[comp.sys.ibm.pc.misc] Need to know about a few CGA ports

II70038@MAINE.BITNET (Jonathan Kimball) (09/25/90)

Could someone tell me what ports or registers on the CGA card are used to:
1. Determine if the card is in vertical(not horizontal) retrace.
2. Enable/Disable blinking.
3. Enable/Disable underscore.
 
Jonathan Kimball
II70038 at MAINE.BITNET

halco@iccgcc.decnet.ab.com (10/13/90)

In article <90267.162100II70038@MAINE.BITNET>, II70038@MAINE.BITNET (Jonathan Kimball) writes:
> Could someone tell me what ports or registers on the CGA card are used to:
> 1. Determine if the card is in vertical(not horizontal) retrace.
> 2. Enable/Disable blinking.
> 3. Enable/Disable underscore.

VSYNC is indicated by a "1" at bit 00001000, port 3DAH.

Blinking is enabled by setting bit 00100000, port 3D8H.  You must set the
blink bit (10000000) in the attribute byte of each character you want to
blink.  This also forces the background color of all characters to be the
same.

As far as underlining, I don't think it can be be done on CGA.

						Have fun.
						Bruce Halco 

>  
> Jonathan Kimball
> II70038 at MAINE.BITNET