
6.0 ACCESS.bus Interface
(Continued)
Revision 1.2
131
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P
6.3.6
This register provides a fast way to float the outputs of one or more modules through the ACCESS.bus without having to
access their TRI-STATE Control bit in the Special Configuration register at index F0h. The module outputs enter TRI-STATE
only when the module is disabled (see Section 6.3.5 on page 130). The register is reset by hardware to 00h.
Power Well: V
SB
Location:
Offset 04h
Type:
R/W
ACCESS.bus TRI-STATE Register (ACBTRIS)
Bit
Name
Reset
7
6
5
4
3
2
1
0
Reserved
0
KBMSTRIS
0
SER1TRIS
0
SER2TRIS
0
PARPTRIS
0
FDCTRIS
0
0
0
Bit
Description
7-5
Reserved.
4
KBMSTRIS (Keyboard and Mouse Outputs TRI-STATE).
When set to 1 and the module is disabled, this bit
forces the outputs of the Keyboard and Mouse Controller to be in TRI-STATE regardless of bit 0 in the Keyboard
Configuration register (see Section 3.13.3 on page 69).
0: Enabled or Disabled, according to bit 0 in the Keyboard Configuration register (default)
1: Outputs in TRI-STATE
3
SER1TRIS (Serial Port 1 Outputs TRI-STATE).
When set to 1 and the module is disabled, this bit forces the
outputs of the Serial Port 1 module to be in TRI-STATE regardless of bits 6 and 0 in the Serial Port 1
Configuration register (see Section 3.11.3 on page 66).
0: Enabled or Disabled, according to bits 6 and 0 in the Serial Port 1 Configuration register (default)
1: Outputs in TRI-STATE
2
SER2TRIS (Serial Port 2 Outputs TRI-STATE).
When set to 1 and the module is disabled, this bit forces the
outputs of the Serial Port 2 module to be in TRI-STATE regardless of bits 6 and 0 in the Serial Port 2
Configuration register (see Section 3.10.3 on page 64).
0: Enabled or Disabled, according to bits 6 and 0 in the Serial Port 2 Configuration register (default)
1: Outputs in TRI-STATE
1
PARPTRIS (Parallel Port Outputs TRI-STATE).
When set to 1 and the module is disabled, this bit forces the
outputs of the Parallel Port module to be in TRI-STATE regardless of bit 0 in the Parallel Port Configuration
register (see Section 3.9.3 on page 62).
0: Enabled or Disabled, according to bit 0 in the Parallel Port Configuration register (default)
1: Outputs in TRI-STATE
0
FDCTRIS (Floppy Disk Controller Outputs TRI-STATE).
When set to 1 and the module is disabled, this bit
forces the outputs of the Floppy Disk Controller module to be in TRI-STATE regardless of bit 0 in the FDC
Configuration register (see Section 3.8.3 on page 59).
0: Enabled or Disabled, according to bit 0 in the FDC Configuration register (default)
1: Outputs in TRI-STATE