B69000 Asiliant Technologies, B69000 Datasheet - Page 118

• Manufacturer Part Number: B69000
• Manufacturer: Asiliant Technologies

Specifications of B69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

CR17
read/write at I/O address 3B5h/3D5h with index at address 3B4h/3D4h set to 17h
7
6
Note:
5
Note:
4
&+,36
CRT Ctrl
Reset
7
CRT Controller Reset
0: Forces horizontal and vertical sync signals to be inactive. No other registers or outputs are
affected.
1: Permits normal operation.
Word Mode or Byte Mode
0: The memory address counter’s output bits are shifted by 1 bit position before being passed on
to the frame buffer address decoder such that they are made into word-aligned addresses when bit
6 of the Underline Location Register (CR147) is set to 0.
1: The memory address counter’s output bits remain unshifted before being passed on to the frame
buffer address decoder such that they remain byte-aligned addresses when bit 6 of the Underline
Location Register (CR14) is set to 0.
This bit is used in conjunction with bits 6 and 5 of the CRT Mode Control Register (CR17) to control
how frame buffer addresses from the memory address counter are interpreted by the frame buffer
address decoder as shown below:
See the note at the end of this register description.
Address Wrap
0: Wrap frame buffer address at 16KB. This is used in CGA-compatible modes.
1: No wrapping of frame buffer addresses.
This bit is only effective when word mode is made active by setting bit 6 in both the Underline
Location Register and this register to 0.
See the note at the end of this register description.
Reserved
69000 Databook
CR14
Bit 6
Word or Byte
CRT Mode Control
0
0
1
1
Mode
6
CR17
Bit 6
0
1
0
1
Word Mode -- addresses from the memory address counter are shifted
once to become word-aligned
Byte Mode -- addresses from the memory address counter are not shifted
Doubleword Mode -- addresses from the memory address counter are
shifted twice to become doubleword-aligned
Doubleword Mode -- addresses from the memory address counter are
shifted twice to become doubleword-aligned
Address
Wrap
5
Subject to Change Without Notice
CRT Controller Registers
Reserved
4
Addressing Mode
Count By 2
3
Retrace Sel
Horizontal
2
Select Row
Scan Cntr
Revision 1.3 8/31/98
1
Mode Supp.
Compat
0
9-25