🚀 go-pugleaf

	I have been experimenting with the ATARI 520ST in EXTERNAL SYNC mode
and I am looking for some help. This is not well documented. I will
post a summary of E-mail replies (if I get any). Anyone at ATARI listinging???

Here is what I have done:
	Set $ff820a to $fd from $fc and drive HSYNC pin 9 and VSYNC pin12
via 470 ohm resisters from an external source. The video information does 
NOT seem to follow HSYNC input *exactly* but rather seems drift for about 
a byte then re-sync !!!!

Very odd.
See diagram below.

VSYNC	================================
     H  |.
     S	| . <= Video boarder
     Y	|  .
     N  |   . <= drifting away from the horizontal boarder!!!
     C  |. <= after about 8 pixels it instantly reverts to the
	| . <= boarder again !!!
	|  .
	|   . <= slope is a function of drift from NTSC norm.
	|.
	| .
		etc.
The camera is NOT running HSYNC *exactly* at the same HSYNC that
the ATARI would if it were providing syncs. Should not this slack
be taken up in the blanking area? Of course I know little about the
chip as it is....What should I do with *BLANK and DE on the GLUE chip
are they converted to inputs also ????

	I am making a sampling digitizer that uses the ATARI for
timing with respect to the syncs.  Any help would be MOST welcome.

Mike Gore	Institute of Computer Research.