z80189 ZiLOG Semiconductor, z80189 Datasheet - Page 133

• Manufacturer Part Number: z80189
• Description: Z80180, Z8s180, Z8l180 Mpu Operation
• Manufacturer: ZiLOG Semiconductor

118
ASCI Transmit Data Register Ch. 0 (TDR0: 06H)
UM005003-0703
Bit
Bit/Field
R/W
Reset
Note: R = Read W = Write X = Indeterminate ? = Not Applicable
Bit
Bit/Field
R/W
Reset
Note: R = Read W = Write X = Indeterminate ? = Not Applicable
ASCI Transmit Data Register Ch. 1 (TDR1: 07H)
Z8018x
Family MPU User Manual
7
7
When transmission is completed, the next byte (if available) is
automatically loaded from TDR into TSR and the next transmission
starts. If no data is available for transmission, TSR idles by outputting a
continuous High level. The TSR is not program-accessible.
ASCI Transmit Data Register 0, 1(TDR0,1:I/O Address = 06H, 07H)
Data written to the ASCI Transmit Data Register is transferred to the TSR
as soon as TSR is empty. Data can be written while TSR is shifting out the
previous byte of data. Thus, the ASCI transmitter is double buffered. Data
can be written into and read from the ASCI Transmit Data Register.
If data is read from the ASCI Transmit Data Register, the ASCI data
transmit operation is not affected by this read operation.
6
6
5
5
ASCI Transmit Channel 0
ASCI Transmit Channel 1
4
4
R/W
R/W
0
0
3
3
2
2
1
1
0
0