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130-101-039-00

June 1972

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Document:	RSX-11D Memory Management
Order Number:	130-101-039-00
Revision:	0
Pages:	3
Original Filename:	http://bitsavers.org/pdf/dec/pdp11/rsx11d/RSX11D_Spec_Jun72/130-101-039-00_MemMgmt_197206.pdf

OCR Text

SPEC
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f ~ 0 Mf H·, K r e J c f
DA1'EI 17 Jun 72

SUBJf MEMORY MANA~MENT

·ooc1

130~101~039~00

The mater ta I Jnefudod Tn this functional
speoffTentTon, l"cTudfn~ but not llmfted
to, fnstr~ctJon times and
ooePating
speeds ls fer lnfoim~tfon ourposes only,
All. s~ch matarlal Ts subject to cn~nga
wlthoyt notfce! Concecuently DEC ma~es
r\Q cJalm a"d shal I not tle rlablo for
1u; u r a e ~ ·•
·, "~·

(ts

otnerwf se, the terms
''RS X" an d " RS X~ 11 " l mp f y " RSX 91! 11 D '' ·,

Unless spec I fled

Undet RSX•11D, memory f s dfvToad Tnto (1) an
executfve~s

code,

~2>

TI s t s , an d s lJ o r o lJ t Tn e s 1
IJ t·T I l t y L f b r a r -y 1
C5 )
Bl~cks,

and (7) Task

area for t~e
for
the systen's tib:·es,
( 3 ) a n I I O ri1 an d I e r
l I b ra r y 1
c4 )
a
a 6 li f f e r Po o I 1
C6 > G I o ta I ~ o .,, :i' o n
area

Partitions~

These

~e~o'Y

a I ·I o e a t i o n s a r e f l xe d a t S y s t e rn Co n f l g '.Jr a t I o 11

Th e I I O Ha ,., d ra rr L I b r a r y

dlvlsfo~s

anc

( S GE ~: ) ·,

' o P'
sh ar I ng
~ o 11 e
tre~entrant) tnat rs 001111'101"1 to more tnan one ( largn/ d::l:idj~r
Task, and ls used orTmart ly for fj le st,ucturll
code.
P·e
Hand'ler
i.fbrar~
Ts accessaole only by P,lvlle0ao Tasl'(c;,
ThTs 1 f brary may not be recurred
ln al I syste~s, and rs
a

•He c h an I !-i m

optlonallt createo at System Configu,atlon,

!he

UtlTlt~

(re~sntrant

~lbrary

rnechanfs,.,

& oosltJon•lndePende~t>

frir

tn~t

tnan one rnsx,

sharing
ric~0cn

eerie

to ~ore

It Is avai !able to all TasksClJ an~ is
us~c
orlm~r f IY
for
the FORTRAN O~Ject Tl~e Sys ta~ COTS>,
Tlii s
'I I b r & r Y rn a y no t b e· r e q y I ~ e d i n a I I sys t o ;n s ,
a r\ 1
is

optf{lnatlY creatac at s~stem Conf fgura'tfon,

PACE

MEMORY MANAGHENT

The 8uffer P6ol rs an ~rea cf memory to be al l~ca:ed to
PrTvr1eged Tasks fo~ theJr Jnternal usaQe, T~e prf~ary u~a
of the Byffer Pool ls by Handler Tasks that orovldc a ff la
structur-e.
A Buffer Pool may not be ,eQuf red Jn ar I
systems,
and
Is
opt(onal IY
a1·1~cated
.at
S~stem

Conf JguratJon,
Gl~b~l

C6mmon Bj~cks are COMMON areas t~at a,e lntenderl
Tnter•Task communlc~tfon a~d extra•TasK data storqgs.

many GI oba I Co""rnon BT-ocks,
Syst~m

Conf fguratl6n~

I ;ic I Ud l ng none 1

ma~

f~r

be def I ne d n t

areas ·of memory dAdlcated for t~e
exeCk!tfon
of
Tas.ks',
A Partltfon
~ame
ts soeeffl~c, .,.r
Tmrilled 1 whanevar a Task Image Ts . Toadad from ~fs•<' Tnto
memory,
At least one Task Partltlcn ~ust be daf jred,
ra~h
Task Partft(ons, are

Ta s.k Pa. r t ( t f on

'' Us e r
c· o n t r o I I e d
P a r t t t f o n '' ,

a s ':Is t em ·J s I d E' n t I f I e d as be I "'g
Pa r t I 't I o n''
o I'
a " sy s t ~ rr.

e I t ""· s,.

co n t r o I' I ~ d

A·usnr Con'tro I! ed Pa,tJtf on can accommodate onl'I ore T'lSk ~t
tlme, regardle3s cf Its stza; If al I T~sk Partitions are
User · Control led
PartJtlons, then
al I
tiynamtc
~amory
a I ·1o eat I on I s u n d a r the cont v o ! of the u n er-, t ~ J

•

>--)iii:--

A Systnm ,C ontro1Ted PartftJon wi rt acCC'!Tl'T"Orfate as Many
ia1k
as ean flt fn the PartttTon (t:ffrs.,. f f t " algcrith~~'• !f

tnAre fs

o~IY

one

Tas~

P~rtltton

Jn a

sy~tem,

~rd

contro I !'Gd
Partltlon, then al I oynaml c
. a I ·1 o cat f o n l s 1J nd e r t n e c on t ~ o I o f th a sys t e "' ,
SystAm

M9"1'\Qry

With eftha' tyoa partition, a checkpof nt~ble Task wt I I ~e
r
o u t i 1 s p a c a w I t h r n I t s o R r t I t I c n i ~ r e ntJ t r e ~ f o r a
priority Tas~~ A checKnoln~ed TasK (s reto~ced wn~n
suff Jofent space wTthln its PartltJon ls aval I able a~d nit
'e~utrad for hlgher orforlty T~sks,
A cneckoofnte~ Ta5K ls
a1ways brougit oack Into tna same Partltfon Jt ~<=is lnltl~llY
To a· d e d , b u t n o t n e c e s s J a r I I ':t a t
t h e s a ~ e r o c a t l c ,, ~" I t n l n
~ Tt t a n
h1nh~r

that · partf t(on·,

.
.
. .
...................
·•

•

••

C1 ) P r f v T I e g e d Ta s k s e. " a n o t
ma p oe c1
Int o t he
lJ t. IT r t y
l.lbrarY 1 hut bec~usa thAy c~n set A~Rs, a Prfvf le~ed Ta~K
oa n r.i a o l t s a I f I n ~ o t n a 'J t I i l t y L i b r a r ~ 1
. . .
. .
..................
...
".
.

c·2J The EXECUTE, f?X, nnd UNflX Dfrectfves a~e
useful . In tnls case ·,

Partrcu!arl~

MEMORY.MANAGMENT

With efther t~oe partltl~n, a non-ch~ckool~t~ble Ta~k wl I I
F ,em a rn
r- 0 s I dent th ru c 0 Mp 'f et r0 n. . ( u"' t J I I t ' s s u P. s an ~ x! T
Dlreetlve), even If fts mani1o~'i
ls -.- reautrod for a 'ilah~r
orTorft)' Task,
S';stem control led memory al 1ocatTon and
checkpof,,tJnri
are
P o we r f Y I
f a a t u re s •
o lJ t
t he I r use
,. o o ~
t n c r c a '."i e s y CJ t ~ ~.,
ovar~aad ano C3n cause a S(gnlf lcant Increase
In the tl~e
r o Q u f r e d to
corn p ·1et a a Ta s Kt s ex o cut I on ( due to ax c es s j..v a
. ct\ e c -" po I n t J n n

»,

The number and
e fleck o o I n t Jn g,
apol1o~tlon

type

~ask

PartftTons,

and

tne

use

Ts d a Pendent u non the t".' red f ct ab I 1 I t y ·of
and the J~dgment of the oefson Jn charge~

~f
~n