Radio Shack TRS-80 Service Manual page 22

10 PORT DESCRIPTION
Name:
Port Address:
Access:
Description:
LPIN"
0F8H
Retld Only
Read Line Pnnter POrt Status
N3me:
Port Address:
Access:
Description:
DISKIN"
0F0H
to
0F3H
Read Only
Read Disk Control Aegisttrs
Pon OFOH "" Disk Sl3tus Register
Port QFIH .. Disk Track Regisler
Port 0F2H '" Disk Sector Register
Port 0F3H '" Disk Data Register
Port 0E8H '" Modem Status
Port 0E9H
co
N.A.
Port 0EAH .. UART Status Register
Port 0EBH '" UART Receiver Holding Register,
Resets D.R.
BIT 7 '" BUSY
I-True
0"'False
BIT
6 -
OUTPAPER
I-True
0-False
BIT 5
=
UNIT SELECT
I-True
0=False
BIT4 = FAULT
'-True
0"'False
Name:
Port Address:
Access:
Description:
RS2321N"
0E8H to CilEBH
Re3d Only
Read UART Registers
BIT
7
thru BIT 0 ~ ASCII Byte
10
be Plinled.
Name,
Port Address:
Access:
Description:
LPOUT"
OF8H
Write Only
Line Printer Output Data Pon
Name:
Port Address:
Access:
Description:
RS2320Ur
OEBH to 0EBH
Write Only
UART Control, D.1la;
Modem Control; BRG Control
Name:
Pon Address:
Access:
Description:
BIT 7 thru BIT
Q
Name:
Port Address:
Access:
Description:
RTCIN"
0ECH
Rl:!ad Only
Clear Real Time Clock Interrupt
Don't Care
OISKOUT"
0F0H to 0F3H
Wrile Only
Write to Disk Control Registers
Port 0EBH .. UART Master Reset
Pon QE9H '" Baud Rale Register load
PortOEAH .., UART Control register and
Modem Control
Port 0EBH
=
UAAT Transmi"er Holding Register
Port 0F0H • Disk Command Reginer
Port 0FtH
0:
Disk Track Register
Pon 0F2H '" Disk Sector Register
Pon 0F3H • Disk Dau Regiuer
15