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130-101-035-00

June 1972

6 pages

Original

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Document:	RSX-11D System Overview
Order Number:	130-101-035-00
Revision:	0
Pages:	6
Original Filename:	http://bitsavers.org/pdf/dec/pdp11/rsx11d/RSX11D_Spec_Jun72/130-101-035-00_SysOverview_197206.pdf

OCR Text

RSX'!'!1_1D SPEC

,.
·-·-·---···
..
..

TO i

~SX•llD Di st ,.1 b~t l on

V\D Ovt,

1; ~ '-e wmp;JJ,crvi

f' Rf') M: H·, K r e J c l

o Ar e: 1 !. 6 J 'J

n· 1 2

The ~ate,fal Jnc!udect fn .thls 'u"ctlnna1
spaclflC<.i.tlon, inclucjfng but net ! lmf tej
to.
tnstr~ctto~
times ano
oceratln~
s p e e d s I e; f o r I n r o r !!I a t T o n o u r p " s 9 s c "' I y •
~J ~~.. s u c n ma t a r I a I f s s u t, J e c t
t o
c rvrn -:i P.

notice,

~lthout

Concecuently O~C rn~~~s
oe I l a o I e f o r I t s

c ' a l ;n an d sh a ! I no t

accJ r'ac r·.

INTROWUCT!ON
ls a Real Time OPof'atlng .Syste"" for the PQP•~.l/4t\,
tnat
ls phJ losoonTcl1.l !':I srrnf ·lar tc RSX•jS wrth t:'."'\~ ;?.d:-Ji ti':"n
of: r1xed ~nd/or ayn~mtc o~rtf ttonfng, re•rntrnn~ 1 lbr~rTe$,
output
snool Ing, ChPc~c~l~ttng, and rijn•t!me P~rtlti~n

RS~·11!"!

s e I e c t J o 11 ,
A ~ 3. J c r d i f f ~ r ~ ri c e f ,. o ~ P Sx .. ~. '
1s
t ~ :l
1..; ~ €
of
" t. v. e n t F' j n g s '' I n s t e a. o o f " E. v e ,., t V~ r J a t' I e s " 1 a r a t ~, e a n i r I 1: 'i
to ~~ITFOK a logf cal comolnatl~n of ovonts,

SY5TEM DESCRIPTION
RSX·11D ls an event drfv~n, f(xed/varl2Qle oart1tfon, 1i~k
based,
software Prlorl:v multl-oro~ram~lng syst~~ ~n~t
~r~vldAs f !exihla schedul l~g, program
protect!on, prforJty
aueucd I/G, and fast int~rruot ras~onsn,
Tho syc;ten1

ls des I Qneo for use f n l ndustr I a I proceis cC\ntro I
sto,a~e

of nri~r1~s

an d 1J a ta , c f f I c ! ti n t an d ~ o ri v e n f e n t s c rl o ~ w·1 I n g a f
a n c1 ,, a o I d r e s p o n s & t o I n t e r r ~; ~ t s l s r e o u l r e d ·,

o ~ e r ~ t i o 11 s ,

anrl

taborntory

aop · 1·1catlon~ w~ern

df ~k

P-~..X~ 11.0 SYS 1EM 0 vt: RV I E W

PAGE·

~ha bas i c t' r o g r am

consrsts of
wrftten fn

un Tt u n d a r .RS X-11 D. f s -: a t I A d a ···n Task '' a. n d
program or set nf p~4grams tnat have basn
fORT~AN
and/or
PDP-11
~sse~bl'I
tanou~~~.

-Relocatable

object

. of f ~T l no,

·on .. I rno,

modules

ar e

and

created eltner ori .. 1 t1iA

are

"1n411; ta t ~1 e rl t•

on-Tine procass r~sults

This

::\ n

Jn to

.the TasK o" th9 system disk ln absolute
<rea~~ for e~ecutlon),

R£ x• 1t0
c; y st~ rn
In tha recoraln'1 of

memory

form

jmage

PARTITIOrJS
- '.:' ~ -;... .~

rtTtron:3. are areas of
.- .

real nie""Of''/ that ara us'd

There are tvJO mC\d"S of PartltJori u-:J~ge;

·, Ta.sk execution·,
).''User

contf~uous

Control" whero only one

~as~

the . Partition,
&ll"'\d
<2> nsystern Control"
contl!ols al jocf\tfon of memory
CwftnJ,., tno

·exAcytf on
s I 7. e , a n .;

ona

~ora

Tasks,

tl.~o
YtJn~re

m~y

tne

occut'y
-S'/5tE'rn
~

pqrtl ~Jonl

T"e name,

bas~ · ~d~ress,

o f · e a c Ii
P a rt f t t o n
I s s pe. c I t i e d :.\ t · <: Y c;; t ~ 1l
· Co ., f T g u r
t Jm·~ ,,
a n d c a n ri o t h e c h a h g e d o n .. I I ~ a ·,
T~ s ..., s
are rnstal ~i)d to run In a
cartJcular Par rtfon, rut, upon
spgclffc re~uest, may run · In ~ny Partltfon tliat ls 1-at~e
~ oda
i:i t f llQ....

enougn,

.DISK USAGE:

r t o f t n e e x e c u t r v e c o d e I s a RF and I o r RK ot st<. Dr Tv e r
whfch
provfdes
Stora~e
Al location ~no 8!ocK Transfer
functions fo~ PrJvaleied reQuestors~

n a Ta s ~

f s ou f I t , a d r s k a r e a
t s a I ! c c n t .r.i .j t o
eonta)""
tria Task~s roac lr.-age, C'.nd, ff the Task 1~ decl~red
''CneckPofntable", ~ s~apout ~rea ·rs
a1so
ai locatcj,
The
T as f.
f ni s ~ e
I s w,. i t t P. n s u c n t h a t a s J n ; I e t r ~t n s f e r C' ,1 n n e
usao to loao Its f""'age intci a Partltlon,
Exceo·i: f~r
C:looal
Comnon Rnd Resraent LIDrarY Routines c~hlc~ ~re not ~ nart
.o f the d I s k r ;nag a ) , a Ta s :-< r e q u I r as cont 1 g lJ o 1.4 s r ea I n a .... J r y ~.
~' h a

T r.i a 9 a

MULTIPRO~RAMMING

Effective
r es i d en c y
resfde"CY

multforoura~mln~

Ta s k s •

deoends

and u o o n Ta s K s

uoon

~u!tlp!e

~ o en ~ I " g

s o ;1 ~ :> f

~eMory

th e I r

wafting
for
IIO
compjetfon,
~altlng
fnr
synchrontz~tfo~
w1th oth~r Tas~s, or tn ~o~c w~y oaing
u nab ·1 e t,, cont I nu e exec lJ t I on", Thus, N n I I e ,, n 9 or s ~ v er~ I
Ta~~s

are

orocessor~s

waJtln~,

resources,

anothdP

Tas~

mai

~ti

I iza the centrRI

. R$X~11~

~YSTEM

OVERVIEW

PAGC:

Under RSX•110, Tasks are ryn at~ softw~re pr(nrfty level
tan~fnq . fro~·
a row of one tnro~gh ~ high of 255, and t~e
h(ghest ortorlty T~sk caoa~1e of execution fs granted the
central orncesso~ resources.
beco~es

Wnen a ·rasK

~eady

1s of a hf gher
orT·.>rlty tn~ln tna C•Jrre"'tl'y executfn~ Task,
~he
lo1oJ~r
orToPlty Task ts Interrupted and the h!gnar orlor1ty r~sk IS
a I l '> we 1
t o
r '-Jn ·,
F: x a c ~ t f o n o f
t h e l n t EH I" u n t e ~ T , s I< i.:"j I I
co"tJnua when ft once agafn oecomes the hfghost orlo~lty
Ta 'J "
c r\ p a b I e · o f
o x e c ~ t l o ri ·•
Tn ~ e n v f r o n "1 a n t
o f"' ~~- a n
lntorrupted Task 1~ ornserved, and, exceot t~r elaosqd tfme,
f n t a r r ~"' ;Jt"t o n I s t r a n s P n r e n t t o an I n t e r r u p t e o Ta s k ,
··~ •
TriTs

to exeeute, And

mLJltJorcgrar:imfnq

memory• r es f dent

normal IY

norm~lly
m~ltJprogrammlng fashion even
for the f.'.?XACt;tlon of a hlgMer

t'lnt~

aoof fes

I ·• e ! , one e a Ta s ii< l ~. l n "no rn 'H' y ,
to
ru11
to
corno1otlon
Jn

T 1\ s ks·,
al'lo\"1od

Jf Jts

m~~ory he~o~e~ re1ulr~d
orfority T'lC3t<', Hcn·Jt:J\ler, '>1hen

to
free a PartTtlon for "Xeci;tlcn t)i a
hJt]iier
. orforftY
Task,
a
Task
m~y
he
decl~r~d
'' c h e c k n o f n t a b I € ti w1-1 e n I t I s l n s t a I I e d •
Ch ~ c k p o I n t ~4. b I a T ~ s k s
are swnpoed~out wr.en thofr Partition Is ro~~lr~d for a

dasfrar.je

higher
Priority TasK, and swaooed·I~ wnen t~ey ~nee ai~ln
be cc me the h f- ~:est pr i or l t y Task ,. e Qu r ,. I n g I ts_ P: i r t f t I en r,
No r Ma I I y ,

a Ta s K I s b r o u g n t

for

exec~tlcn,

Tcit o ~om o r y c ri I y u o on a r e Q tJ as t
several
Tasks m~~ use th~ sft~e
""emory..
However,
viW~en
des I rab 1a,
a
T::isk
..,av
be
" f r x e 0. I n - ~em 0 r y ,, ri a ~.Tl I t t I n g f n s t e r r esp 0 n s a t 0 r e c U,q st s T ".'.') r

(ts

execution, but

~nd

aadfcatfn~

a Partftlo~, or

~a~t

of one, t,

~ x ~ c u t ! o ri

s I n.g l e Ta s 1< ,

SIGNIFICANT EVENT~ ANO EVENT FLAG~
A T.a s K i s c o n s f d e r e d n a c t I v e '' f r o m t h e t f :n ~

re"uaste1

untr I

the

tfme

Mas

ft s

EXITed, and tne

maTntaJns a orlorfty orc'3reo lfst of active
Ta~~ List,
The s~stem is 1rfvPn
fo ·11owfn1 ~ay,
A t:;ignJflcant Event Ts a

Active

sy~t~m
ca1tq'1 t~e

Tas~s
~his I lst

conGitlon

that

t~e

that recognf zP.s tn1t a~ event of
slgnff lc~nee nas occurred, Whenrvcr a Sl~nlf lcant Eve~t fs
deel~reJ,
any exAcutfnq Task Is Jnterruptad ~nd the active
T a s k L. f s t T s s c a n n c d f r c ., t. h e t o o A x f\ mI n l ~ q
t ~, J
s t :.\ t •1 ~
" f
Ta~k~
In dec~ndlng Prlnr!ty croor u~tl I a T~sK ~a~a~iA cf
e x e c;i J t I o n
I s f o u n d :,
Ex e c y t I o n o f
t ti o
Ta s ~
Is
t n r:i n
lnltfated, or ccntTnuad, untl I erther1 1) tho T,Sk ~xTts,
declar~d

the

Task

co,,,p'f'etfon),

orfortty Task
occurs

only

progr~m

~ust

w~It

for

another

event

<viz~,

I/0

3) a Stgnjftcant Eva,,t occ!..4rs ·:ln·i a >il':)n"r

cap~ble

resqjt

of
of

execution~

T~s~

_Sl9nf ftcant

switching
Event,

a!"ld

Rsx~110

SYSTEM OVERVIE~

PAGE:

·Sfgnlf Jcant Events ·are dacla~ed when events of sJgnff fcance
occu~, f~e,i RSX~~1D Is ·an event driven s~stem,
wTth Slgnlffcant Events ·are f 1~gs ca1 led Event
Flags,
Qoclaratl~n
of a SlgnJf fcant Event Indicates th~t
so~ethlng has ~aPPenea, nnd
the settln~ of a oartlcular
Event F'la9 lndlcates what has haPcaned~ For exa~pla, · ~pon
coropTetfon of !/O requests, '1aridler T~s:.<s norm? I ly c;et a
r e Quo st or
l n d f cat e d Ev or' t F I a g and de c I a r e a s ! g ~ I f I e. a ~ t
Event. If tha req4e~tf ng Task has (nstr~cte1 tMe sy~t~m
that ft co~IJ not execute untf I the Event varfablP. harl been
Associated

set,
t t\ e

T~sks

Ac t f v e

I ower
l or I ty cou Id .be ru~ oaca•JSP.
scaiis
Task
LT st co u Td pass th a Ta s K w:\ 1·t I "g t., r

coripletton untJ I the Sfgrilf lcant Event
r:esu!'t of tne I/O
.. .comcletlan',

was

oeclarE>d

"Jf

tl 0

· ~~

Each

Event F"lags of w"'l~h
Ta~K, and thlrty~two a~e

Task nas acc.ags to s(xty•four · (64>

(32) are unique to each

thlrti•two
commr>n

to a I r taSKS I

SYSTEM TRAP~
ab( !Tty

to
sorvlce
certarn
eondltfons
without
testfng for their ~xist~nce ls nrcvld~a via
" Sy s t em T r a p s "'•
Th e s e T r a P s c o n s (st o f a I I ,, K a g e .... e t n ~ d t o
optional
f n•Tas~
trao servlco routines~
rn~
scrvl:e
routfnes are fnstal led as a part of thA Task, l lmli:ed ...._Y the
same restrlctro~s as tne Task, and run at tna Ta~~'s
orTorfty as a res~lt of a System Trap conMltlnn~
Thfs
fse1Tlty
al'so Provide~ a means of r~soonalr.q to t"°'e
e x e o t~ t I o n o f p r I v I I e g e d .1 n s t t u c t [ o n s an d no n • Hs X- l 18 E T s ,

The

contrnuousl~

If tho system fs not expllcltly notTffed of the exfste~ce of
a System T,ao service ro~tfne, the System ~raP WI I I not

occuo,

ON•LlNE TASK DEVE~OPHENT
Program development under RSX~11D Ts
provided
sfngle•strAam
Batch capabf I Jty,
P,.ogra:'l1
ynlis

:nay

comol !eri (Fortran lV) .1 . Task lma~ec; may be bul 1t
lnstallad or
removed, and fTle manlPulatjon utility

assembled
and

Of'

OpQratf ons ~ay be

~a~formed~

Rsx~110

T~£

SYSTEM OV~RVIEW

PAGE

MONITOR CONSO~E ROUTlNE

·Opera.tor fnterfaca to thR s~stem Ts or()vlded by
c a 'f I ~ d th e " McR " f Qr MQ n I t or Co n s o I e Rou t I n e ·,

faelTlt~

MCR dlafogue Js establlshad by typfng a tC on a TTY'1
Thfs
·c s e s an MCR d 1s p a t c h Ta s k t o r u n wn l c h o u t o u t s a n '' Mc R·, " ·

symoof and reads a llna of com~ano lnout,
T~o
I nout IT ne f ndl cates what funct I on J s to ~e
·Performed and contains oa~ametars wnen necessary,
The
dispatch Task causes .an MCR r~nctJon T~sk to run, whlch
Pe~forms the reQyested funetTon~
There Js one MCR Functlon
· y~sk for evary MCR funetJon~
·
Pr~mntfng

command

A t:1ploa'I' system mlsnt have MCR functf .o ns to provide system
-,tatv.s.,
oe,form
Task
schedurfng 1 ohange t..ogtcal unJt
AssJgn~entst

etc~

RS~·110

Slnce

normal'

SYSTEM

DIRECTIVES

Tasks are · used to
tmotcrr.ent HCR
~unctions, '
soeclal
ourposa
functTons -to orovfde added
f I ~ x l b f l l t Y o r co riv e ri I e n c a f o r a p a r t I o u ! a r
a o P 11 e at I o n o r
Jn st a I I at l ? u.m.a y be a~ s i I ~ d '1 ve I oped and added ,

·~~stem OTrectfves 6r
s~stem
to perfor~
lm~lemented as EMTfs

Bijbroutfnes,

Dt~actfves

OJ,eetTves are Jnstructfons to t~a
an fndieated oporatlon~ ntrectfvos are
and support~d under FORTRAN by I Jb~ary

al'tow Tasks to schedufe other tasks, measure tl~e

1nte,va1s,

Queue

I/0 rectuasts,

Ways, change logTcal unit
at~e,

l/0

utl l r~y op~ratTons 1

susp~nd

a$Sfgnments,

axecut1on fn

exit,

and

varT011s

•erform

HANDLER~

Wfth the GXceptton of the S~stam Ofsk Orlver<s,, whlcn a~e a
e>art of tne executive, al I I/O Ts suPPo~ted bY "IIO Hanrll'?F
Tasks~,
T~ase Tas~s af ffor from most other
Tasks fn th3t
f1) they contain an lntarruct servrca routf ne, !2) th~Y r~n
With addltfonal orfvTe<io, and (3) that a ,.,a-njng convontl-,n
e x Ts t s ( v l z ·, ,
t h e ~ t ne
? Fl n t e r
Han d Te ,.
Ta s k
ts
n am o d

••1p··

,,,,

Memo'~

by MCR commands,

''
l / 0 Han dre I' Tas k s a re a re
"'t'~··

I 0ad ed

I n t e •.

unI' 0 d0 d

f i 0 m'

· R~X~110

SY$TEM OVERVtEW

PAGE

·11c) FeQuests are Queued fo~ each unTt by Drlorlt~ cusual IY
·~~uesto~
task Prlrirfty), and Handler Tasks Plck ,eauests
fr~m t~e top of ,eauest queues,
Th~s, P'efe,entlal
service
Ts
gfven to high Prlorl•Y ;eQuesto~s,
However, when
ap~roprJate 1 Handler Tasks . acce~t
"attach u"Jt to Taskn
JoQuests and the" de•Queue only ,equests f,om the attached
! as k ·, Th 1s c on t .1n u e s IJ n t I T ·a " d e t a-c h u ,., l t f ~ om Ta s i< "
feauest Js de•Queuod, which causes pequests to be de~Queued
b~ SHIOFTtY (off t~e top~ · once again',
betweeri an J/O Handler Task and the RSX~11D
Ts accompl (she.d by oJ;ectTves and by re~entiant
subroutrnes <viz~. to attach, detach, and de-ouewo)1
and the major effo't in deyelocilng a" RSX-.110 Handler Task
· Ts l n d Tv l n g t h e d e v I c 6 , an d " Qt 1n ~oc omP I e t Tn g ~ n l n t I "'a t e
l nt tH f a~ e · to a ho s t s ~ st am·,
··
·
!h~ lnte~face

- s~stem
s~~tem