Spectravideo MKI, Сервисное – Техническое руководство, Страница: 91 / 134

Dat a Set Rea dy ( DSR ) , P in 3 7 : When low , ind i ca t e s tha t the MODEM or data s e t
i s re a dy t o e s tab l i sh t h e commun i c a t ions l ink and tran s f e r d a t a w i t h the
INS8 2 50 . The DSR s i gna l i s MODEM-control func t i on input whose con d i t ion can
be t e s te d by t he CPU by r e a d ing b i t 5 ( DS R ) of t he MODEM S t a� Reg i s t e r . B i t
1
( DDSR) o f the MODEM S ta tus Reg i s t e r ind i ca t e s whe ther the DSR inp u t has
changed s t a te s ince t he prev ious read ing of the MODEM S ta t us Reg i s t e r .
No t e : Whe neve r the DSR b i t of the MODEM S ta t us Reg i s t e r changes s t a t e , an
i n t e rrupt is gene rated if t he MODEM S t at us Inte rrupt is enab l e d .
Rece i ve d L i ne S ignal De tect P in 38 : When low, indica t e s that t he d a t a
ca r r i e r has be en de t ec t e d b y the MODEM or d a t a se t . The RLSD s i gna l i s a
MODEM-con t ro l func t i on input whose cond i t i on c an be t e s ted by the CPU by
rea d ing b it 7 ( RLSD) of t he MODEM S t a t us Reg i s t e r . B i t 3 ( DRLSD) of the MODEM
Sta tus Reg is t e r ind i ca t e s whe the r the RLSD inp u t ha s changed s t a t e s ince the
previ ous rea d ing of t he MODEM S t a t us Reg i s t e r .
Note : Whe neve r the RLSD b i t o f the MODEM S ta t us Reg i s t e r changes s t a t e , an
inte rrup t i s genera ted if t he MODEM S t a t us Interr upt i s enab l e d .
R in g- Indicator ( R I ) , P in 39 : When low, indica t e s that a te l ephone r ing ing
s i gna l ha s be en rec e i ve d by the MODEM or data se t . The R I s igna l i s a MODEM­
con t ro l func t i on input who se cond i t i on can be t e s te d by t he CPU by rea ding b i t
6 ( R I ) of the MODEM S t a tus Reg i s ter . B i t 2 ( TER I ) o f the MODEM S ta t u s Reg i s t e r
in dic a t es whe ther t h e R I input h a s changed f rom a low t o a h igh s t a te s i nce the
previou s re ading of the MODEM S t a t u s Reg i s t er .
No te : Whenever t he Rl b i t of t he MODEM S t a tus Reg i s ter chang e s f rom a h igh to
a low s t a t e , an inte rrup t i s gene r a t e d i f the MODEM S ta t us Int e rrupt i s
enab led .
Vee
,
P in
40 :
+5-vo l t s upp ly .
V5 5
,
P in 2 0 : G round ( 0-vo l t ) re f e rence .
D a t a Terminal Rea dy ( DTR ) , P in 33 : When low , informs the MODEM or data set
that t he INS8 2 50 i s ready to commun i ca t e . The DTR ou tput s igna l can be set to
an ac t i ve low by EE£gramm ing bit 0 ( DTR ) of the MODEM Con t ro l Reg i s t e r to a
h i gh leve l . The DTR s ignal i s s e t h i gh upon a Ma s ter Re s e t ope rat ion .
Re que s t to S end ( RTS ) , P in 3 2 : When low, informs the MODEM or data set that
t he INS8 2 50 i s ready to t ransm i t d a t a . The RTS ou tput s ignal can be set to an
ac t i ve low by programm ing bit 1 ( RTS ) of the MODEM Control Reg i s t e r . The RTS
signa l is s e t h i gh upon a Mas ter Reset Operat ion .
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