Model 111 Po Rt Bits - Radio Shack TRS-80 Service Manual

MODEL Ill PORT BITS
Name:
Port Address:
Access:
WRNMIMASl<REG*
0E4H
WRITE ONLY
Bit 7
=
EN INTRO;
0
disables Disk INTRO from generating
an NMI.
1
enables above.
Bit
6
=
END RO;
0
disables Disk D RO from generating an
NMI.
1
enables above.
Name:
Port Address:
Access:
RDNMISTATUS*
0E4H
READ ONLY
Bit 7
=
Status of Disk INTRO; 1
=
False,
(i)
=
True
Bit 6
=
Status of Disk D RO; 1
=
False,
0
=
True
Bit 5
=
Reset* Status; 1
=
False,
0
=
True
Name:
Port Address:
Access:
MOD OUT
0ECH
WRITE ONLY
Bit 7
=
Undefined
Bit 6 = Undefined
Bit 5
=
DISWAIT;
0
disables video waits, 1 enables
Bit 4 = ENEXTIO; (i) disables external
10
Bus, 1 enables
Bit 3
=
ENAL TSET;
0
disables alternate character set,
1 enables alternate video character set.
Bit 2
=
MOOSE L;
0
enables 64 character mode,
1 enables 32 character mode.
Bit 1
=
CASMOTORON;
0
turns cassette motor off,
1 turns cassette motor on.
Bit
0
=
Undefined
Name:
Port Address:
Access:
RDINTSTATUS*
0E0H
READ ONLY
NOTE: A
0
indicates the device is interrupting.
Bit
7
=
Undefined
Bit
6
=
RS-232 ERROR INT
Bit 5 = RS-232 RCV INT
Bit 4
=
RS-232 XMIT INT
Bit 3
=
IOBUS lf\JT
Bit
2
=
RTC INT
Bit 1
=
CASSETTE (1500 Baud) INT F
Bit
0
=
CASSETTE (1500 Baud) INT R
Name:
Port Address:
Access:
CASOUT*
0FFH
WRITE ONLY
Bit 7
=
Undefined
Bit 6
=
Undefined
Bit 5
=
Undefined
Bit 4
=
Undefined
Bit 3
=
Undfined
Bit 2
=
Undefined
Bit 1 = Cassette output level
Bit
0 =
Cassette output level
21