Instrumentation
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Unimetrics
Unimetrics Universal Corporation 1853 Raymond Avenue Anaheim, California 92801 (714] 879-3777
Circle No. 106 on Readers' Service Card
60 A .
Stat us of Real. 7XA at 11:51:20 on 20-Fc>b-70 Uptime 17:17:20, 93%. Ν ull Time Job 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Who 30,50
**, ** 11,30
**, ** ** # * 15,35 50, 101 14,34
** ** 52, 102 5,11 13,33 22,42
Where
What
Size
State
Run time
DET ΤΤΥ0 DET TTY15 DET DET TTY12 TTY14 TTY3 CTY TTY1 TTY6 TTY5 TTY11
GCDIR PIP TRADAT INDEX DSKILL MSDAT REMAS TECO TECO SYSTAT PIP PIP GCAN PARAM
2K 4K 3K 5K IK 8K 6K 2K 2K IK 4K 4K 13K IK
SL
00 00 27 00 02 15 00 00 01 00 00 23 00 00 14 00 00 35 00 07 50 00 04 52 00 00 19 00 00 00 00 02 25 00 00 17 00 00 37 00 00 01
tc SL TT 10 SL
tc TT
tc RN TT
tc TT TT
Figure 2. "System snapshot" illustrating the variety of simultaneously active time sharing jobs: GCDIR (job 1) is the data acquisition program for "slow" on-line instru ments; TRADAT (job 3) transfers data from the fast ADC to the disk (used for pulsed nmr); MSDAT (job 6) transfers reduced mass spectra to the disk; GCAN (job 13) and REMAS (job 7) are analysis programs for gas chromatography and mass spectrometry; INDEX (job 4) is a refined analysis program for gc; PARAM (job 14) a parameter-spec ification program for runs of slow instruments
t h e active d a t a transfer), but only valuable spectra are transferred to the disk by the d a t a acquisition and reduction program (MSDAT). During the remaining 3 sec, another mass spectrometer or fast instru ment m a y be started. The G C / M S combination is not yet running in a routine fashion, because some work on the analysis methods, especially for the intensity corrections of mass peaks with the total ion current, has still t o be done. Present System Performance
As the data acquisition is inde pendent of the spectroscopic method, any instrument m a y be connected to the system, which de livers voltage signals between —10 and + 1 0 V and runs either with d a t a rates of 20 Hz and less or with rates between 1.25 and 20 k H z . Up to now, one fast-scan, low-reso lution mass spectrometer and one pulsed-nmr instrument are con nected to the "fast" A D C , whereas 10 gas chromatographs (the elec tronic cleanup of the other gas chro matographs is not yet accom plished), 1-nmr, 1-ir spectrometer, and 1 spectropolarimeter are on-line via the slow A D C . The reliability of the system is improving after some difficulties in the beginning (mostly hardware
ANALYTICAL CHEMISTRY, VOL. 42, NO. 9, AUGUST 1970
failures of the special real-time de vices and a few, but nevertheless, disturbing monitor malfunctions). As an average the system has one hardware breakdown every three weeks and about three software "crashes" every week. As shown by the null time in the system snapshot (Figure 2 ) , the central processor is far from being used to its full capacity. But nevertheless there are two bottle necks in the present system causing difficulties under heavy system load: (1) As the installation is not only used for the real-time applications, the present core memory is too small for the number of simultane ous users. The time-sharing moni tor including the real-time code re sides in 16K of core. T o allow up to 32 simultaneously running slow on-line instruments, the associated d a t a job needs 3K of core perma nently. Temporary restriction to 20 simultaneously active lines saves IK. But the remaining 14K of core is not sufficient for 15 concurrent jobs (even, if larger computational programs are run during the nights with a very small monitor), because too much processor time is wasted by swapping actions, and time-shar ing response is decreased consider ably, especially for programs with many i n p u t / o u t p u t actions {e.g.,
