Spectravideo SVI 318 Service – Technical Manual page 91

Da t a S e t Rea dy ( DSR ) , P in 3 7 :
i s re a dy t o e s t ab l i sh t h e commun i c a t ions l i nk and t r a n s f e r d a t a w i t h the
T he DSR s i gna l i s
INS8 2 50 .
be t e s te d by t he CPU by r e a d ing b i t 5 ( DS R ) o f t he MODEM S t a � Reg i s t e r .
1 ( DD S R ) o f the MODEM S ta t u s Reg i s t e r ind i c a t e s whe t h e r the DSR i np u t has
changed s t a te s i nce t he prev ious r e a d ing o f t he MODEM S t a t u s Reg i s t e r .
No t e : Whe neve r the DS R b i t o f the MODEM S ta t u s Reg i s t e r changes s t a t e , an
i n t e rr u p t is gene r a t e d if t he MODEM S t a t us I n t e r r u p t is e nab l e d .
R e c e i ve d L i ne S ig n a l De t e c t ( RL SD ) , P in 3 8 :
ca r r i e r h a s be e n de t ec t e d b y the MODEM o r d a t a se t .
MODEM-con t ro l func t i on input who s e cond i t i on c an be t e s t e d by the CPU by
r ea d ing b i t 7 ( RL S D ) o f t he MODEM S t a t us Re g i s t e r .
S t a t u s Reg i s t e r ind i ca t e s whe the r the RLSD inp u t ha s chang e d s t a t e s ince the
p r e v i ous r ea d ing o f t he MODEM S t a t us Reg i s t e r .
N o t e : Whe neve r the RLSD b i t o f the MODEM S t a t us Reg i s t e r changes s t a t e , an
i n t e rru p t i s genera t e d if t he MODEM S t a t us I n t e rr up t i s e nab l e d .
R in g- I n d i c a t or ( R I ) , P in 3 9 :
s i g na l ha s be e n re c e i ve d by the MODEM or d a t a se t .
co n t r o l f unc t i on input who se c ond i t i on can be t e s t e d by t he CPU by rea d i ng b i t
6 ( R I ) of the MODEM S t a t u s Reg i s t e r .
in d i c a t es whe t h e r t h e R I input h a s chang e d f rom a l ow t o a h i gh s t a te s i nc e the
p r e v i ou s re a d i ng o f the MODEM S t a t u s Reg i s t e r .
No te : Whenever t he R l b i t of t he MODEM S t a t u s Reg i s t e r chang e s f rom a h igh t o
a low s t a t e , an i n t e r r up t i s gene r a t e d i f t h e MODEM S ta t us Int e rrupt i s
enab l e d .
,
Vee
40 :
P in + 5-vo l t s upp l y .
,
V5 5
P in 2 0 : G round ( 0-vo l t ) re f e rence .
D a t a Termin a l Rea dy ( DTR ) , P in 33 :
t h a t t he INS8 2 50 i s r e a dy to commun i ca t e .
a n ac t i ve low by EE£ g ramm ing b i t 0 ( DTR ) o f t h e MODEM Con t ro l Reg i s t e r to a
h i gh l e ve l . The DTR s ig n a l i s s e t h i gh upon a Ma s t e r Re s e t ope r a t i on .
Re que s t to S end ( RTS ) , P in 3 2 :
t he INS8 2 50 i s r e a dy t o t ra n sm i t d a t a .
ac t i ve low by programm ing bit 1 ( RTS ) o f the MODEM Con t r o l R eg i s t e r .
s i g n a l is s e t h i gh upon a Ma s t e r R e s e t Ope r a t i on .
Whe n low , ind i ca t e s tha t the MODEM or data s e t
MODEM-con t r o l func t i on input whose con d i t i on can
Wh en low, i n d i c a t e s t h a t t he d a t a
When low, i n d i c a t e s that a t e l ep hone r ing i ng
B i t 2 ( TER I ) o f the MODEM S t a t u s Re g i s t e r
When low , inform s the MODEM o r d a t a s e t
The DTR ou t p u t s ig n a l c a n be s e t t o
When low, i n f o rms t he MODEM or d a ta s e t t h a t
T h e RTS ou t pu t s igna l c a n b e s e t t o an
4 . 58
The RLSD s i g na l i s a
B i t 3 ( DRLSD) o f the MODEM
The R I s i gna l i s a MODEM­
B i t
The RTS