Experiences with distributing graphic software between processors Page: 4 of 8
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containing other parameters and COMMON
variables. That is, the array size may
change at run-time, up to a maximum
declared size. In addition, there are
specification commands to specify which
computer each subroutine runs on, which of
each subroutine's parameters are only used
(value never set) and which are only set
(values never used), and whether or not
the subroutine should execute in parallel
with its caller.
Experiment 1 -- Distributing Draw
Two existing graphics applications
were distributed onto various pairs of
computers using the system. The first,
DRAW, is an application program for
producing high quality two dimensional
charts and graphs, lt provides an
intelligent interface so that a user is
not required to write programs but answers
questions and enters the appropriate data.
DRAW is implemented on the CDC computers
at Los Alamos. The CDC-7600 version was
chosen to distribute between a DEC/LSI-]]
and a CDC 7600.
DRAW consists of two parts, the
interact on handler for commands and
editing and the display generator; the
display generator is implemented using
DJSSPLA, The natural split was to move
the interact ion handler to the LSI-ll.
The part iculir distribution of the
interaction handler was accomplished in
five different way- and measurements were
taken for each method.
This is t cit o iginal version of
DRAW in which all of the sof tware
runs on the 1600,
The interaction handler was ,
moved t o t he I.,S -11 and t he
communical ion was d f in d usin the
distl i .o: ietg snf t i . i thin
particular tare, if COMMON bloc Ic
existed, all of the data in (OMMON
blocks was I tianiti t t Ied each way,
II ing Ihin pt oer!s , we dic!viri ' id
malny pluhbrems of tiht use of COMMON
iand its elf l on etfoitir.in' 411
di'it i uted syst em'.. This dicov r
I ld us to :It ud' tit, lint' of COMMON .ai
to ctlicul y tollt tol how much i'-
t r itmi t td etch way. F i'got I shI ow,
the li i l nt d e 11 I mod i ii I 'p ty i a
other figures are averages cf several
program runs at different times and
days on our time-shared VAX and Cray
computers without any special
EXPERIMENT 1: ELAPSED TIME TO MODIFY
(AVERAGED OVER SEVERAL RUNS)
I~t 1.4 If 1.7
1 .2 .1
1 d 3 4
figure Ials5 shows 'W0 S t,S of
line speeds; the in-houe lines ire
300 baud irom ithe terminal to the
hIsi and .1c 1 00 u i roil the h'IC I 1a
the t2r11 in iI, Add I tionaI l iii -iii
i nes art- 120 b Iud each w.IV,
Verrri on 1
The int erIrt ion halnd I 1 w,I:,
dirt ributedl t o the L.SI-I I .I:" in
Version I. tn Ihi:, verr ion, the 1h4,!,
t r I.s;i I t ed :t hi hi ' l I ' l( COMMON I
tit- i 1-1i but the I -l only
t ran!+mi 1 t-d ch,1ges c; I t hI ;IrMMcNs
ack t o 1 he hc,!, . e 14, 1o u u c I'
Vc us r: e in onr I.
(I it bIt ed , ihc" hIo r" I1 11" I l I r
on Iy t h, v.I i :),le t, I n COMMON.. I hat
coot .Ii nt- d, I. , :ICII 1 1I. ; 1 1 U 1u I;I
1' Il o a m.nl~ I,' I l lu t;:Il d In I I ',I I
Th mit' itSutmInl It I h i , ainil ill l
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Hamlin, G. & George, J.E. Experiences with distributing graphic software between processors, article, January 1, 1982; New Mexico. (digital.library.unt.edu/ark:/67531/metadc1061166/m1/4/: accessed December 11, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.