HD66750/1
47
WM0
WM15
1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1
DB0
DB15
1 0 1 1 1 1 0 0 0 1 1 0 0 0 0 1
1 1 0 0 0 0 1 1 1 0 0 0 1 1 0 0
0 1 1 1 0 1 0 0 0 0 0 1 1 1 1 1
1 0 0 1 1 0 0 1 0 1 0 0 0 0 1 1
0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0
0 0 0 0 1 1 1 0 1 1 1 0 0 1 1 0
000H
CGRAM
010H
020H
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
4-bit rotation
4-bit rotation
4-bit rotation
1 1 0 1 1 1 1 0 0 0 1 1 1
1 0 0
0 1 1 1 1 0 0 1 1 1 0 0 0
1 1 0
1 1 1 1 1 1 1 1 0 0 1 1 1
1 1 1
*
*
*
*
*
*
1 1 0 1 1 1 1
0
0 1 1 1 1 0 0
0
1 1 1 1 1 1 1
1
7F0H
1 0 1 1 1 1 0 0 0 1 1 0
0 0 0 1
1 1 0 0 0 0 1 1 1 0 0 0
1 1 0 0
0 1 1 1 0 1 0 0 0 0 0 1
1 1 1 1
000H
001H
Write data mask:
Write data (1):
Write data (2):
Write data (3):
Read data (1) + Write data (1)
Read data (1):
Read data (2):
Read data (3):
Logical operation (OR)
Logical operation (OR)
Logical operation (OR)
Read data (2) + Write data (2)
Read data (3) + Write data (3)
1) I/D = 1, AM1D0 = 01, LG1D0 = 01 (OR), RT2D0 = 010
2) WM15D0 = FC03H
3) AC = 000H
Operation Examples:
Notes: 1. The bit area data in the RAM indicated by '*' is not changed.
2. After writing to address 7F0H, the AC jumps to 001H.
Figure 30 Writing Operation of Read/Write Mode 2
6. Read/Write mode 3: AM1D0 = 10, LG1D0 = 01/10/11
This mode is used when the data is written with high speed by vertically shifting bits and by performing
logical operation with the original data. It can be also used to write the 16-bit data for two words into the
graphics RAM (CGRAM), develop the font pattern, or transfer the BiTBLT as a bit unit. This mode can
read the data during the same bus cycle as for the write operation since the read operation of the original
data does not latch the read data into the microcomputer and temporarily holds it in the read-data latch.
The rot a i on func t on (R T2D0) or wr it e -dat a m as k func t on (W M 15D0) ar e al s o ena bl ed i n t hes e
oper at ons Howe ver, al hough t he wr it e -dat a m as k func t on m as ks t he bi pos i on s et wi h t he wr it e -
data mask register (WM15D0) at the odd-times (such as the first or third) write, the function masks the bit
pos i on whi ch re ver se d t he s et ng val ue of t he wr it e -dat a m as k re gi st e r (W M 15D0) at t he eve n-t m es
(s uc h as t he s ec ond or four th) wr it e Af te r t he odd-t m es wr it ng, t he addr es s count e r (A C)
automatically increments by 1 (I/D = 1) or decrements by 1 (I/D = 0). After the even-times writing, the
AC aut om at ca y i ncr em ent s or dec re me nt s by D1 + 16 (I /D = 1) or + 1 + 16 (I /D = 0). The AC
automatically jumps to the upper edge after it has reached the lower edge of the graphics RAM.