M69030 Asiliant Technologies, M69030 Datasheet - Page 167

• Manufacturer Part Number: M69030
• Manufacturer: Asiliant Technologies

Specifications of M69030

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 70C
• Rad Hardened: No
• Lead Free Status / Rohs Status: Supplier Unconfirmed

Chapter 12
Attribute Controller Registers
Introduction
Unlike the other sets of indexed registers, the Attribute Controller Registers are not accessed through a
scheme employing entirely separate index and data ports. I/O address 3C0h is used both as the read and
write for the index register, and as the write address for the data port. I/O address 3C1h is the read address
for the data port.
Table 12-1:
To write to one of the attribute controller registers, the index of the desired register must be written to I/O
address 3C0h and then the data is written to the very same I/O address. A flip-flop alternates with each
write to I/O address 3C0h to change its function from writing the index to writing the actual data and back
again. This flip-flop may be deliberately set so that I/O address 3C0h is set to write to the index (which
provides a way to set it to a known state) by performing a read operation from Input Status Register 1 (ST01)
at I/O address 3BAh or 3DAh (depending on whether the graphics system has been set to emulate an MDA
or a CGA).
To read from one of the attribute controller registers, the index of the desired register must be written to I/O
address 3C0h and then the data is read from I/O address 3C1h. A read operation from I/O address 3C1h
does not reset the flip-flop to writing to the index. Only a write to 3C0h or a read from 3BAh or 3DAh, as
described above, will toggle the flip-flop back to writing to the index.
`efmp
AR00-AR0F
Name
AR10
AR11
AR12
AR13
AR14

69030 Databook
Attribute Controller Registers
Function
Mode Control Register
Overscan Color Register
Memory Plane Enable Register
Horizontal Pixel Panning Register
Color Select Register
Color Data Registers
Attribute Controller Registers
read/write
read/write
read/write
read/write
read/write
read/write
Access
Revision 1.3 11/24/99
Index
00-0F
10
11
12
13
14
12-1