DEC VT220 Technical Manual page 217

ADDRESS
17C8H (WRI
07 06 05 04 03 02 01 00
IBAD7 HI .... . . - - - - - - - - - - - - - - - - - -........... (BADO HI
BIT VALUES
BIT
()-4
xx
BINARY DEFINITION OF NUMBER OF SCAN LINES
MINUS ONE, IN EACH DATA ROW i9H for
10 SCAN L1NESI
NOTE
BITS 5 THROUGH 7 ARE USED AS 3 MSB. OF
SCAN LINES PER VERTICAL PERIOD REGISTER
AND ARE WRITTEN TO AT SAME TIME AND
ADDRESS AS BiTS
0-4
ABOVE.
Mll-OlSll·"
Figure C-22 9007 VPAC: Scan Lines
Per Data Row Register
ADDRESS
1lCBH (WR, 3 MS8sj
ADDRESS
17C9H (WR lOW BYTE,
06
05
04
03
02 01 00
:•
o"~.",,,,
:
:
15 14
13
12 11
10
09 08
BiT BIT BiT
' : ' 0 ,"":'
10
9
8
IBAD7
Hi"
.. IBADO HI
BIT VALUES
BIT 0-10 BINARY DEFINITION OF NUMBER OF SCAN LINES IN
ENTIRE VERTICAL PERIOO (TRACE AND RETRACEI
NOTES·
1 VERTiCAL BLANKING PERiOD IS DEFINED BY
SUBTRACTING THE TOTAL NUMBER OF SCAN
LINES PER VERTICAL TRACE IVALUE OF DATA
ROWS PER FRAME REGISTER X VALUE OF
SCAN LINES PER DATA ROW) FROM ABOVE
VALUE
2 FIVE LSDs OF HIGH BYTE ARE USED AS SCAN
LINES PER DATA ROW REGISTER
(REF FIGURE C·221
Figure C-23 9007 VPAC: Scan Lines
Per vertical Period Register
C-14