Digital PDFs

130-101-041-00

June 2010

25 pages

Original

16MB

Document:	RSX-11D I/O Operations
Order Number:	130-101-041-00
Revision:	0
Pages:	25
Original Filename:	http://bitsavers.org/pdf/dec/pdp11/rsx11d/RSX11D_Spec_Jun72/130-101-041-00_IOoperations_197206.pdf

OCR Text

. Rsx~110 SPEC
.
.

!"'••---------

ro1

RSX•l.1'J Oistprfbutlon

f"f(OM •

H, xreJcf

Jun 72

OATEJ 26

suqJ1 1/0 0 P ERA T I O~' S

ooc;

13~-1~i-~41-~0

•I

·Tne ,,,atarfal fncludcd Tn this +'wr'ct.fona1
s p e c f f T c ~ t T0 " , I n c I' u r1 r n g b u t r ~ t I f m r t ~ rj
.to,
l"s-t:rt,Jctlon tlr-i~s ano
ooera'tlnJ
s c e e ~ s I s f o r I 1 f o I' :!1 a t i o n o u ,. :J ,., s e s o n I ~' •
j

.A 1 l

suci1 mater J a!

nctfce,

~Itnout
f'\O claJm

is sqojec t

oh:,nga

Conceauently OEC

arij sna.11

not oa

m~kes

1·1a:;,le for

jts

accur·acy ·,
lJ n I' e s s s o e c I f J e r.l
a t ti e r w f s e ,
t n o t e r~ s
'' RS X" a fl d " HS X• ! 1 " 1 "" p I' y " RS X • 11 :-'\ '' 1

I NTRC!iJUCT I CN
·~--~~------~

The

RSX•1l~

c1 e v t c e..
suoPC'rt.

an a

I/n

st,uctwr~

f lJ n c t I on --

st~nrlaro

ls Ir.tended to provloB a f l~xTtle
I n a o ;:1 on de r. t l / O cap~ b J I I t ~, th ;"I t c "n
cef'lChP.r~ls

PDP•11

w~ll

o.1~t1ci'.ll

exreetea th~t usgrq wj l I d~vql0P
trig Ir
r,ur:lf.'SC device nandl ln:-i soft\·J~lro, rlr",..
t~e
P~ X
I I 0 ~ tr u ct LJ r c h J. 5 b :) en . d ~ s I ~!"I e ci i.: {) on~. k e 1i :i·11 I er.-~ n tat I n n
o f I I 0 s e r v r c o a s c I e a ;i
•1 n d
s t r a I g h t "" f n r "''a r a
a s r. o ~ s f c I e
ourp~se

u~vfcAs~
own ~pncial

CwTt~tiut

jAooa~orzrn~

~yst8m

l~te~rit~

afflco~c1>~

Perloneral devfce suriport Is NOT an fnto~ral p~rt of ~~o ~5X
axec ~ t I v € '
I t r s .:> r 0 v I Mg :j ~ y ,. Li r I " t I ~ CJ ~ j Tq_ ~ ~ s " c r\ I I A j I I c
H~ndlar TusKs, whlcn m~~ uo doveiopaci or modlf!o1 ~itn~ut ~n
lnt1mate ~nowjege of t~e exacu~Jve code,
1/0 reouast.s are ·1'~de t.o logfcal I/0 units, nnn art:> ~1roP-d
1n t o on y s f c a I c:i e v ( c e • u ri I t
r ei f e r e n c c; ~ v I a ~ ~ e t ~ f '' ~ ') v f c J
n s s ( g n,,, e n t s '' ·,
Ea c h T a 5 k 11 a s I t s o ·I# n s ~ t o t a s ~ i t"J n .., a n t ~ , ;, n d

J/O OPERATIONS

PAGE:

... th e y . ma y t.l e c h a ng e d e f t

i a r b y t h e~ Ta s k I n .e x .e c :J t Jo ,., , o r t r om
f TTV>°'1

-the ooer'ltorl-s console

f I t

n s r u. c:; I n g t r.e s y s t o m ( v I a SY s t 9 r.i
orrectf ve)
t.o
OUf.!Ue
I/0 r .~r.iuest for an Jndf cate:J L'}N
( L. ng l c a I u ~ I t ~ ! u m~ e r ) , . I f t h e L Lt~ J s ~ s s I ~ n ~ d t o a n h y s Tc ~ i
unTt, and ff the t-i~nnlo Task.to .i n1poort that 11nft is .,,e.,,ory
An I I O ni q y e s t I s "a d e

Y
n

resident and lnltlallze , the reaLest Is queued
J TasK~s briorlty) In a
r
a I u n I t • . '.:

. f~sual !~
the
recJestJ
· fo
t h c I n d ( c at a d o h ~' s f

by
nrfo~lty
re14uest Ti st

The ijSX ~xecutlve does ot attemot t~ f nteroret th~ the
reauest,
Jt ~n1 · y ~a~ AS ft to an t/O Handler TasK p~r L~~
assl9nment, an~ tne rlls osttfo~ of the reQuest fs a functl~n
cf t~e H~ndler Task (net t~e exec~tlve>,
2~

~than ·

a Task,
control
is
upon Ta5K nr(orlty 1 ·· ~f
c o y r s c > t o t h a r e ::; q e s t r n a T a s K , a n d t n a t T~ s K ?, I wrH' s n n s t ~ e
np t I on o f
s u «s p e n .j I n g o x e c 1J t I o r :·: y ri t I ! . c o .,, p I a t I o n o f a n I I 0
re o u tl st, or op~ r·a t Jn g ~ y :i eh I' o l"I o us ! ~(,
an"t/O

reQuest

fmmedfatgly

r~tu~ncd

oue1.4Ad . for

(contfngnn~

1/~ co~Pletlon may ~e fn~lcated T~

any

ootf n~~I

three

f o r ms • ·
( t ) . An r v e n
F I a g r:i~~Y b e s o e c f f I a 1
t o be sq t
Ca e c Q .n ~ l n I e d b y a d e c I r 2 t I o n o f a S l 9 ri l f I r a " t r~ v e n t ) ;l t· l / 0
c o mp I e t i ~ n ,
T asK
P. x . c ~' t J o n
ma ~
be
~ u s p c n d e d < u s I rq t "' e

· WAJTFO~

~irectJve>

combfna:fon

unt I an Tncilcatad EvPnt

Evef'\t

fl"-9S•

Fl~~.

(2)

t,n 1/0

1~qle1i
st~tus

sot ~t co~plett~~ nf ~n
oe
c I ear·e rt
b ~ f o r e. ~; u e u P I n ~ a
e n e c . e d o a ,. I o d f c a I I ~· , < 3 > a Sy '' t ~ :n T r ~ p
s e r v Jc e
r o u t I r. e -:i a y f o E I ri c u o e o f " a T ~ s i.: wt' I c n w 1 I I
f.n t e r r u p t t n e T a s K ' s e e c u t I o n u o o n I / s c o T. p 1 e t i o n ,

word

m~Y

spec(f fa

ls set,ClJ

ope r 'a t I o :i ,
Th I s
. r e o u e s t , a n ~ t 'i e n

wo r .

may

oe:v Ice: . I

:·1cEP(i~f)£'ICE . f

~--~·-----------~-1J n f ts,
I IO
r ~quests a r a made to LOG Ir. AL
~ 'i I c :i
e q u 1v a I e :i c P. d
t o
D Hv S I C A L
d e v I ~ e .. u n l t s v t a a '' L o ~ I c a. I

a,. e
' 1n J t

( L u T ) ·,
L o a r c a I uri I t. s a r e r r. p r e 3 n n t e d o y L c ·~ t ": J. I ' J n I t
r s < L L' N s ) , a ri rl e a c r L UN I s r e ci r e s ?. n t e n o y a n ~ n t r v Tri a

T a h I e ''
~: u l"1 b e

Un[t
Table" <U:il,
i~l-\yslcal
0P.vlc;e-1.1riltc;
are
reores~ntoc
by
entir t os l M a tab I e ca! I ed tl"\e P~1y; l r:a I ·,,n rt
I r e c t o r y P D > ·,

"~o;Tcttl

.. . . . .
······-········
~

-·

C1 J Tne wA t TF" aR n I r e c t l v A ~ r o v rd e s an '' oR " c o m~ I n a t ·1 o n ,
a s e r I o s o f wAI Tr O~ s p r o v I Me s a 11 '' A ND" ,

·a ,, d

I I n 0 PERA Tl 0 ~J S

PAGE

Tha

looJcal/ohysfc~I

~UNs

to · ohvslcaj

e~ulvaf ences

are

made

"ASSlGNJng

oavTce-~nJts,

wh e n a l. 1JN Ts as s J g n ~ d t o a p r. y s J e a I d e v J c e • 'J n I t , t h e
corasponif ng. ~UT entry (5lotl Ts sot to the ~ddress of tha
corres~ondfng PUO entry,
When

~LlN.

d~as~lgned

<assfgned

t~e

eorresnonafng ~UT slot Is ze,oed~
e: a e n Tn s '<

ti a s

o wn l- o g 1c a T lJ n f t Ta o I e w~ J c ti

Tt s

I s a o a ,. t

t rte Ta 5 K' s d i s I'( r :na i; e that J s bro u oh t t n to mP. mo r y \1na1 ~ v _or a
TasK Is FIXE1 or whenever ~ ~o~~~IXED Task f s run, ~owave~,
a
Task~ s ~ vT I s not "'°' f th I n l ts v I rt u a I a o 1 res c; '5 o ~ c e •
·~ ri P"
an 110 reawest Is ~ueuad (via tha ~UEU( I/~
Glr~ctlve>
t~e
i o ll u e s t I ,, g t .l s :.c t s 1... u T c I n r.i e ""o r y ) r s u s a n t o c e t ~ r ,, I n o ·.- h i c h
r> nys l c ~, I ~ 1:1 v I c io. - ~ n f t 1 s t o o e r f o r:t\ t h e r e oye s t , a ri d c o " t .... n ts
of an~ o~ner ~UT Is lrrevelant,
Tn e r e

i. r

~ ' ' o u r rn e c h an I s rri s f n q s X -11 O i n wh l c "' t ri a s e I f.' c t 1o n
I/~ 1evlce·u~lt can be alterea,
T~ey arq as

PHYSlC~L

f o ·1 I ow s.

·- ~hnn a Task f s INSTALLeo (MC 0

l~STALL

I n to

aatcM>
a" :J t n ')

t na
n y rn b c" o ' L'..HI s
mav he soeclflnd~
Assign~antq
to devlcd-unlts ,..lthot.Jt r~sloent 1•arialer Tas,~ M-,~

assfg~ment
~QT

s vs t e'",
of

eac~

f I a q g P. o ·,

REASSIGN ... Thfs

'~CR

runctfon al l~ws a· Ta!=il.\ 1 s i:ilsl<

resldant assfgn~~nts to bo ~han,e1, Asqiq~~entg
t () d e V f c i .. u n I t s ~ f t ~ o 'J t r fl s f ci e n t H a ;'1 a I e r r a s < .:; A RF
f I a; g e d '1

A5 S I G"i.! ... .. Th I s DI r e c t l v e (.\ I I' o w s a Tft s ·~ t ~ c ~ a ,, ~ e
I t s .,., e 'Tl o r y r ~ s l J a n t ~ \.J N a s s i 9 nm e r. t s , t. s 3 i 9 ., ' ~ c n ~ ~
to devJca~u"lts without resident Hanoler T~s~s AR~
f I ag9 e o ·,
RE0 t r< ECT • •

T\i f s

~· CR F" u n c t f c n

a I I C\ .-1 s ALL

1narc~tnd
?HYSICAL
redlroctad to anotn~r t1HYSI:::.:..1...
~n

r e ~ lJ e s t ~

~ov1ce-u~1~

bP.

cevlca•u.,it,
T~iie;
r 'Jn c t ' 0 n
Ts
I ,, t 9 n ,; e d
t0
s G ,, " e
In
cns 0
0 f
p i'l r T p :... e r a I f a 1 I tJ r o , a. ;i c tJ o a s " o t " r o v I d ')
n o r ~ a j 1v

uqeful devjca lncicJennence because the
ts lndapanaent of Tas~ or LU~,

A TasK~s L!JN

assfg~ments

m3y

~ade

re11r~ctjon

Joth before

and

~uri~g

P r e ... o " e c u t i o n a s s I 9 n "!'I c n t s .,, a y h e ~1 q ~ ~ f r f'.l "l t "" e
-1 at c '°\ ) t ") .. ~ I n 1 ! , a~ a r u r'\. t I r:i e ~ s s f ci n ~1 c ~ t 'i
.~; v
~o
ma1e fr~m tn~ a~ocutln~ Ta5K~
Howeve~,
exco~t t~r the
R~nIRErT M~R Function,
tn~re
Is
no ~aans of ~~tarn~! ly
e x I! c u t ' o :"\ •.

~1 C~

< or

Ch~n91"9

the

{/O

d~vt~e~unlts

u~ed

Tas~

unc~r

1/0 OPf.RATtONS .

PAGE:

1/0. RE:OUESTS
~---~--~---~
110· roauasts are ~ade ~Y T~sks usfng cf the~ ~n~ hnUEUE I/J
p E~
TAsK As s t G~ j 1"1 r::: NT 0 I RE c T I vE" I 0 , t r e .. Quc: :! c I I 0 p ;:- R ~· r R
ASc;IGN~l~lT
DIRECTT.VE''t
These df rectjves are
ldatiti::i:
e x e e.o t
f o ,. t h 'l ~ iJ 'l a s s i <i nm e n t s u s e d t c .., a ~ t n ~ I o 'J i c a I u r. i t

Into a ph~~rcal unft~ The for~~,. uses t~e r~skls own LuT,
and t~e latter tussrl tQ communicate ~Ith ~ne o~n~ole
op~rator> uses the MC~ Dfs,atch T~skls ~UT,

t.:nen a c.i•.JC:UE I /0 D Tr oet Ive Is f ssu~d, a en eek rs rnaoe to s~e
Tf t h ~ · I I O r e ri u o s t c a n b e q 1J e lJ. e d C~ J ·, I f I t c ~. n n o"t , ~ '"' G
O I ,. e c t I v a 5 t a t s ri C' r d
c ft a o u e s t c r ' s v I r t u ~ I
1. c r o )
I~
sP ~
neg.atlve

l'Indicate

reJoctlon,

the

~nd

n~gat.lva

v~•·1a

lndlcates the cdusa for reJectro~.
If the 0~EU~ I/G
n I rec t I v a I s a cc e o t e c'f , a r e q lJ as t n" ae t s for~ a 1 an .; I n-; e,. ; e c
lnto tMEl t""e O('IV I CP.•tJn rt! s reqyest Queue, . . n~ llarid I er T'1:~ I
f f l d 1e , I s t r t ".:'I g e r q d l n t o s e r v .r c ~ , a"" d t ri e r ~ cu a ~ t" r s
Directive status word
jc;
set· riosltfve C+~l to
ln~ica•e
1

oeforrr.~nce
of
th~
St~t~s 61oek may oe

DIRECTIVE.
s~~clf led

Cafspos(tf nn> nf the I/O

t.vent

set

~n l/J
co~-letion

r·IClg ;\rid
up~n

roQ~ast~

Is a separate I/O reQuest cue~e f~r oacn ohvsT:a1 ·
· devfce·u~1t,
These oueuas are oeQueq ~Ith their I 1st~ea~s
In the P'.!J antr~ for the corresoondlng p~y5ical devlcs•'...:nit,
The~e

1/0

r~q 1 ~asts

al'o

cunued

:Hf:>rlty

..;Jth

the

rPQUe~t

at tn~ rr~nt of the aeoue,
equ~I
prJ~rrtv
aFe
l~se~tea
Tn tn~ order
,eo~ests are made,

·orJopjty

Tne

QUEUE

I/n

OTrectfves

are

Jndlcate~

~J;i,~st

Re~ue~ts

the

whlc~

DJr~ctJve

I d e nt I f I c a t f o n Co rl a s
c'J I cs > •• ·:"! 1 '' ( f o r o J e ' : c ~ e r T a ~ -< ' s
ass I g n'"" e ri t s ) a l"'I a '' J 3 " c f o r QI.) e u e c ~ r .-1 cH as s I g ri ;a; o ,., t s ~ ,
·" 1 th
a 'i I ' e c t i v a Pa r a,,, e t a , Q I o c I< CDi-> S ) o f t h e f o I I o ·,! I n g f o r ~ :i t :
1

-:o··-~--~-··-:--~

t 2 ) Tn ~ r e n r e s e v a r a r r e "l s o n '> .,, h y a n ! I O r e o u e s t
c a r' n 'J t
~e
flueueai <1> tn'3 fn-ilcattt'f \,.UtJ ooP.s not e'X· l$t, <2' ti"li! L.J'l Is
n o t a s s I q n ~ o t o ~ r" t• y s J c .l I IJ n I t ,
( 3 l a H =l n 1 1 c r T a <; ~ t o
servfc~

the

onysfcal

conditions for quoyJng
fo~

the

re~uast

Mavle~
soe~lf led

r~sra~nt,
(4' tke
not '!'et;, or .C5> :.i nJ1e

not

~r.re

ouPue ts not aval,Rol·e,

1/0 O?ERATtO~S

w1·, 00 ... DIC (~1 or

& CE:F"NJ,
.. 1/0 F°tJnr. I co rte,
Cnueufna conCJI
e2
... (Prforlt!f·J
Wd,
Unused Bytl!l,

Wd', 21

~M,

911!'"!

LU~

~3)

0'1

t ·ron~J,

04
05
Wd, J6
W'Y, ~?
w~.

I/O Status 1-?IOCl<J,
#1,
,.,
Par:\meter ,,.,_,

--.....
~~

Wd,

C.Ad~ress

Par?.met~r

#3,
....-Htf, 13. ...
J. 2 ·Wd .- 13 ... P::iramoter
Wd~

Par~'Tlet<H
Par~m'3t~r

P~rameter

~~.

Par?.met~r

#4,
#.5,
~6~

1;7.

The OUCUE

~lrectfves

I/O

aro

doserfbeo

t~e

RSX~110

"OlRECTIVES SPEC",
1/0 .f='U~~CT I riN

COD~~

'
- .
--··-····-·------·
.

\-lhl le the' ~xacutfv~ does not lntarcret F'unctlon roda-:;,
ft
does
rcco9nrze trie re·__, r1rder tiirae bits of Al.LI/~ F'ucntl~n
Codes as tl"ie fol lowln~ "~u11ct.lon Atrfeutes";
Bit·~
9Jt~l

•• No RPturn ru"ctlon,
••

Bf t-2

r~Si,V~J,

reserved,

''No Pet urn" 1 v n ct t "n I s or. e I n ~ h I c n no ~ t =\tu s or d .a+ a f s
r e ~ u e s t o r , I :i t h e s e c ~ s e s , l T..i s k l"i n. y a u e •. •e
'enuests a"~ EXIT hefo,e t~ijTr co~plet!cn wlt~out fnvo~jng
lit".' Rur"ar.n'4"',

'•A

r e t u r n o d t .., t n~

T h o 1' o I I o ~" f n g l s a I Ts t o f I I 0 F" u n c t l o !"'I co 1 e s r o ~ o ., n I z c o
"' y
e o,. mo n· rt an .:f I er Ta s ~ s ',
I t J s not a com;) I at n ! I "t o r F' J" ct i ., n
Co d e s C An
Ha n d I e r T a s t.<
11;, ~
r e c o o '' z e a r1 y f lJ n c ~ I C· 11 ~ o ~ a
d o s I r e '.'.1
o y l t s t ,n ~ I e ,r. A I"\ t e ,. ) b u t r a t h e r ~ 1 I ~ t o f ~ o d a ~ u s ~ o

whare daviced
'Hl104ti J
0?0421
Z?l0Jr0

ln~e~enaence
~RITE

LOGtC~L

Is feasible

RECORD (LINE,

?RI'-JT F"ILF
11 E A0

L. uG I CA L

r' E C0 r~ 0

RF. A0

~JI Tr!1ui

ECµO

CJ~1r~t
~~140~
~ Ol 2,, J ~?

OF.CT Ar.H

tJ~24~JQ

ALL~CATE

~·~3 ·~~,,

UEALL~CAl~ ~iSK
Tn A ~ i ~ :: En I '~
LOAO TAS~ IMAGE
T~ANSi:-ER cu~

.zi~3~,J0

~~34J1
· ~H'' 4 ~ il -~

l'H'l4,.,,,1
J.J t.
• i"1

~H~440'i
~r5~k)0

ATTAC~

U~lT

CL I ~1 E >

CTTY)

TQ TASK

u·· ! T rRO~~ T.\31'\
~!SK

and practrcoa~

srorAG~

STORAGE
•~

REC0H~ TA~K !µAGE •~
OPEN rlLE FOR l~?UT
OPE~ f I~~ F0R OUT 0 UT

PAGE

l/0 ClPERATtONS

. ile'5400

CL.GSE: FI l..E

~~6~~0

OJ::LEH.: F'lL,E

Z~64eZ'

RENAM~

Flt.,E

·•• Exec4tfve functions
onty 'or executTve 1

perfor~ed b~ dfs~

~rJver<s'

1/0 STATUS SL.CCI<
:

~.-·-~·----

-.. ---'"'.'
stat~s

is desf ~ed, the ~ddress of
StatuJ · ? I ock ls I ncTuien f n the Queue I 10 O~d, . Th Is
·.Block eonststs. of two w~t'JS of the fol loiA1fr1g for.,,atf
Wheri 110 comolotfon

Wd~

P•

St~tus

Value

110

c-t~tus

a Unused ~vte,

· Wd'1 ~1 ~· L~rigth of tr.ansfer <In ·byt~s) f,.,r
READ/~RITE .function~, and ct~vf cg
d a p a·n d a n t i ri a i I o t h 9 " c a s e s ,
T h e f o I I o wf ng f s a I Ts t
of
v a ·1 u a 3 ,
A I' I
p !'.'l s s I b I a
Dartlcu1~r

Ha"dlor

are

ocvrc~,

Ta~K

~hat

c o :Tl~ o ,., I y
r e t IJr n e ~ I I O ~ t .1 t ~ s
s t !'!\ tu s v ~ I J e s I' e t u r n ~ d f o r
a
d1scrlbed ln the ~SX Spec for
t~a

serv(c3J 1t 1

A posrtlve vajua Tmol Jes successf~I
c"mo1etlo~,
a11 a
n o g at I v e v a I iJ A I ,, p l I e s r ~ j e c t I o n , o f t a J ! u r ~ , Tri 3 o o ; i t I v e
v a· 1u e r e t u r n e a I s 11s 11 a I I v e 11 a < + 1 ) , h o t\! e v e ,.
o t ;, e r
oc s i t i v a
v a· 1u a s n a ~' b e u s a d 1 v I z , , TTY Han a I H Tas k I '1 e n t f f l e ~ ".:' ., ~
AM tarmlnatlon on Jnout 1 tir'\d 'U & •S term("atl~n on outoqi:·,
·.99

UNRECC'GN12E'J f"UMCTION
p~ VAL. t 0 An G~ ~ CS S

• HJ
.. 20

p.:vAL.tD PAf.i.\71F:TErHS)

•30
au~UIN~

UNIT

AL~EAOY

~~CHANIS~

. ..
. ..
------·-----~---~wh q n a" I I r; r e ri u e s t Ts

formAa

ATTACHEO

~n1

fn~ertAd

Q 1J

a 1.1 a d f o ,. a Lu "J , a r e Q t I e s t i' o i s
re~unst I 1st fnr
Ll.'N 1s ~ss i gneJ 1
T"'e f :n ~at n f

ov crlorlty f" the

dev Ice-unit to wh I ch the
' e q u e s t "' o d e I s a s f o I I o '" s I

Wd 1

. .... for\'1al'd ITnkaqe,

~,,
,

~~ rl ·• "1
fJ rt ·• J2
wd '• 03
wti ' P4
fl d I 05
~~ d ·,

Wd 1

~6
'tj7

....

----·-"!.

I I "kag•,
STQ adcr css · c TasK I ~n '

Backwrird

A TL. noae ~di' of r~q!~estor,
Prforfty & lln~SP.J ·8Ytu
LUN & £ F" ~~ '
IIO Functf ori "ona,
110 Status ~3joOi< il d d r P. s s,

rs
:~e
t~a

PAGE

l/O ' OPERATtONS

Wd ·,

~C'J

Wd·, 11
Wd ·,

'
Paraliieter #11
Parame:ter #·2,
P~- ramel;P.r #3.
P:\rnmeter #4,

--.......
~·

wrl. ~2
Wd '1 ~3
~4

P'.'.lr1.meter ;:.5,

ii rf'1 15 ••

"'d ·,

Afte~

P~rametar

... f'l r:ime te r 7',

;J.6 t
f;

no~e

In Jnsertcd 1~ a ~evJce~u~(t~s r~nue~t
Tl!it, the four <orlowJn., ooerati'lns c~use, or aj.-t, t~e
· or~ce~st~g of th~ !/O rea~csti Ci> the H~ncl~r r,s~ts Event
F' I a g on P.
I s set, ( 2 > an "I I U Re oy a·s t -s !! u 0 u a a Co .1.J n t er '' c f CJ r
t nq un J t > f s
l n c r ~ me n t a t1 ,
( .:.; '
an
•~ I / .J
R ~ a 1J a s t .-;
P ~ i\'1 I "' g
Co t.J n t ''
< f ,.., r t ~ e r 9 a u a s t l n ~ T a s k ) t s i ., c ' e r,1 e " t '3 a , C~ J a :i d ' 4 > ·

a reQuAst

a Slgnf flc1nt Event Js oaclare~ 1

~hl!.ln ;s.ii !/'J Ha,,dle, ·Task
1s fdle1 . ft tssugs :-\ W ·UTr~R
Of r e c t 1v e . ·" t t h Ev e n t F I a o o n e ~ o e c f f f e d ~ s a ri cu s u ;. , I I y , i; h ~ )
Evant r1Qg whose settl"9 s~oul1 cause 'esu~ptlon o' H~M~l~r
Task
exec! l t r on •
i h us ,
~n
J d ! e Hand I ~ ~
Tn st< l s tr J t1 g 0 r ~ o
fnto serylca by the oueing or an IIO rAqu~st for an~ or the
unf ts ft s~rvf oes,

Tne 1/0 Reieusts Qu~ue~ Ccuntar rs a word Jn t~e
PUD a~try
o f t h Ei u "' I t ~ o r. wn r c h t h o r e ., u e s t wa s ~ u e ti " ~ ·,
T"' ·J s c o t' n t l s
J ne r e :r, e n t e 1 f o r e v ~ r y ,. e ~ .. ~ P. s t t h !\ t ,I s , u e u " d t or !. h t' u ,, i t ,
a nd
l s o r ' v i d A d f ., r H r:t n 1 I 'H 1' a s ~< u s a ; i:' • ·' o s t Hn n '.j I '=l r T , s '.o(' s
do not use It,
but
some
s:ec J a I
pu r Q~s~
aric
..,u It l -u,, ft

Mandler
Tasks
can onarate more ~ff lea~tly ~tt~ t"f~
f a o I 'I I t y ~.
T}"I e co i..I n t m~ ~· o e a I t e r e d h './ t :i e ~~fl n d I ~ r Tcl s 1< ~ t
any ttrrie·,

. Tno '' : I O " ~ c; '1 a s t s
of every aetJve
daere~~nt~d
e r.i u 9 s 't s ·•

T ti f s

memor¥ ff ft

no ~ e

a"c
I/C

u s e :1

~XIT~

ATl..

This ccunt ts ln~re~enterl
nn lndlcaticn of
pending

"'o ',Jn -t; "

Tas~,

provide

ri e n c; I n g

a ~ o " c:

t ~, 3

:j e I a y

a'orted

w~t~

t n t h ,.,

f r e c i n 1J o f r a ~ ~< ' s
u~satlsf Je1
IIO

ve,,ue~ts·.

OunulnQ an I/J
po ~ s f h I "
Task ~I"\ an I t

Task>,

r~quest

c ~ u s e f o t'

l s ot a

ts a Sl;nTflcant

T~araror-o,
l Sl;nlflcant Eveit
an ?/O reouest ls Queued,

w~enever

£v~n~

~eca4se

T-3. s '< ~ w1 t c tl J n 1 < r ~ s 1 1-, :' t I o n .,·f H 111 _.. i ~ r
h I 1 n er
"r f or r t J' "= ~ 1 n t ;' o re ;Jut? >:J t ~ r
weolar~t(on

~a~~

...................
,.
~

...

t f a '' '' o ~st urn'' tun ct J o,..,,
Tn e r a :n A nt o .j ,

C3)

RP.~ u est s Pa,, d l n g co~ n t

l s ;J'H

PAGf:

110 OPE:RATtONS

~--~~-~-

....

Un :i e r ~ S X- 11 ~ 1 I / 'J I s s u o p o r t o d h y " p r J v f i' e g e d Ta s k s '' c a I' I P. c
l/
Ha " d I o r
T a s r< ~ , C4 J
esa
Ta s k ~
a r e c ~ I I e d r. r i v I ! a y c d
b e r, a" s a t r1 t-i ,y h ~ " a ~ c c e s s t o ( l ) t h e P ri tJ - 1 t
C: '.< t e r ~ a I P ~ ~ ~ ,
(2) tho exl~cutfvets lists arid tables, :ind t3l routines w.,o~e

misuse cou11 lntgrfere w1tn norm~I
svste~
Prlvf l~ga~ r~~~s are trustee not to ddStroy t~~
wn1ct'\ t h a y rt,111 ,

·tpnr~tlo~~
sy~tem

Und~r

' l/0 Hari~j3r Tas~s conststs of two $ectJo~ss
(1) A "'ask
:'l r d
( 2)
an " I n t e r r u p t s e r v I c e r ~ u t I M e " • T n A Ta c:- r<
Tevuf oortlon Of ~" !/O HanaTar Task rt.Ans AS a norm~I r~sk,
with
its
o~n
co"taxt,
and )~ a softwar~ or~1~1~y
muttfproor~m~t~g anvf rnn~ent~
Th[s part of a riandlar Ta~K
gener~I Iv
lnt9rfaces wit~ t~e exec~tfve
(viz, 1e~~eues
reciuestsl ~"1 oerforms the bulk of tn~ 110 servlca,
Th~
rnt a r r ~J ;J t s e r v I ~ ~ ,. o v t r n o p a r t o f a Ha n d I ~ r T ::i s k r u " ~ .1 ° r
haruwara ~rr~rfty (as~nchr~nous to tne ~oftwar~ nrlorlty
mult1pr~gr~m~in;
~ystem> Jn resoo"se to a pArloheral rlevlce
Tnterr~ot,
IntarruPt service routines ru~ In a no5itlcn
rndt:ioendcnt
e"vrror\i11o"t1 an\j .goneral IY dO as 1 lttl~ as

· T Q v e "! '' 1

t> o s s f .., I

e·,

Handl·er Task na~as are dictated by co"ventro~ so t~at t~~rr
"'e'" o r 'I ,. e " I d a n c Y iil a :I b 13 c o r'l v P. n T e n t I y c ci n t r ".' I ! e ·1 , Ti' ~ n ~\ ~ e:·
o f an I I 0 ~'a n d I e r T a s "°" a I w::t y s c o n s J s t s o f
a
t ~~ o
ch a r ac ~ er
. s 'i ,., b o I f c
~' e "' I ,, h e r ~ I
n ~ ,..~ e
f o I I o w e a ~ v f o u r cJ ., t s < p e r I o rl 3 ' ·,
Viz,,

Tho ·1andler Task thclt sy .o ports JT.; t~ru iJT"

ecll'lec

"0 T·, ·, • ' n ',
A I T H i1 ri I d "H Tas k s
(at
I e~ s t
aI I
t hn t
o o n t :\ I ~
f n t P. r I' •J " t
s e ti v I c a r n u t r ,, e s )
s n o u I d "' o t b a o e c I a r e d " c h e c k n o I 11 t l r. I e. ''

wh~n

t~cy

Jre INSrALLad Jnto a syst~m,

~l~o,

~Jst

~1n~1~r

Tasks vs e t i1 ~ i ,. l n l t T:} ! I z at l on code f o" st~ c :i< st r r '°'· g ~ ~ c :;\ c ~ ,
and
t n er c f o r e
silo'-" I'd
o$
de c I a r e o ~· i'i o t
F I x a o 1 a ·•
"",,en
INSTA~l.erl,

Ha" d ·1 e ~ T~ ~ k r es T d ~ n c ~ I s con tr o f I e o
Functions,

Lo Ml .. - Th ! s "' c R ru n c t f o n a I I o ws
c~u~e

I/O

H~ndlor

l/O r'lc:uec;ts 1

soeclly-ln'J
OT.~P1CD) 1

t ~e
an

f o I I ow f n n

o :i e r a t o r

Tasks to bacome rearly to

rlnridler
s~mooltc

Tasks

se~vfcA

afl'e . lndlcata'.1·

p'lrrol"\eral

.'·i CR

cvlz ••
~ay
also

na""es

A partition a"d/or Priority

. .
.................
"'
.

The . st~tem dlsk driver fs a pa~t of tho
assembl~, ~ut apooars as a~ 1/0 Han~[er Task,
[~)

executive

1/0 OPERt\TlO~S

bA spoclf Jed, ff a Handler Task cannot be loaded,
· a reJ9ctron messaga fs output.

UNLOAD

This MCR Functl~n ~! to~s an o~~rato~ to
o~uso
~n
l/O Handler Tas~ to c~ase to sGrvJcg
reqyasts wnen Tts request o~euc(s) are e~~ti,
T~ls, of cour~e, frees up me~ory,
·~

Wnen a Har"dl.er TlSk

1oacted1

tts~qt

friltfallzes

l~a

fngtruots the system C~AITFO~ Di,actlve> to sus~end Its
e x A \) ll t t o n 'Jn t I l an I IO r e ~ye s ~ i s Q.u elf e d
f ~r
t e
Hi:i n -t l P. '

Tasi<·,

1/0 Ha~dlar Ta~kS are suopf fMa~teo by two sets ~f ~a~ory
,eslr.lent r9•entr!:lnt subrou~lnos: Ct> a HandJ~r ·T:ui-c lfti-rary1
ano <2> tne S~sta~ S~orouttnes 1
·
Tna·Ha~dl~r

~l~rary

c 0 n fl !; q r !\ t r 0,,
r.io ' r~

to the
bl

( s:; 2 ~d ,

Car not

sof jstfcatco I/O service',

oct< i l"I g'/ u"' b I o ck I r; 1 ,

Library

cra~ted

~u~t

· OA

er~ate1)

and p , 0 v l d as I' i) u t I ,, ~ s t h,a t
a e c es s

re ... cntra~t,

n j?.

vr.z,,

ni ... tho d s ,

at c ,

but

r"ot

5Y~t~~

!'\ r ~

r. ')..., ":1 ·':H1

str'JC::.;re

TI"' a
11 :l n i I ~ r
necl'3sSlir ly

Po,ltlon·l~dapP.n1ent~

T h e S ~ s t n m Su o r· ou t J n e s a r e a p R r t ~ f t h e a " e c u t I v e a ~ s ~ ·n ~ I y ,
An'1
- ~lwavs
exlfjt·,
These
s1Jp-j'"o·(1t1nes
orovfde c;:.;fc
fu~ctlons, m~st ~f which a~e co~~on to
al I
rl~n119r
Ta~~~.
Viz~,

Rn 110 rAJuast noje, return ~ node to
I f s '6! e ! a =" a ~ t s , P. t e ,
T;., a u s ~ o f
b~ H~njjar Tasks ts a~scrf~ect late~.

~eauaue

a v (\ I I a ~ I e

~ubroutjnes

tn~

1001

~y ~ t em

a " o r f v T I e s 9 d Ta s t< " 1 s P~ S T ALL e d f r t o a s y s t a 'i' ~ t h e ~ S~
c on t en t s
f or
aII
but
t I"\ e Ta s i<
c o 1 .~ e t\ r g ..; a t e r mI n ~ j a "" o
tecoPded ~f th tfil.a Tas~ts disk !rnago, The cnntc~t~ of
t~e
ASR usoj for TAs~ c~de f 3 !et ~Y the e~ecutlva ~~an tnP Td~K
fs loade~ <oec~us9 the real a~~re~s sp~ce in ~r.1~n 1t f s
ro a o e d I s "" o t f I x e ; ) '1 Th e f c I I o ..., l ' g J ~ ~ d e s c r I n t I o n ~ f i ~ a
v I r t \J a I
a ':'l a r e ~ s · s o ~ c c
a ! I o c a t f o ri s
< As ;~
usa g e )
f cr
l 1O

~' n e ri

Hand ·1 er Tac; k

I e v a I e" :J e ,

Vf rtual locatfons 0~0000-017777 <ASR?) ~re use~
for Task
l~vel oocte,
:\iote, thfs code lf1 .1 jl"'ftac~

to · 4i\,

Vf rtuat locatfons

02~~00·~77777

(!~Rs

t,~,1)

Virtual

1~J70C•157777

(~S~s

4,5,6)

a'e
u s o rl f o r e x A c u t f o n c f ~~a,., a I e r ~ I ~ r ~ r '' r o lH I n a s ·,
Note, the Han~ler Llora'Y Is I J~iteM ~o 12~~

used

l~catlons

to Rccass the ~~6eutlvafs tao la~,. ~fsts,

Subroutines, ~ote ~·
pool,
a"d S~stam
e x c a e d e 1 ?. K ·,

Syste~

t~e

tab!es,

S~hroutJnas

svste~

are
1~~

I !st3,
cJnnot

PAGE

1/0 OPERATIONS

V I r tu a I I o ca t Ton s. ~ 6o~c~·177 7 77 < ,\ s ~ 7 , . a r ~ used t"
access the PDP~11 E~ternal Paoe~
"'hf le fnterrupt servTce roytfnes are o"'!yslearl'/
Han-:llP.r

l/O

Tasks

(us'Jaf IY

a onrt of

oart

·~f

tiie s~rne asse 1rOly>,

·they are executed Jn Ker~el mode, and unrle~ the kernel's
ASR3~
ThYs 1 Jnt~rru~t servlca routl~~s are ~rltton ~s
oo~1tJon~Jndepqnrlant coda Co~
written to fun · In vf rt~~I
~ddres~

sp~CA

0600ZZ~~77777>;

The kernel address soace ir~0~~-177777 c~SPs 4,5,6 1 7) ~~1 ~n
1/ n
·;i a n d I e r
Ta ~ r< t s
( us e r
s !'.' a c e , · 1 0 ;~ " ~ ·~l .. l 7 7 7 7 7 a r e
eoTnol~ently mapoa~~
l~e,, The ex~cutlve'~ tablns, I j~t~, &
_. Sy ~ t d m ~ u o r o u t I n e c; ,
;\ n d th a e x t a r n a I o :1 g ~ :i r o a v a I I a ~ I ~ t o
T n t e r r ti p t s e r v I c e r o ~ t I n a s ( k o r n e I mo d ~ ) a s
we I I
a s t ..,
a
Ha" d l e r t. r; Ta s f< I e v ~ I c o d e ( u s o r mo. d e ) 1
.

~--··-·--··----~~-The fo! 1owlng PQP~11 program Is a samPld l/O Handler T~s~ to
s u pP o r t
a
s I n g I e un I t
d ·a v I c e c a l I P. a
" LP '' ~· h I c h ri r Tn i'. s
.. directly fro~ a reiuAstcr's ~e~ory,
The p~rpo~e ~f · ~his
s a"' P ·1e Pr., gr a~ I s to I I I LJ st rate lr1 a.id I er Ta~~ k ~on 5 tr u r. t i o"',
and does not repFasent o~tlmal cooe ~r a functional
rl~n11er
T a s k ·,
AI I
c (' c e u ,, I ., IJ e t 0
t ti e d a . f c a ( n 0 t p ,. e s ~ n ~ I v ~ "
exlstent parfpheral) n~s oeen omlttect, and In · man~ c~~~s
f

reg.lst~rs

~re

red~ndantJy

!oaded~

NOTE •• Thfs sa~ol~ pro1ra~ Is lnc1u~e1 for t I lustra~(~n
curposos
only,
It IS sxoected t~at c.~anaas Co~r~a";;
radical)
....,Ill
ba
:-:iaje
~s
Yanoler Tas!<
lmpjfr.i.a:itl.tinn
exoerjenca fs g~Tneo,
~hfs s~mil~ ~1 I I be reo1~ceo ~van
.a c t u a I l l s t l ~ g a s s a o n a s oosslble,
The

oro~ra~

Ts used as a~ ~x~mole for tne

re~a(nder

thfs

Spe:9

.
.
.
. . ..
~---~--------------~~-------~----···-··----·--·-----~-~----~
~

J GENERAL

R~=~~

R1=i'1
R2:~2

P.J:XJ
R •l: :'.;
R~:%3

SP: 1.6
PCs;%7 ·

R~GIST~~

DEFINITYO~S

I/n OPER~TlO~S

. J.
1 GLOBA~
1

(EXEC)

• ,DS 1.li

Jl''lt:r.L.~RE

,GL08t.

,,,STE.':F

;~ET

,CLOS~

; ~ E lW ~ UE1J E A~.! I I 0 .... EQ ~ F: S T
Ji\TTAr,H u~:1r
I ~ATP~
, , IJT~ 1 N J r. ETAr. H L,l'•l I T
, , l O!J~ J J I 0 ~ 'o 'JC:
~ • ~~TP J '.iPJ ~lO"JE TO POOL

SET.

• ~ cu::F ;~LEAR EVSNT FLAG(S) 1•16
EVE~T

tLA~CSl

1~t6

' • f)JQQ

,GLOtll.
-,GLOi:H..
,CL.OBL
. ,Gl.OtJL.

,GLOL>l.

, , F"i..SH
• ·, Ri~D~

,GLOS~

,CLOS~

1rLUS4 nwcuED l/O
i RU~J • D0 ·-~ t. DDi\ E

• ·• ! NTX J ! NTEP.Rt.'PT SERV t CE EX t T

·. · ,GLOB\..
. .1

REfERE~CES

I ·,

.·. ,GLOiJL.
· ,GLOBL,
.· . , GLOS~

SY~BO~

.11

c 1~J T JCONNECT INTERRUPT
, , DI~· T 1[l I scCl N;j Ec T t IT~ r\ ~up T

,·GL08l..

PAt;E

I '

RD I 0 J t D 0 p

! A5 K ~ b E H !G R~: i\j c0 wj-j

YIO nEOJEST NQnE ENTRY DEfTNITJO~S

•

R.T0:~4
R,P.P~J~

;SYST~M TASK CIRECTORV
;RE1U~ST PRTORl~V

R,~F"=11

;I... 0 G I C AL tH~ I f NU ~I P ER
; E VE 1~ T. F" L ..\ G ~PK 8 EC\

R • f"C::l2

1t/O

R,l.,U=l~

R,SA=14

ru~CTI~N

ENTRY 4QR CRE:Ql 1E.:ST0R lfJ)

COJE

; ,\ 0 r1 R£ S S ( VI R T U ~ L ) N" R E: J 1! E 5 Tr: R I I 0

R,PA:;ll'
;TEN•?YTE .REQEWST ?AriAMETER
J
J OI~ECTIVE PARAMETER B~acvs (O?SI~)
. J

Op91f

101,

J~ET•SYSTf~~TRA?

JPWR

PwRJP

RECOVE~Y

~ T A T US ~! 0

BLOCK

°D

us~o

~IC

TQAP tO

;SERVICE nourINE ENJRV

.J
l~a I

Op621

tO~UN

JSEiV~CE

J VA I RA8 L~ S USED
J
~

••

RQUTt\E (NTRV

r OR I ~ I I I .~ L I l AT I O~;
JFJEVICE
J
DEPE~0E~'T
I
VAqIAB~ES

'Z
0
~ T~ RT

DIC

J I I 0 RU \J 0 r. ~ 'l T R ..:~ ? t 'J

I
·

J~ET~SYSTEM~TPAo

HAi~ 0 LEr\ T.\ SK E,·~ T f( Y ,

ri A ~~ DLEii

I S I ~ I T 1 A L ! t :: ) ,

AN n THE I Nt Tt AL l 7. AT I aN c0 DE . t s n-: EN : ';:; [ D r c R
I STCiN.AGE,

sT A(: i'<

J PQW(R•qE~OVE~Y & I/O•RU~~QWN SYSTE~ TRl?e AH~ Co~NECTEO
9 THE SY<;TSM VIA "~ET ~YSTEM TPAD" 01KF.CT1V£S,
I
ST~RT~

~ov

#QP81,~CSP)

I./ 0 Cl P£ RATI 0 NS

'J 40,

·e:MT

377 .

~ov.

#OP82~~(SP)

f.MT

J77

J ~N ~NTrRqUPT
2
Ar-i
THE

SERVICE ROUTINE IS

CQNN~crcry

TR~~ ~QCA!I~N

s As r or T ~ E sERv I cE Rcu r p ·E: ' s Aa;; r~ E5 s sPAc E

:r ·ts SPECIF"IED AS THE HA~Ol,ER TASK'S VtRTUAL. tE:RO,

.J
J ?F THE

S~RVICE

CANNOT 8E CON~ECTED

R~UTt~E

(A~OTHER

1 I 1'H : RR UP r SER VI Cr. R0 UT I i~ E I S CCl ;·JN EC H.: 0 > , THE HA.\I :J LE R
I TA S K e: X t T f S 1·

...

MOV

#24~ 1 RJ
# t NTt.NT, K1

CLR

J TR.AP AOR TQ R~
J t.NTRY PO l 'lT TO R1
f8ASE OF AOR S?~CE

PC1~1Cl~T

rco~NECT

· '-'OV

JSR

EXIT

ave
.I

. 1 THE HA ~J aI... ER

TA s~

tOENTirICATI~N

DlSCON~ECTS

I s IJ Ec i.. ARE' D RE s I 0 Er~ T' A.JD I Ts u f.! I T
(UIT> iS INtTIA~I~E8,

f
J

EXIST, T"IE ~A~'D~ER

#UIT1R~ .

JUNIT ID T8L

~av

#11Rl
#"LPrR2

i NU~l RER CF' U lI T S T0 R l

JSR

r> c I ', ' Ds!I T

MQV

ave

A~R

TO R0

JOEVtCE NA~E Ta
JuECt.ARE & ~ET

DAE:X IT

,
lNITIALI~ATION ~rCULIAR TQ T~E PERl?~ERlAL

9EING

T~SK

EX!TS 1

~rov

.J .

JCXIT IF Nir CON~ECTAa~E

lA3~E

. I
J It NO u~~tTS ~OR THE DEVIrc:
~

TO ~2

IS NOT

S~?PORTEO

DEVICE

SHO~N,

·1
~JQP
· . NOP
~OP

P1EV I CE

DEPE1~0EMT

INlTIALI2ATION

f I N1 T t AL I 2 AT I M, CCMP !.. E TECl • ~ ! ~~ S TR lJ CT J Q'; '.5 A'I D D.\ T .\
f PRECEJ t ,'~ t; Tri I ::) L ~ C.\ TI 0 M ,'1 RE ~·! 0 L 0 NG'- R ' : EF. DC: 0 , P" E
~ HAN CH~ Eq r ..4 S
S :j TACK IS EXT E~~DE D T J UT ll. I T I t E
r nn s s r a:~ A GE ·,

·<'

I
MQV

PC,SP

J HAND L, ER TA 5 i< 1S ~' 0 W I 0 l., E A~JD RE A0 Y TC'1 f'J t: •Qt' EU E R~QUE~ TS
I
I THE l.4A"!~hE1i TA 5 K I S EXEC~ T I 0 N IS SUS PEN"." E'J L' NT IL. ( 0 P
1 IJ NL Es s ) t Ts Ev ENT F"L. AG 0 ~! E 1s s ET I

·r

1· THE T ASK . WI LL R~ ~' A t N S'J Sr EN0 ED U~: T l L A~l t / l.I R EC!~I C.: S T t S
' 0 uEuED r~ R 0'! E 0 r THE I.I ~n Ts sE~w t c£D Gy THE ~ ~ N0LE'~ T As~

f (A JNIT

lDE~TIFI(D

~HE UIT>~

1/0 OPE:R4TtO~S

P4CE

t F" A SY S TE M TR.\ P 0 CC IJ RS

t..: HI L. E

T;.H: TASK I S ''1 A I T I NG F' 0

' t/0 RE~U~sr · ro ~E QUEUEO, THE TRAP SrRVtrE ROUTl~E
f 9E EXECUTED, sur THE TASK WI~L RFMAI~ SUSPE~OED,

:t3

° H~

~!LL

101..e:a
.

~ov

#~F1,~csp)

Cr-JT

377

f~AITfOR

E.r~

J TAS~ EXE~UTlON HAS ~ESUM~D BECAUSE ITS EVENT fL~~ ONE 4AS

; 9EEN

sr.r,

' THE EV«:~ T n.AG t 5 CL..E:A~En, A~·~D M: ATT· E~'PT TO OE·~U~ur.:,
.J ·A R~ 0 UE: S T F" R0 M \J ~! l T• ~ <T HERE t S CNl,, Y C~: ~ U~11 T ) l 3 v, Ar'I t: ~

1
J

·I

I f A Rr. cuEsT I s nE.. Q 0 EuEn t I T ? s p ~ 0 c E5 s ~ u ·,
~(UU~ST

DEl"l

IS NOT

O~·QU(UEO~

r~E

~av

UtT•0 1 Rt7

. J,Sq

P~ 1 ', , CL.Er

J PllD t: 'I TRY .~o ;-1
·1F"t.AG INO TC F\1.
IC I., EA~~ Er:- ~1

MQV

~!T+i,RC'J

J"U~J ! r- ~~

~'OV
JS~

pc, f' t r.i Q q Q

BVC

IDLE

#11R1

I F"

QECO~E5

IDLE;

r
· ~tCV ·

HA~D~~~

#~NA,Rl

1n ~.1 A dUF'

E.~TRY

PU~
A!;~

T! R1

A01 TO

~,,

1-. TT A a., P 1

J D~· \1UEUE

JlCLE lf

rn RJ

~~J

Ct:•QUEl.IE

SEaVICE COG~

CONT~OL ~s DISPATCHED Ta APPPOPRI~TE
~/0 F'U'lCTIOi\ CODE, ~ITH THE RE--uEST ~ror;r_:

ADO~E~~s

PE~

p; R.l",

J I F' T "'4 E. Hr. QUES TED F UN C T I 0 '! C0 0 E I 5 NC T R ~ I"" 0 G1'H l!: ED ,

; I/0 STATVS VALUE er .99 lS ~ETU~~£0,

,, ~J

I IO F' U~'.CT IC N C8 0 t. 1 :J R2

\1 OV

1r1 F" C ( R 1 ) , R 2 JS ET

~MP

R~,~~4ZA

3 EQ
CM?

fJ r n1 E~
i y Es - • tJ R'!' r E l I .. E
f·<::~,#14Z~J
J•"n ·- ATTC.Ch n::""Et1.;;T7
ATTP~~
JYES -- ATT~c~ IF n[T~~~F.D
R2 1 # 2 ~~ 0 '11
J 1\ 0 • • DE Tf, Cq . ~~ (=1 u ~ ::: T ·1
~ETRE1
JYES •• OETA~~ ir ~TTA~H~J
R2,#•177771fi'~O ... ti4 : ~0L~;1 E'<IT q::;1...1 ~~T?

AEQ
CM P

REQ
CM?
8 Ea
~

JMP

E'< TRE1

# 'fl! 9 9 1 , R o

(WRITE PE:~ESr7

J YES • • F' I ' ' l S ,..; S Eh '' I C E & S X I T
J ~ o - - uN.. ·:. · Er. or; N t :: t:: :1 r- '} ~.; c T t o'·'

uNSLIC

I WRtTE PEOUEST •• THE STARTING AQnRES~ A~n LE~GTH

o,; n.: ,

1 ·.a r pi E L n; ~ r o s t •,; R IT Ti: ~' AnE v~ L I
~
t F o1< Av ,
J THE i.. I '1 t I s PR J.'~ ,. Er1 , i F" No r , A i ~ i / c 5 r Ar us v Au1 ~
J or •10 1s RETUG~ED~
J
~RTR(QI

NOP

JVALl~A~ION

YET

1/0 OPERATtONS

PAG'"

NOP.

IBE OETER~INEO

' £VENT rLAG TWO IS CL~AR~r, THE ?RlNT QPEqATIO~
ST~RTE'J,

EXECUl'InN IS SUS?(\JQED 1;~Tl~ EVEi'~T
' 1 F"l.AG THO Is SET (BY INTERRUPT SC:RV I CF.: q_9ur I NE,.,
I .
. Pri;
J REF'ERENCE PO I MT F'OR PWR rA I l, R~COVE:fH
>J .
UIT-k0,R~
J'CLZAa IMT~Rf:'!UPT fl,AG.
MOV
I

AN~

·JSR

#21Rl
PC•'• ,CLEF

'JOP

JOEVICE

~av

;·

NOP

~OP
-~OP

;

fF"l.,AG H~'.:1 TJ t\1

1· CL.~..\~ EF'

DEPENDENT
CJOE TO
START I/O

e:,r-·. #2

~.~ov

;,t:,Jf2,··(SP) JwAITF'OR

,•

E;MT

377

Pf"2:

IRErERENCE POI~T FOR PW~ FAI~ R~COVtRY

J ~ e: au f: sT t s F' t NI :) ~ EiJ 8 y sr.: TT Ir-' G THE RE: Q'·I c: ~ Ta R, s .
I t/O STATUS ~o~o (IF° SPECIF'tE~>. AND E~ENT FLAG
1 CIF INDICATED);
.
I

or.vsrs,RJ

~ov
BP~

SIJC

i_p~~uc

1~ t 1CCC: ~ S F9 U~ C0 t1 ? LE T l 'J ,\i ?

J YE S .. .. RE TlJ :~ :-J 3 T A T US :: • 1
JNO ••.RET~R~ ~£VICE STAT~~

J
J · AT TR E Q .. .. UN t T 4c: ATTACH E0 T ~ RC: CUES TI~! G TJ\ S ~ CU\; L. t: SS
J IT ,IS At.READY ATTACHE;J TO IT> I
J
JiJ~HT-~ PUO ENTRY ~,QR TO R,..
UYT+~,R~
~ov
ATTREQI
JSR
Pr•', , 4 TUN. JATTi\CH UiHT
1 I~ ~ ucc Es~ Fu L. q ET u ~! s Ts=+ 1 I
S1 !C
svs
#
..
J~,
.~3
JOTHERWISE, ~ETUPN STS=•30,
.MOV
RR
U-JSUC
J

J nt:TREQ ... UN t T 1 s OET At:HF:O F'R0:-1 REQUEST P'G TA SK ( u~JL.ESS
J tT IS )JOT ATTACdED) 1
I

OE:TREa;

~av

UtT•~,R:J

i U•: l T - fJ' P t,J !'."' E :..;. TRY

JSR

Pr;,', !OTUN

8VS

sue

JCETAC4 lJ:"dT

~ov

#.3::t 1 ,R3

JlF SUCCESSF~L, QETUPN STS:+1,
10 THE R~JI SE 1 ~ET U~ r-. S T"S ::- 3 J ·,

A0 ~

T 0 R1

u~~suc

f
J

EXTR(~

EXTREQI

•• HA~O~~q TA5K EXIT
~OP

fDEVICE

~OP

J
1

~JOP

DEPEW1ENT

REOU~ST

cooe: ro

••

C~EANUP

& EXIT

I/0 OPERATlO~S

PAGE

15.

TERMtNATE U3.~G~

~OP

1· OE:CREMCNT RE:~JESTS ?EN'JPIG COUNT A~D RETUR'J ~ECUEST ~'O'JE
J.

"1QV

R~~A I"< 1

CL.A

· MOV

#1•RJ

Pr. 1 ",,IO~N

J~R

MOV

RNA,R1

Pc,;,RN!P

JSR
I
, OAf:XIT~

(REOt!E:5T ·\WOE

#240,qo

~ov

J sR

,. .

Pc , ', , n PJT

TO Rt

1110 QONt:

(REQUEST ~nor AQR TO R1
JRT~

NOOE

JOlSCO~NECT

t ..

AO~

JNO DECREMENT hOJ
. JSTi\TUS TJ R3

?00~

& EXIT

fTRAP ADR TQ

Jo Ts co ~:NE c'!' t Nr ERR u,, r

EX 1TI

JEXI~

..,
.a sue ·'
sue;

MOV

51, 1 a(SP)

!'.:MT

377

HANDLER

TAS~

JEXlT CIRECTIVE

r?NIS~

~ov

S~CCES~fl!!.. REQ~'EST 1

~ET

I/C 5TATUS IS

TO +1

tt+1,R3

I
I l_fNSUC

UN~UCI

R., 1 A1 R1

C~R

·JSR

1rlEQUEST
J ;\C c~. TS

p G' ', I ? OON

J'l/J

~ov

R" 1 A' R1
PC,', ,RN!P

fRE~UEST

J':R

•.

'f ., RNAI
J

~~ov

t s cLE A Rr. 0

THE I/O

~U~JOWN

J RT:J

~'J

.·~c~F.:

a DR TO R1

? "u AC'J
..~,,OE '\OR iO

~jOCE

POOL

r 0 . r ;\ ') I c,.\ TE " ~! ~ RE Q l ' Es T DE- c IJ EuE" b,,
TRAP SERVICE RCJTIN~, .

; tr A,. T/ 0 RJ ~.: 0 0 .._ ,, s )' c; TE~ TR AF r. cr uRR i: D "~ H IL£ i HE
1 PP.ESE f\I T RE aUEST ~·AS IJ E - ;.i U E. UE Q, p; DIC ~ H: I / ':' q u~J •
J QC\,>;N COMPLETE 8Y ~ESIJ~P~G THE R:.J~!DO~·t TASK,

1
J

TST

SEO

~fJFl,AG

or:a

JSq

PC,·,, RNON

'SR

Ot:Q

POWER ne:coVEr?Y SVS'?'EM TRA? -- IF A. ~RITE ~-~S STAqT~J

ANO ~OT f l~lSHEJ, IT M~ST 8E REO~~E,

T,,

PAGE

: l/0· OPERATlO~S

1.·
•

PwRl)P f .
1

·' CMP.
BL.T

~SP 1 #Pt1

CMP

C?S?,#PF2

BGT

P~~rx

MOV·

#PF11@SP

Mov

fHh~(SP>

MQV
M0 V

Hl1~(SP>
VI T+ ~ , 1

MO\/

#2,.R1

JS~

~c,~,STEF

MOV

(SP)+,R~

~t·Hlt:X

•• 0 v

1· ' P F' 11 ·, t, E , P c ', L. E • ' P F" 2 e ? ·
(NO ~- EXIT SYS T~AP
fNO ·- EXIT sys TRA?
rrES -· CAU~( 1/0 TO 8E RE~O~E

(s p ) + ' ~ 1

. JS(T E,F~

PWREXJ
f ·.

'. l/O
f

'tonUNI

MOV

#XST,~(S?l

~MT

377

R~NOOWN

SYSTEM TRAP

~ ·a,,

fH-1,~(~p)

MOV
. JSR

#I.I I T +3 , ·~ ~ ·
.Pc,~~FL~H

· TST

R'JA

JEXIT SYSTEM TRAP ROUTtNE

frLUSH . QUEUED REQUESTS

. r

SEQ

IORR

r~ 0 V

H'! A , R0
R ·,·1 D ( F\ <) > , 1 ·, R0 I 0

CM P

ONE

IC'Rr?

INC

Rnf"LAG
IORX

r
Io~R~

JSR

lQRXI

MOV

HOV

EMT
J
TASK

'
wr2;
'
•

'
Wf"1;

.(SP)+ IR~

#XST, .. (S?)
377

DIRECTIVE PARAMETER 81,.0CKS
,BYTE

41 ', , ~

0kl00~1

,BYTE

~1. .. ~

~~2Z~2

XST;

103,

•I TASK'S vARIA8LES

· 1/0

CPERATtO~S

RNA:

IREQUEST NOOE AOO~ESS
I t I 0 RU ~JD nW~., F' L AG

RO~LAG~

' HAlH>L~ER TAS K' S \,p.1 I T I E'l TI f 1 CA T l O~J TA8 ~ E

O~· L. Y at H: UN l T1

. UIT:
·f
~

f NTERR up r .SE q VI Cr n 0 UT Yr~£ ~ .. P aS I T I O~J

r ( RU ·'4 S UN 1 ER K ER

:~ ~ L

r ~Et.. J w '~ s P r:l s s I RL~ , n 1E
1

ROUTINE'S

INTE:Nq

AOORE~S

~lQP
~JOP

RO" Tt Nr.

SPACE

s o n

SPECtFIEO ~HE~

s r' '·' c

co~~ECTEQ),

· I DEVICE
i
DEPENr:"El\iT

~!OP

MOP

I N'1 E P E~'a r. :H

WH I CH I ~ S t: T .q , J R ~ ~ CL 0 S ,- L V
BA E F"
1E p .· r r. r~ R P T
E I E

AS ;; 3 ,

. INTERRUPT

SERVICE COOE

----··---------------·------~-------~-------~--··---~·--~---

-··--·-----------·---·----·
HandTvr Ta!lk lnftla!Tzatfor1 consfsts of conn9ctlng to ~:/'1t"!m
Tr~ps
~n1
~ardwai~
JnterruotCs),
d~t~r~in1~0
~~lch
d a v t c- 3 • u n I t. s e x l s t.
( o f t t3 :i
o '' I y
o '°' o l
a~ d
h ow
e a c ""
ls
ldentlf fea, an1 declarfn1 the Handler TasK rosfdent nn~ 1b•e
to de•Ququo 1/0 P~Quests,
I I q Ha ri d ! e r Ta s k s n o r ma I I y 1,1 s e t wo ·S y s t e "' Tr .:i ::: s ,
p n "' P r
r eoo vo r y ,
and
I I c run 1 ·J ·~ n ••
Ti1 e s e ~ ':I s .t ·-i 'T1 Tr a ri ~ i.1 r o v I d u r~

me~n!

wha n o.ver

l~terruotln~
a ~a~dlar Task's nor~al o~ara~inn
Ct o ~1 er
I s r est or e d ( aft c
a o ow~ r f :i I I u o l , '-' r. d

PAGE

. Wh~ncve( a Task EXITS or Ts aborted wJth I/O reoucs~s
Pendln~. ·
The Systom Trap service routf nas are c6~necte~ ~o
tne ~~stem (as ara aTI ~ystem Tra;>S) using tna SET SYSTEM
; IF<AP'Olrective,
\

Most Handler Tasks reoufre only one :fnterruct service
.toytlne, however, as Many as are desired -~av exist wltnTn a
Hand!er Ta~k~ connectJng an Interrupt service routine t~ a
ha~dhare jnt~rruct is Instructing the s~ste~ (t) tn transf~r
cont~o!
to an lndfcated servlce routine
whenever
Jn
Tnte~rupt
occurs vfa an Indicated f nterruot tra~ aarlr~s~,
and <Z> where the ba~e of the (~terruPt service routl~e's
address s;:>ace ls to be set,
·
·
~._ A

S~stem SUbrOU\,fne

to connect to an

rnterruPt Is cal tad

~.s

.: fo .l tows:

...

c, v,

address,
.
Entry Point · of se,vlce rout In!,
Base of lnterruot servJce adaross s~aca,
Blts 0•3 prescribe tMe states of ~or~ltlon ~o~es
~, & N at entry to Interrupt servtce rovt'n~, ·

JSR

PC 1 , ·,CI NT

R1
R2
R3

-----

Interr~ot

· . ~ h e n t ti e c o n n e e t

·SET

~ p on

tr~o

1 s s u c c fl s s f u I ,

CC.. V ( c o n d f t l o ,, Co ~ a

!' \J '' >

uoon sucroutTne returnJ If unsuceessfu1, cc-v ls C~E\R
r e t ~ r ·~ ·•

In ~ost cases, when a~ (nteriupt service rout Ina . eannct

· c o·n n oc t e d ,

t h e H;\ n·rl I a r T as k e an n o t r u n , a n d I t s i 111 ~ I y ~ X t Tc: •

· Howe~er,

t~e
apor~priate,

c~ded

Handler Task can be
·
·

w~atevqr

o r o ri r am ,
t ha
Tn t. e r r L! p t
sArv I ce
r fl 'J t I n e
t n ~ '' t ! n T t I d e n t I f r c a t I o n Ta b I e " ( u I T > , h u t n o
ot~er cart of tne Tasx
outsfda of t~e Jnterruo~ s~rvl~e
roijtlne,
H9nce, tha bqse of the lnturrunt service routJ~e
could have bean set as high as fUIT'~
It
ts
se~
a~
t~e
Ta s k - s v i r t u a I z e r o t o s n o w t h a t : '' url I C3 s s a Ha n a I f1 r T 3 s k r s
lars~r than 4K woris,
lntorrLJpt · service routine
refere,,c~s
d o n o t r e s t r ( c t H a n d .I" a r T a s k I a 'i o u t " ',

t he

s 'l mo I e

r e f e r. e n c a s

Wh e n c o n t r o I
ASR3

set

J n t e r r ~' p t s a r v J c n r o ~J t r n '~ ,
sp~cfflarl "baso of Jntrt.rrvrlt

I s t r a n s f e r r a d t o an
as

the

se~vfce address spacen wf tho1Jt exc!udl~g Jt,
T0 cat 10 n ~ 6 0 0 ~ 0 c x s t s A t a 3 2 - w0 r d 0 0 u ~ d

To c a t I o n I ri d l c a t e d I ,,
AIl

li a n d I e ,. Ta s k s

I ,e,,

vf rtu:ll

(') r

b e I 0 w t 4'\ 6

R 2 ·,

. o r ov l d e

s on c o

f or

s y s t o rn • ~ e t

'' 1 1n 1 t

Idont(f Jcatfon Ta~le''•
TnTs tablo c~~5lsts of ~n~·wcrd
entrles for 9acn dovlco-unlt that t~e ~anoler Task c~n
se~vlcA~
words re~rosentlng non•exlsto~t untts . (no P~~

PAGE

f/0 OPERATIONS

eritr~)

are set to zefo~ Words racresanttn~ exfstlnn ~"Its
are sot to tne coresoo~dfng PLIO ent'Y adore~sos, The~e
addresses a.re norma Ir~ used 011 l.Y as
uri It
I tierit If' ers WhP.n
~ak(ng
reauests of System Subroytln~sJ ~o~ever, thev ~tso
Dr~vfde an acc~ss to a unf t!s PUO entrY, ~h(Ch ts useful
In
some soecf al cases~
_A System Subroutine to fnltlalfze thls table and dcc1·ar0 the
Handf'er T:isk rasf dant and read'/ to de•queue roQuasts f s
-Cal red as fo I lows!
R~ ~-

Oevfce name (two ASCII characters>,

Ri ~- MaxJmum numbe~ of units Ct•~l~ size>~
PC' '·, osyr

JSR

.. If at least one Py~ entry toi the soeef fTed device f s ro0n1,
CC•V fs SET upon sv~routrne return~ If th?. davJee name rs
not f o 'Jn d t n the PU O~ cc .. V I s cLE AR tJ "a,, r A t '.,' r n ,
The
Hanoter tabk ts f lagge1 resident In tna PUO entry for ~aoh
~nlt lde~tlfTad to the Handler Task~

IDLE
.
. STATE
. fOR HAN~LER
..
. TASKS

...

;

-··-------·---~------------
When a · Handler Task Ts fdfe, ft suspenos
..

an I/O
ls do~o
Event

Its exeC'!ytJori untf I

reQuest ts Queued for a untt suoported by It, Tnls
hy jssvlng a WAITFOR Of rectlve,
The HnndlAr Ta~K'S
FI ag

Its unJts·.

Range

1~16 1

one

set whanave r a

r oqwes t

f s. nunued f n r one

r.or"'allY tho WA?Tf"OR D~R lndlcate'1 Event ~l::ig
and f jag numbec one, ho~ever, Jn so~~ ca~e~ ft

may be dns1rable (and fs possJb.le) to wait for morn than one
Event FJag's setting~

·If a Powor Recovery or a

t/O

Rundown

Syst~m

Trnp

occurs

wh T I e a hand I er Ta s K I s 1d I e 1 the Ta s ~ w l l I r- s m.\I n s us.., tl n CJ~ d
'J n·1 o s s
t h e S ys t e m Tr a o
s e r vTc e
' ou t I n e
c a~' s e :l
It s

resumption,

1/0. REOUEST
PROCE~SING
.
.
.
..
.

r··-~·-·-···---~~-·~~-

Whan an Tdle Handler Task's executfon I~ ra9~med (as a
I e s u ·1 t
of
T t s E v e n t F' I a g o n e b e i n g s e t > f t n o r mci I I y r. I ~ a r s
that Flag before attemot{nq to de·~ueu~ a r9aue3t., (~J
however, fn some specfal cases Tt Is desirable to clear t,9
Queue Ffa~ ~Event Fla9 one) at other tfmes,

The CLEAR EVENT f~AG Dfrecttve could be used, however, sTnce
1

the

Pr Iv f I eqed

TAsk

has

~~stem Suoro~tlna· fmposes

access to the systamt s Ii sts, a
!e~s overhead Cana c~n clenr
~ore

PAGE: .

..1/Q OPERATIONS

21J

f fag)•,
A Subroutlne to e)ear. ~ny of a Handler
Task's
Event .F'. I ags ·1~16 f s ca 11 ed as f o t I ows l,
... .
',

than

one

.•

·R0 - ~· ~uo entr~ address
. R1 ~ ~ ~ I' a 9 s l n d Tc at o r ·,

(from UIT>,

Pq 1 (, C~EF"

J~R

. R1. bl ts 0•15 represent E\lol'\t flags 1•16 respec't;lvel~'•

110 ,eauests for an Tndlcated unlt a~e de•oueued bY usJnq a
· •ubroutfne to attempt to de•oueue a request node, This
:subroutine ls called as fol lows;

· ffrf~- PUD e:ntrY addPess

(from

UIT>,

R~ : • Ad d r e s s o 1 b ~ f f e r f 'H " RN A•! ·1 .
P9 e , ·, OORQ

J~R

If thfs subroutine Ts called and t"e l'eouest llst fer
fndlcated unrt Is em~ty 1 a request node Ts ~ot de~oueued Cof
.C. ou r s e > ••
A I s o , e v e n wh e n a r e a u e s t I I s t I s n o t e m~ t y , I t l s
PossJbla to NOT be able to de~Queue a reQuost because <t)
.the unit Js ATTACHed and no ~eouests for the attachlnq Task
are
Jn
tne I fst, and/op (2) 'eQuests In the 1lst have bafln
-made bY a Tisk
that Ts checKPOlntad~.
':......
~.

.When a request ls de~Queued, the RcQuest Node Address (RNA>
ts storeo Jn the ouffer f ndlcated ]n R11 a "Hecue5ts In
Process Count" Is
1ncrernented, C6J and CC-!V J s SET ._.Pl'.'n
aub~outlne pet~rnr
When a request Js NOT de~quouod, cc~v Is
~~EAR upon subro4~Tne return;

When a reQuest node Ts da•Queued, ·Tts address f~ set ff'\
tho
c al 1Tn g o r o g " a"' t s b u ff e r co o ; R1 , wl t " I n t e r , u o t s · 1n h r b ( t e d ·•
ThTs f s do~e so that a non~zero RNA buffer can be used a~ a
ti re Q lJ e s ~ d e !! Q u e u e d '' f I a ~f,

.. -

·1:91·~~---~--~~--

To avoid the race condftlon that e~lsts whon a ~o~ond
reauest f s queyed Just after a fal lure tt> de•Q\JOLJa h".s
~aused the Handler Task to become Jdfe agaln;
~5l

... .

· e··~~--~-=··"!'~--

~6] tf

"No'Return" . functfon, Requests Jn Pro9ross
NOT lncremented·,

Count

l/0 OPE~ATIONS

PAG(

'-1

The ReQuests In Pr~cess Count Js a byte Tn t~e AT~ node of
ever~
aetf ve Tas~~
This count rs Jnc,emented whenever a
Jequ~st fo~ the Task f s de•queuad, and decre~entad
Whenever
• reQuest for tlie Task Ts oompfeted,C7J rt provf das an
lndlcatlon of raouAsts bet~g orocassad, and Is used to delnY
the record}ng fswappf n9•out> of a cneck~ofnted Task untf l
·110 ln p,ocess has been compTeted.
No~mal ly after de·~ueufnQ a ¢eouost 1 the I/O
functlon Code
Ts exa~Tned, and eont,ol ls transferred to a routfne to
De;tor~ the indicated functlon;
tf the functlon Is not

tecognf zed

the

~Qnvent!on)

Handler

rs returns~,

Task,

stat~s

~99

(by

If an ATTACH reQuast Is de-Queued, aMd the unlt J9 n~t
attached (tn tne requestfng Task) 1 tne unf t Ts
flagged for the axclyslve use of the attachlnQ Task;
Thfs
causes the oa~quoue Request System Subroutine (,jOQRO) to
~t;eady

onT~ de~quaue

r'aquosts for tl'lat Task'1

A S~stem Sub~outTne to attach a unit ls cal ted as fol'loW5I

R0 ~- PUD entr~ add~ess Cfrom UtT>a
R1 ~~ Request node

address~

PC i , ·, /{f U.N

.J~R

When a unft Ts attached, cc~v fs SET u~on subrout1na ret~r"~
unlt fs NOI attached, cc~v Ts C~EAR uoon Faturn,

Whan~

•t a theOETACMrequestfng
reouest Ts da•aueued• and the unft ls
iask1 tne ATTACH ts nut llffed. Thls

atta~hed

.to

tha De•oueue Raauast S~stam Subrouttne (,,OQRn) to
d&PQ~eue
from the top (hfgh pr{orJt~) of the unlt's reqwest

~ayses

Tfst;

A system Subroutfne ~o detach
f o:t Io ws I
R0

f~om

unft

cnrled

PUO ent~y addfess (from UlT>1
Request n~de address~
P~ 1 ·, •4 0 TUN

JSR

When a ~nrt Ts detachodt

cc~v

SET ~Do" subr·outlne

ret~rn:

Whan a unit Ts NOT dot~~hed,. cc~v Js CLEAR uooM 1etu,n~
•

•

r'!'•::·-~~--~~-·
)

~73 U~less

"No Return"

funet1on~

l/O OPERATIONS
Man~ 1/0

requests peauf re a transjer ef the,

•e~uesto~ls

memory~

The

PACf;

f,om

of t~ese t,ansfers must be

~ange

·validated fn o,der to mnTntaTn system Tnteg,.lty,
·following three s~broJJtJnes ald Tn tt'\f$ operation,
A S~stem SUbf'outf na to vat fdate

18 .. blt

starting

~aTled

as fQl'lowst

address

Tho

transfer

l\nd

setup: an

(for a pe;loherlal' oontrolloP) Ts

R2 ~~ Flrst word address Cuser

v(P'~Uaf )1

R~ ~'!' f,tansf &I' Teng th (ln bytes),

PC' I·. VX[R

.JSR

·If the t~a"sfer Ts JnvalJd, cc~v Ts CLEAR ·~pon 5Ubroutlno
,etuPn 1
?f tne t~ansfel' ls valld1 cc~v ls S~T upon retur~.

rs" T" R4 & R5·, The 1 nw
the high O'der two bf ts are Jn
4 of R4 wTth al I othal' R4 bf ts olaa,edr

and- the 1s~b Tt start Tng address

16 bf ts al'e In R5,

~rde,

bits 5 ~

-S~stem Sub~ouilnes t~
Pe;for~ the transfer,

~nd

valldate ~ tl'ansfe~,
are eaTled as fol 1ows1

~nd

valid

R2 ~~ fTrst w~rd address.Cuser vl~tual>1
RJ ~~ Transfer Tangth <Tn words),
R4 ~- Memory b~f fer address~

'pc, ,·,al.,X!

.JSR

or
JSR

PC'

I·, 8\orXO

rer ~ransf SP INt

ror transfe~ OUT,

If the tia"sfer Ts Perfo,med 1 cc~v Js SET upon subroutf"o·
retu,n,
If the t;ansfer Is NOT pe~fer~ed, CC•V Is CLEAR

upon re~ur,,·,

When a" l/0 operatton fs oomof eted 1 an Eve"t Flag ~nd an I/O
Status Word ~ay be set CJf lndlcated ln ~eeuest ~ode)• t~e
'eauestfng Taskf s ?/O Pending Coynt fs usual IY decremonted,
and 1ts Reo~ests .. , ,, Progress CouMt Is decrementoQ, C8J
A S~stem Subroutfne to f lnlsh an 1/0 reQ~est

called

f0Tlows1
R1 ~~ ReQuast nodo ~ddress 1
R2 ~· Adjustment to unlty dec~eme~t,

~·

110.Status Block Wd,

110 Stat~s Btoo~ Wd 1

0~ 1

01~

·~·:"!~-~~··:~--

~Bl

If ~No Return" function, NEITHER. oo~~t Is altorod,

l/O OPE:RAT?ONS

PAGE

PC~ '· ·, I ODN

.JSR

If an t/O Status a1·orik address was sooof ffed l" t~e

reQuest

"oee, the status bfock <.Tn the ~eQuestoris memory) Js set to
. the

eon~ents

& R4'1

· tf a" Event Pfag numbo, was spacTfled In

··that event f f.ag Js s~t and a

~aQuest
node,
Sfgnffl~a"t EYo"t ls decJa,ad~
t~e

Tne J/O Re,uests P~ndtng Cov~t for tne

reouestf ng Task Ts
and then modJfTed by addf nQ ~he eont~nts of R2
t Q ·11 1 R2 l s ,, o r mri f TY z e r o 1 h o we v e I' 1n s om e c a s e s t h e
dacrementl~g
MaY be adJusted Cvlz,1 R2;•1 for rlLE OPE~ and
R2~~1 for PI~E C~O~E)1
T~e
ATTACK ~ DETACH subroutTnes
~Odlf~
a Taskls 110 P&~dTng count so t~at a reQunst Ts
c•Qn$Jdered pend l~g w~I IG a u~I~ Ts attac~ed to t~at Task;
decrem~nted

Wn,n an I/O

"orle Js "o longer ~eeded by a Handler
oool of aval labfe I tst efe,,,o,,ts·,
A System Subroutfna to re,ur" a Mode to the oool Is c~fJed

Task,

t~ ·fs

,e~uast

returned to the

•fl followsl

R1 ~~ Request n~de address~
J~R

PC 1 ea·RNTP

When a~ IIO ~pePatTon f s stafted whose termlMatfnn ls·
· •lonaled hy a na11dwaP'e IMterrur:>t; the 4al"ldl°or Task ma~ use
tne WAtTroR INTERHUPT Directive to susoend lts execution
un t I 'I th e Tn t e ' r u P t <o r a o P r o o r l at e s e i- l e s o f I ., t e r r u r.i t s )
has occurred•,
Nornal I 'J the ~and l'er Task! s Event
F" I aq
1;1t10
0
C2 '
I s v s e d a s a "' I ,, t e r r u ~ t 1 I a g ~· ', Th J s f I ~ g I s n o I' m:i I I y
e1ea~ed before startlng an oparatlon a~d set by an lnt~l'iuot
Sf~Y1ce

roUtfne to

Sfg~al

~omp!etJon~

A Subrout(rie to el ea; any ef a Handler
1•;6 (s cal ted as followsf

Task•s

Event . rTags

R0 i~ PUD ent,y addPass Cfrom UtT1 1
R1 i~ rrags lndTcator~
J~R

Pc, , ·,ct. E:r

Ri bT~s 0~15 represaMt £Va"t rlags 1~16
A SubroutJ~e to set

any of a Handle,

Task'~

''cat led "S fo1TowsJ,

R0 ~~ PUO ent~~ add~ess (from UlT) 1
R1 ~ ~ f" I' a g s I ,, d Tcat or ·,
'1 ~ R

Pc 1 , ;' s n: r

,espoctlvo!y~

Even' Plags 1~16

PAGE . 24

.1/0 OPE;RAT l ONS
"

blts ~~1~ rep~es~"' EveMt flags le1~ ,espectlvel~~

.,...

~~--~:--~~--~~

MANOLER
TASK
EXIT'
.
.
.

The UNI.CAO MCR functlon ls used
cause a· a Hand fer Tas~« to
Th l s Ts d o ne b y Q LJ e u I rHl a l o w c " I o r l t Y ~ a ouo s t t o t ~ a

i xl t '1

unTt represented

the dovrcels flrst PUO entry, and
Queuing by daclaf ln~ the Ha~dJ·a~ Task
non~Fesfdent (fn e~ch PUO entry)~
The 110 function code for
an exit ~&Quest ls 17777~ (~ctal~~ .
lnhlbft{ng

furthur

sln~le~ynft

'd evices, ~ervlcfng an 8Mf • ~eq~est
flnlshlng the reQuest c.~IODN & ;,RNTP),
dlsconnectfng from hardware Tnteirupts, an~ EXITlng;
More
~omplex Handl'el' Tasks reflulrll addftfonal code to p~oeess al I
· ~uau~d requests befo~e .EXlT("g•

In most

oo~sTsts

Jt cannot
reeloaded (the LOAD MgR ·r~nctlo~ wll I find It actlva>~

.S/0.

WhTle a Handl'e" Task Is Tn . t.,e ppocess of EXlTJng,

RUNOOW~~-

C'!'•~~1111·~~·

·When a Task EXITs or ls aborted wlth llO ,eauest~ pe"dfnq,
tna Task Ts consJdeped actfve CATL node and me~ory stf I I
• x Ts t > b u t n o t r u n;\ b Te , · an d a ,. e a u e s t t o " " u n d o w" ~~
l ts II O
Ts

made
Cvla
" ~ •• l 0 ·, ' " ·•

SEND

REQ\JE~r

oJrect(ve> to a Task cal'led

The 1/0 RuMdown T•sks l'eaucsts Handler Tas~s to f lysh oue~ad
;oauests 'and either f Jnfsh or abort a"'~ reo 1ests ln cP'ocess
1

an lndfcated Task~ by (1t elea~fng )ts Event r1ag ona,
placf~g
the- Taskf s STL node. address fn tha SCO~ word
~,RDI01 <3)
c~usfng
an I/O Rundown System Trac foi a
Daptloular Handle,. Tas~, ;ind (4) suspending lts execution
un t I ·1 J t s Eve n t F' ··1 a g ono I s s e t ·1
fo~

C2)

When tho Handler ·rask completes Tts t/O ~undown sorvtce, Tt
resumes the executTo" of the I/O rundown Tas~ b~ setting Tts
Even t El ~g o n e ·,
·
A S~stern SYbroutTne to set Even~ rtag on'l of a
" 1 ',10, 1 "
Js cal 1eci as fol lows1

Task

caTted

JSR PC 1 ', ·1 RNDN

'Tne l/0 Rundown Task CC:)ntlnues tnTs r>roccs~ untl r al'ther the
ReQuests PendlnQ Count fo' t~e Task hef nq rundown ls
do~,e~Antarl · to zer6, or al I devices have
beon scanned (ln
Whlchrcase somethl"~ Is wrQno, ITkel~ a bad handler);

PAGE

1/0 OPERATIONS

?.S

A S"Is t em $ \J b rt out Tn n to f I us h ·a 1l
r e quests f ,. o"' .a de vI e e
•eQuest 'fist fof' ttl\e Task on Whfch 1/0 fs belno rt,Jndown Coer

~COM)

fs cat fed as fol tows~

R0 ~~ · PUC ant~~ addPess (f r~m UIT)~

J ~ R Pc; a , ', f'L, § M

·POWER~rAI~URE

RECOVERY
.... ...
.

. - - ..
········--··-·--------·
•

•

...

Wh~n

•

·•

•

the system ,e~overs

from

fs
. ·Setuo to service the trao,
_ Recovery

System

Trap

gbwer

generated fo'

faTlure,

P~wPP

al I' T'asks that are

,1/0 .Hand I' e I' Tasks a r e c o de d to do what e v e f' I s n e c e s s a r y to
· t e ~ o v e I' ·• . I n s o me c a s e s , t h Ts J s s ·1 mP t y r o p e a t I "' g a r P.i q 1'1 e c: t

Jf ~ reQuest w~s being processed~ vlz,, Hagtaoa
casns, recovery Is
c om p l e t t o n a t o o"' e , f a r I y r e ·,

ethe,

detar~lned

· v Jz•,

'••wPJtfng,

t~e

raaa,

degree

I f p o we r f a I I s d u r J n ':1

write, the Handlaj T~sk must
anything was wrl~ten and pondT~Ional IY
Magtape

~n
~f

determt~e

whe~hpr

bac~spaca

before