Register Functions; Vram Configuration - Sharp mz-800 Technical Reference And User's Manual

4-7 Register functions
VRAM configuration
• One or two chips of 16 KB VRAM are used.
• In the case of a single 16 KB VRAM chip, it handles
320 x 200 dots, 4 colors, or 640 x 200 dots 1 calor.
• In the case of two 16 KB VRAM chips, it handles 320
x 200 dots, 16 colors, 640 x 200 dots, 4 colors, 320 x
200 dots, 4 colors, 2 frames, or 640 x 200 dots, 1
calor, two frames.
*
Discussed next are about functions of the custom LSI.
There may be some restrictions because the standard
version of the MZ-800 incorporates only one 16 KB
RAM.
Display mode register (OUT
&HCE)
• lt consists of four bits which are used to represent
display method, resolution, and display screen (calor
plane) in combined way.
Display mode register (DMD)
MSB
DMD
2
DMD
1
LSB
DMD
0
• DMD 3, 2: Display method and resolution
DMD
2
3
0
0
Bit map, 320 x 200
0
1
Bit map, 640 x 200
1 0
MZ-700 mode
1 1 Prohibited
• DMD 1, 0: Display screen designation
DMD DMD
320
X
200
640
X
200
1 0
0 0
Frame A, Planes I and II Frame A, Plane I
0 1 Frame B, Planes
m
and IV
Frame B, Plane
m
(NOTE)
1
0
Planes I, II,
m,
and N Planes I,
m
1 1 Prohibited
NOTE: 640 x 200, Plane B is Plane
m,
not Plane II.
• With the MZ-800, DMD 1
=
0, DMD 0
=
0.
Table-1 VRAM configuration and display mode
VRAM
VRAM configuration
Resolution
Display Display Color combination DMD
capacity col or frame (NOTE) 3 2
c5?,_,
8000"
G
320
X
200 4 colors Frame A
I. IT 0
0
9FFF H
16 KB
VA0-7
8000H
t
640 X 200 1 color Frame A I 0 1
8
BFFF
Frame A I,
n
0
0
VA0-7 VC 0-7
~
4 colors
320
X
200 Frame B
m,
IV
0
I
0
-"~
I II
9FFF
16 colors Frame A
1.
n. m.
IV 0
0
32 KB
VA0-7 VC 0-7
Frame A
I
0 1
i
l
1 calor
8000
0
G
640
X
200 Frame B
m
0 1
BFFF
4 colors Frame A I.
m
0
1
MZ-700
40 characters
8 colors Frame A RGB 1 0
x 25 lines
(NOTE) Except for the MZ-700 mode, actual display colors are produced by the pallet.
17
MZ-700
Normal
Prohibited
Prohibited
&.
3/3
1 0
0
0
0 0
0
0
0
1
1 0
0 0
0 1
1 0
0 0
0
4
'
'
~I
)