Re: Tv oscillator
One more thing: what is the grayscale supposed to look like? Horizontal or vertical? Or a combination? The latter would be the hardest. Any of the other two would be relatively easy.
I will try to post something for you. Meanwhile, here is the basic idea: you build a 1MHz crystal oscillator, follwed by a divide by 64 counter. That will give you the horizontal synch pulses. Divide that by 625 and you get the vertical synch pulses. Note that this system will only produce 312 lines, instead of 625, so it will be non-interlaced, but it will work very nicely and it will be much easier to build.
Use intermediate signals from the divider and AND them with synch pulses to obtain the correct synch pulse widths and blanking signals. The two synch signals should be XORED together to achieve the composite synch signal, which will in fact "chop" the vertical synch pulse, as required. You will not need any pre-equalization, nor post-equalization pulses. Remember, this is non-interlaced video.
To achieve the grayscale, build one (or two) sawtooth generator, using simply a constant current source that charges up a capacitor. The blanking pulses will be used to discharge the cap (basically short it to GND). That way, the sawtooth is synchronized with the synch pulses (it should be clear by now why I say only one grayscale is easiest to achieve).
The control voltage will be used to actually adjust the current that charges up the capacitor. The capacitor only charges between the blanking pulses (recall that the blanking pulses discharge the cap). So, depending on how fast the cap charges, the amplitude of the voltage at the end of the interval will be higher or lower, resulting in a different contrast. So use the third control voltage to actually vary the cap's charging current and you achieve linear contrast control.
Finally, combine all these elements (ramp, blanking, synch pulses), using resistors (and transistors possibly) and you will have your generator. The final amplitude of the video signal should be 1Vpp (the standard amplitude). Then you can test it by feeding it to your VCR video input and viewing it on your TV.