NEC Advanced Personal Computer System Reference Manual page 77

Controller PCB
Table 3-4 GDC
~ymbols
(cont'd)
SYMBOL NAME
DESCRIPTION
DE Display Enable Controls display start (DE
=
1) or display
stop (DE
=
0).
DIR Direction Controls drawing direction.
D Dynamic RAM
D
=
1 implies display buffer consists of
dynamic RAM; otherwise (D
=
0) consists
of static RAM.
F Flashless Mode
Controls for flashless drawing (F
=
1) or
flashing drawing (F
=
0).
G Graphic Mode Not used; see CHR.
HBP Horizontal
Defines the amount of left horizontal
Back Porch
blanking time.
HFP Horizontal
Defines the amount of right horizontal
Front Porch
blanking time.
HOS Horizontal Sync
Horizontal sync occurs when HOS
=
1.
I Interlace
Display is interlaced (I
=
1) or not inter-
laced
(I =
0).
LIN
Line
LIN = 1 indicates that line is being
drawn.
L/F
Lines Per Frame
Defines the number of lines in the vertical
display period.
L/R
Lines Per Row
L/R defines the number of lines in each
row.
M Master
M = 0 indicates GDC is in multi (slave)-
mode; M
=
1 indicates single (master)-
mode. The APC only uses master mode.
3-12