amiga the ability to Genlock to external video sources so that it was in sync with the rest of the house. For proper Genlock, you have to have some sort of input (typically a black video signal) to use as a sync source, and I just don't recall an Amiga natively having any kind on input like that.
- zerohp 4y agoThe horizontal and vertical syncs[1] (along with the system clock) can be inputs on the video connector. That's what enabled all of the 3rd party genlock hardware. It was designed into the Agnus from the start. Without that you'd need an external framebuffer like an infinite window TBC, which is much more expensive. [1] ERSY mode: http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_guide/node0022.html http://amigadev.elowar.com/read/ADCD_2.1/Hardware_Manual_gui...
- dylan604 4y agoRight, 3rd party, not native to the Amiga which the person I replied to was seemingly implying.
- anyfoo 4y agoNo I get what's meant though. The fact that the Amiga apparently had the native ability to sync its PLL to incoming sync signals (and presumably other clocks are derived from that?) is, for the time and for a general purpose micro at least, nothing short of amazing to me.
- zerohp 4y agoI disagree for the reason that the hardware that is synchronizing the video is the Amiga itself, not the 3rd party hardware. https://retrocomputing.stackexchange.com/questions/22320/what-made-the-amiga-genlock-able https://retrocomputing.stackexchange.com/questions/22320/wha...
- bcrl 4y agoThe PLL is external, but the chipset had the ability to accept an external clock from the start in the Amiga 1000.