Path: sun!vector.Sun.COM!poynton
From: poynton@vector.Sun.COM (Charles Poynton)
Newsgroups: sun.tstech
Subject: Re: sync ratios on new Sony 19"
Summary: Here are the integers.  Work out the rest yourself!
Message-ID: <124860@sun.Eng.Sun.COM>
Date: 16 Sep 89 23:37:07 GMT
References: <8909141644.AA01768@barbados.>
Sender: news@sun.Eng.Sun.COM
Reply-To: poynton@Sun.COM (Charles Poynton)
Distribution: sun
Organization: Sun Microsystems, Mountain View
Lines: 35
Approved: usenet@sun.com


> "what are the sync ratios and any other pertinant specs of the new 
> 19 inch Sony monitor".

The following timing information is applicable to all current 1152-by-900
colour Sun framebuffers and monitors, including the 16" Sony GDM-1604 and
the 19" Sony GDM-1955.  Both of these have vertical refresh of about 
66 Hz, different from the corresponding standard Sony monitors (GDM-1601
and GDM-1950) which are designed for 60 Hz.

I have learned to give this data in the form of exact integers, which the
user can then round off to the precision he requires, rather than giving
rounded numbers which the user may need to spend hours reverse-engineering
to get the exact integer values.  This has the side benefit that naiive
users can't mis-interpret data which they don't understand.

Pixel clock	     92.9405 MHz

H total			1504 clocks
H front porch		  29 clocks
H sync			 128 clocks
H active		1152 clocks

V total		 	 937 lines
V front porch		   2 lines
V sync			   4 lines
V active		 900 lines

Video is 714 mV p-p including 7.5% setup, with SEPARATE sync on a fourth
wire (i.e. there is NO sync on the green channel).

To get H frequency, divide pixel clock by H total clocks:  

  H total               1504 clocks    61.796 kHz

To get the duration of a horizontal feature, just divide the
corresponding clock count by the pixel clock frequency.  [Or more
intuitively, take the reciprocal of the pixel clock frequency to obtain
the pixel time, and multiply that by any of the clock counts to get the
corresponding duration.]:

  H front porch	          29 clocks
  H sync                 128 clocks
  H active      	1152 clocks

  H blanking 1504-1152 = 352 clocks     3.787 us

To get V frequency, divide H frequency by V total lines:  

  V total                937 lines     65.95 Hz

To get the duration of any of the vertical features, just divide the
corresponding line count by the horizontal frequency.  [Or more
intuitively, multiply the H total duration by any of the line counts below
to get the corresponding duration.]:

  V front porch	           2 lines
  V sync                   4 lines
  V active               900 lines

  V blanking   937-900 =  37 lines    599 us

C.