Radio Shack TRS-80 Service Manual page 29

Name:
Port Addren:
Access:
WRINTMASKREG·
0E0H
WRJTEONLY
Name:
Port Addleu:
Accen:
DRVSEL'
OF4H
WRITE ONLY
Bit 7 .. Undefined
Bit 6
=
ENERRORINT; 1 enables RS·232 interrupts on par-
ity error. framing error. or data overrun error.
II
disable above.
Bit
5
= ENRCVINT; 'enables RS.232 receive data register
full interrupts,
a
disables above.
Bit 4
=
ENXMITlNT; 1 enables RS.232 transmitter holding
register empty interrupts.
a
disables above.
Bit 3 .. ENIOBUSINT; 1 enables 10 Bus interrupts.
"disahles above.
Bit 2
=
EN RTC;
1
enables real time dodo; interrupt,
"disolbles above.
Bit 1 .. ENCASINTF; 1 enables 1500 Baud falJing edge inter·
rupt,
o
disables above.
Bit
0"
ENCASINTR;
1
enables
1500
Baud rising edge inler·
rupt,
o disables above.
Bit 7 .. FM '/MFM; 0 selects single density,
1 stdl!cts double dens' tv .
Bit 6" WSGEN; " .. no wait states generated.
1 ..
wail states generated.
Bit
5
= PREOOMP; " .. no write prec:ompensalion,
1 .. wrile preoompenSillion enabled.
Bit 4 = SDSE L; Ii scle<:ts side a of diskette.
1 selects side 1 of diskette.
Bit 3 .. Drive select 4
Bil 2 .. Olive select
:j
Bit 1 .. Drive select 2
BIt" .. Drive select 1
Name:
Port Address:
Access:
CAS IN'
0FFH
AEAOQNLY
Bit 7 '" 500 Baud Cassette bit
Bit 6" Undefined
Bit 5" OISWAIT (See Port 0ECH definition)
Bit 4
=
ENEXTIO (Sec Port aECH definition)
Bil 3" ENALTSET (See Port aeCH definition)
Bit 2 '" MODSEL (See Port ClECH definition I
Bit 1 .. CASMOTORON
(See
POI1 (JECH definition)
Bit 0 .. 1500 Baud Cuseue bit
NOTE: Reading Port GFFH dears the 1500 Baud Cassette
interrupts.
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