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I SERVICE INFORMATION FROM HEWLETT-PACKARD
I
I 1st Quarter 1993
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The Optical Spectrum Analyzer
I
I Richard OgglHewlett-Packard
In reality, prisms are too inefficient. microwave spectrum analyzer. The
To reduce the space required by a result is the ability to measure
prism, a grating is used. The effect of baseband modulation information on
the grating is the same as the prism, the optical signal, but without any in-
except the spreading happens much formation about the wavelength of
faster and the light is now reflected the optical signal.
in the other direction. The variable
slit and photodetector are still used.
OSA Wavelength
Measurements
Introduction The Lightwave Signal Analyzer
Again, the OSA is used to show
The optical spectrum analyzer (or The lightwave signal analyzers intro- power levels as a function of
I
OSA) is a very common piece of test duced several years ago are based on wavelength. (This is just like micro-
i equipment on the lightwave bench. a broad-band photodetector used to wave spectrum analyzers, which
These instruments were first intro- demodulate an optical signal. The show power versus frequency.) Recall
! duced about 10 years ago. HP's basic output of the photodetector is that frequency and wavelength are in-
OSA product is the HP 71450A, which coupled to a preamplifier. This verse relations. The OSA sweeps in-
operates in the 600 to 1700 nm range. amplified signal is then routed to a creasing wavelength, which is de-
Standard hardware options include
(See "Optical Spectrum Analyzer,"page 4)
Option 001, which adds a program-
mable current source and Option 009
for 9 Fm input fiber.
Modulation
The Optical Spectrum Analyzer vs.
the Lightwave Signal Analyzer
What is the difference between an op-
1
I tical spectrum analyzer and a light-
* wave signal analyzer that measures
modulation on optical signals? First,
let's talk about how the OSA works.
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The Optical Spectrum Analyzer
A very simple diagram (see Figure 1)
illustrates the basic concept through
the familiar prism. Light passes
through a prism where it is split,
being distributed according to its
wavelength. Next, a variable-width
f slit is used to select only the
wavelength desired, which is focused
I
on a photodetector. This allows the
OSA to measure optical power levels
versus wavelength. Figure 1. Basic Concept of Optical Spectrum Analyzer
Pub. NO. 5952-3463 0 Hewlett-Packard 1993
WWW.HPARCHIVE.COM
Microwave Measurements
1992-1993 Microwave Test Accessories Catalog
Introduction through convenient computer inter-
face and measurements can be easily
Hewlett-Packard offers a complete reconfigured. Calibration standards
line of microwave measurement traceable through NIST provide the
equipment for testing and charac- lowest measurement uncertainties
terizing components and systems and years of reliable service.
from dc to 110 GHz. A test setup can
be assembled from HI' instruments Vector Voltmeters
and measurement accessories de- This solution provides the most
scribed in this catalog. economical measurement technique
up to 2 GHz for individual frequen-
From a functional standpoint, HI' di- cies, and is used with splitters, test
vides microwave measurements into sets, and couplers.
the following categories:
Equipment Selection
rn Impedance Measurements HI' equipment capability ranges from
w Attenuation Measurements inexpensive test systems assembled
from directional couplers to powerful
rn Power Measurements analyzers that furnish dynamic dis-
rn Noise Figure Measurements plays of error-corrected vector mea-
surements. Equipment selection and Vector Network Analyzers
Spectrum Analysis measuring technique depend on the Because these analyzers obtain both
rn Calibration and Metrology Mea- accuracy, speed, and cost require- phase and amplitude information,
surements ments of the application. Some appli- uncertainties are very small and can
cations require complete characteriza- be determined from physical mea-
tion of microwave components. Vec- surements of the standards used or
Impedance and Attenuation tor measurements are usually made by the use of recommended verifica-
Measurements - Types of in development labs to aid compo- tion kits. This system is the most com-
Analyzers nent design and characterization. The mon type found in metrology applica-
bulk of microwave testing is per- tions.
Scalar Network Analyzers formed in production test, installa-
This measurement technique uses the tion, and maintenance, which is ac- Vector Voltmeters
amplitude-only information available complished with scalar systems. Uncertainties can occur from the
from detectors and directional These systems are easy-to-use, low- meter linearities and mismatches be-
bridges. Analysis is performed using cost, and easy for operators to under- tween various components of the
frequency-swept displays in the stand. measurement system. These can also
bandwidth of interest and results are be estimated by knowing the values
quickly displayed on a graphics Discussion of Uncertainties of the individual components.
screen or transferred to a plotter. Sca-
lar measurements are most common Scalar Network Analyzers Reflectometer Calculator
in production environments. Common uncertainties include detec- The HP Reflectometer Calculator (Lit-
tor and analyzer linearities, which are erature No. 5952-0948) is invaluable
Power Meters usually small; directivity of direc- for estimating the uncertainties in
Power meters use only the amplitude tional couplers and bridges; and mis- most systems. For example, measur-
information available from power match errors between the various ing a 20 dB fixed attenuator that has
sensors through splitters or couplers components of the system. The mag- a SWR of 1.5 with a power sensor that
at individual frequencies. Power sen- nitude of the error is obtained by has a SWR of 1.4 could yield an uncer-
sors work over a wide frequency simple tracking and directivity mea- tainty of about ? 0.3 dB. Similarly,
range and are provided with a refer- surements using the recommended measuring a termination with a return
ence signal from the power meter. .calibration and verification kits. loss of 20 dB on a system with 40 dB
Measurements are more accurate and of directivity could yield an uncer-
slower than scalar analyzers, and are Power Meters tainty of about 0.9 dB. Both calcula-
usually performed in production and Uncertainties arise in this technique tions are very quick on the Reflec-
standard environments. from the directivity of the couplers, tometer Calculator.
linearity of the power meter and sen-
Vector Network Analyzers sor, and mismatch errors between the Copies of the 1992-1993 Microwave
These analyzers provide the most ac- sensors and the devices to be tested. Test Accessories Catalog can be ob-
curate measurements available over a Computer controlled systems aid the tained through your local HP sales/
wide range of discrete frequencies. user with the determination of the er- service office. Order publication
Computational power is provided rors present. number 5091-4269E. 0
2 BENCH BRIEFS 1ST QUARTER 1993
WWW.HPARCHIVE.COM
Hewlett-Packard Announces Service
Parts Bulletin Board Service and
Automated Telefax
Blythe MasonlHewlett-Packard HP Service PartsID Bulletin
Board Service (BBS)
HP Customers can now obtain cur-
rent lists of HP service parts, high- Customers with access to a personal
volume supplies and accessories, and computer and modem can request
documentation for HP personal com- electronic files of any of the lists found
puters, peripherals, and Test and on HP FIRST by calling our new HP
Measurement products in two ways. Service PartsID BBS at 1-800-635-
One way is through HP FIRST and PART (7278). Once you are connected
the other is through HP Service to HP's computer, the dialog will help
PartsIDs Bulletin Board Service you configure your personal com-
(BBS). Both methods are available 24 puter to the right settings. Before you customers to send inquiries to a dedi-
hours a day, seven days a week, and dial you may want to set your PC to cated system operator. Customers re-
both provide accurate, detailed part the following basic settings: ceive answers to their questions in 48
descriptions, pricing information, hours or less.
and recommended stocking levels. Emulation - VTlOO
Connection Options: Update Schedule
HP FIRST - Parity Os17
- ENQ/ACK At the beginning of every month, all
HP FIRST (HP's automated fax re- - XON/XOFF Input Control HP service parts lists are updated to
trieval service) is available by calling reflect price changes, part number ad-
' 1-800-333-1917. A Voice Response
Unit (VRU) directs customers to an
index of all available parts lists. To
request a particular list, customers
enter the appropriate document refer-
ence number and the telephone
This new service will allow customers
to view parts lists on-line, download
any or all of the parts lists in an ASCII
format for use with resident applica-
tions, and interact with an HP service
parts database that can help custom-
ditions or deletions, and recently in-
troduced
should plan to call early each month
to receive the latest HP service parts
information.
products. Customers
number of the destination fax ers quickly locate specific parts. For more information on either
machine - then hang up. Within mi- HP FIRST or HP Service PartsIDs
nutes, the information is transmitted Another feature of the BBS is its elec- BBS, contact Randy Wagner at
to the fax machine selected. tronic mail capability, which allows (916) 785-3257. 0
tract numbers for provisioned prod-
1'1- n * _ P I T ' 1993 ucts, and rcommends replacements
Logistics for discontinued products. The com-
panion microfiche lists NSNs for
Data Book product components and can be re-
quested with postage-paid cards in-
cluded in the data books.
- John Cloutier/Haulett-Packard
If your work requires U.S. Govern- To obtain a free copy of the 1993
ment National Stock Numbers Logistics Data Book, contact your
(NSNs) for HP products and their nearest HP office, or:
components, HP's annual Logistic
Data Book and its companion micro-
fiche are must-have resources. John Cloutier
f Hewlett-Packard Company
The data book cross references HP Federal Support Services
product numbers to National Stock MS 51U-TH
Numbers (NSNs) and Joint Electronic P.O. Box 58059
Type Designators (JETDs), lists con- Santa Clara, CA 95052-8059 0
1ST QUARTER 1993 WWW.HPARCHIVE.COM BENCH BRIEFS 3
(`Optical Spectrum Analyzer," continued from page 1 )
creasing frequency. (Yes, one could
say that "it sweeps backwards," but
we do not use that term.) The range
of the OSA is 600 nm to 1700 nm. As
a comparison, the visible wavelength
range is approximately 300 nm to 650
nm (but varies somewhat from indi-
vidual to individual). It is interesting
to note that in lightwave, longer
wavelength corresponds to higher
performance. So sweeping from short
wavelength to long wavelength is
analogous with pushing to higher and
higher microwave frequencies.
OSA Resolution
But if the OSA is conceptually much
like a conventional spectrum
analyzer, why is it not used to see
modulation? It could be, depending on
the relative bandwidths involved.
The OSA has "resolutions" (like resol-
Figure 2. Fabry-Perot Laser Test Measurements
ution bandwidths) from 0.08 nm to
10 nm. A common wavelength for op-
tical work is 1300 nm, which is about
230 THz. At this wavelength, a resol-
ution of 0.1 nm is about 18 GHz. So,
modulation can be easily seen if its
bandwidth is considerably wider than
18 GHz. Optical modulators that have
a bandwidth this wide are not yet
commonly found. Most RF modula-
tion of a laser is only a few GHz in
bandwidth, so all the modulation in-
formation falls within the resolution
of the OSA. It is like trying to look at
1kHz sidebands in a 1MHz resolution
bandwidth. Therefore, the OSA does
not replace the LSA; you need both.
OSA Measurements
So what measurements are made with
an OSA? Certainly it can be used to
see at what wavelength(s) an optical
device is emitting. It also shows what
the relative power levels or power
widths are. This is valuable for white
light sources or infrared LEDs. The
OSA can show the bandwidth if the Figure 3. DFB Laser Test Measurements
device is broadband, or show what
wavelengths are present. the spectrum the FP is covering, or stead of coax for numerous reasons.
how well unwanted modes have been Optical fiber requires the ability to
Two very common lasers are the suppressed in a DFB, mode spacing, amplify optical signals. Researchers
Fabry-Perot (FP - see Figure 2), and and so forth. Advanced measurement have now developed Erbium-doped
the Distributed Feedback (DFB - see routines make these and other mea- amplifiers that amplify light; optical
Figure 3). The FP laser has multiple surements on these lasers at a single in, optical out, without going to elec-
modes and looks something like a touch of a button. trical signals. The OSA is useful for
pulsed-RF signal. The DFB laser sup- looking at this gain and noise, as well
presses all but one of these modes. The Cable TV (CATV) market is mov- as bandwidth. My next article will
The OSA can measure the width of ing toward the use of optical fiber in- cover these subjects in more detail. 0
4 BENCH BRIEFS WWW.HPARCHIVE.COM 1ST QUARTERS 1993
HP LaserJet Printer Service Tip mirror coating (silver or other reflec-
Don't Touch tive metal) is applied to the front sur-
face (rather than the back surface) of
Those Mirrors the glass. Cleaning these mirrors
could very well result in the removal
If you experience a 51 SERVICE error or scratching of the metallic material,
on your HP LaserJet printer, do not thus destroying (or at least com-
attempt to clean the beam detect mir- promising) the mirrors' ability to
ror to resolve the problem. properly reflect the laser beam. If the
beam detect mirror is damaged, the
Please note that all mirror surfaces entire printer will have to be replaced
now used in HP LaserJet printers are since the beam detect mirror is not a
"first-surface'' mirrors, meaning the field-replaceable part. 0
GHz. This 1-metercable is flexible and this cable include long life in the ser-
Do You Need ruggedized, and is appropriate for vice environment, especially at the
a Precision use in bench and system testing
where repeatability and low-loss
connector-cable interface, where
these types of cables traditionally
Microwave Cable? aboye 18 G H is required.
~ show their weaknesses.
Hewlett-Packard has a precision The cable assembly is manufactured To obtain the price and order this
microwave coaxial cable assembly by Huber Suhner AG, a leading man- cable assembly, contact your local HP
with 3.5 mm (male) connectors for ufacturer of coaxial cable assemblies saleshervice office and order HI' Part
testing sources and analyzers to 26.5 worldwide. The reasons for choosing No. 8120-4921. 0
1993 Bench Briefs' Instrument Service Note Index
HP FIRST (208)344-4809
T&M Section - Press 4
Password Section - Press 3
Password - 76683
SN SN Abstract HP FIRST
"me No. Document ID No.
IO 3324A-02Instructions on installing Phase Calib Opt 003 or Opt 004 5624
IO 3325A-24Power transformer replacement instructions for std/opt 002 5652
MA 3582A-18 Mod prevents A1K6 input relay contact damage 5665
MR 4195A-15 Firmware rev 2.1 fmes incorrect plot-out results 5651
MR 4263A-01 Modification cures open correction failure 5523
MR 4263A-02Mod prevents potential short circuit from blowing A2F1 fuse 5657
MR 4263A-03Replacement X'tal oscillators prevent CPU hang ups 5658
IO 4274A-32ARepair method for A9 MPU brd w/special freq ROM 5567
IO 4275A-28A Repair method for A9 MPU brd whpecial freq ROM 5568
MR 4338A-01 Mod prevents potential short circuit from blowing A2F1 fuse 5659
MR 4338A-02 Replacement X'tal oscillators prevent CPU hang ups 5660
MR 4339A-02Mod prevents potential short circuit from blowing A2F1 fuse 5661
MR 4339A-03Replacement X'tal oscillators prevent CPU hang ups 5662
MR 4349A-02Replacement X'tal oscillators prevent CPU hang ups 5663
IO 4396A-01Part numbers of F/W installation kits and related material 5642
MR 4396A-02F/W upgrade corrects auto zoom and savehecall operations 5643
IO 498OA-10 Instructions on repairing the color LCD display 5513
1ST QUARTER 1993 BENCH BRIEFS 5
WWW.HPARCHIVE.COM
SN SN Abstract HP FIRST
Type No. Document ID No.
f
7
IO 498lA-10 Instructions on repairing the color LCD display 5514
IO 4982A-10 Instructionson repairing the color LCD display 5515
MR 4995A-01 Modification eliminates possible power up problems 5632
MR 4996A-01 Modification eliminates possible power up problems 5633
IO 506lA-22 Specificationsfor replacement cesium beam tube 5686
IO 5335A-17A Suggested replacements for front end Schmitt amplifiers 5597
SA 5342A-58C-S New cabinet support strut and top cover 5635
SA 5343A-31C-SNew cabinet support strut and top cover 5636
SA 5344A-OlA-SNew cabinet support strut and top cover 5637
MR 5345A-43 New part corrects power-up display problems 5655
IO 6050A-01A Recommended procedure for fan speed adjustment 5683
IO 605lA-OlA Recommended procedure for fan speed adjustment 5684
IO 6264B-05Information on recommended replacement main power transformer 5528
IO 6267B-05 Information on recommended replacement main power transformer 5529
IO 6274B-05Information on recommended replacement main power transformer 5530
MR 6575A-01Mod improves reliability of sense protection resistors 5507
MR 6625A-02 Rec replacement of fuses improves performance 5508
MR 6626A-02 Rec replacement of fuses improves performance 5509
MR 6628A-02 Rec replacement of fuses improves performance 5510
MR 6629A-02 Rec replacement of fuses improves performance 5511
MR 6675A-02 Mod improves reliability of sense protection resistors 5512
MA 8112A-04A Rec repl of timing ICs require modifications 5503
MA 81l5A-01 Rec repl of timing ICs require modifications 5504
MA
MA
8116A-06A Rec repl of timing ICs require modifications
8118A-01Rec repl of timing ICs require modifications
5505
5506
t
MA 8340A-22 Rear panel to front panel retrofit instructions 5628
MA 8340B-05 Rear panel to front panel retrofit instructions 5629
MA 834lA-11Rear panel to front panel retrofit instructions 5630
MA 8341B-04Rear panel to front panel retrofit instructions 5631
IO 8560A-12 Corrections to IncrementalLog Fidelity tests 5666
MR 8560A-14 Mod pnmts possible damage to video out buffer on A2 interface 5572
MA 856OA-15 Performance enhancement to eliminate graticule "hooks" 5573
MR 856OA-24 Rec mod improves performance in offset loop divider IC 5574
MR 8560A-25 Rec mod eliminates tracking generator feedthrough performance 5575
"7 MR 856OA-26 Rec replacement of defective 5-Volt regulators 5609
MR 8560E-02 Rec replacement of defective5-Volt regulators 5610
MR 856lA-25 Mod prevents early failure of A12 solid state RF switch 5576
IO 856lA-26 Correctionsto IncrementalLog Fidelity tests 5667
MR 856lA-27 Mod prvnts possible damage to video out buffer on A2 interface 5577
MA 856lA-31Performance enhancement to eliminate graticule "hooks" 5578
MR 8561B-12 Mod prevents early failure of A12 solid state RF switch 5579
IO 8561B-15 Corrections to IncrementalLog Fidelity tests 5668
MR 8561B-16 Mod prvnts possible damage to video out buffer on A2 interface 5580
MA 8561B-17 Performance enhancement to eliminate graticule "hooks" 5581
MR 8561B-24 Rec mod improves performance in offset loop divider IC 5582
MR 8561B-25 Rec replacement of defective5-Volt regulators 5611
MR 8561E-01Rec replacement of defective 5-Volt regulators 5612
IO
IO
8562A-55 Suggested replacement for YTF in Option TO1 products
8562A-57 Correctionsto IncrementalLog Fidelity tests
5583
5669
c
MR 8562A-58Mod prvnts possible damage to video out buffer on A2 interface 5584
MA 8562A-62Performance enhancement to eliminate graticule "hooks" 5585
IO 8562A-65 Correct part number for A9 Input Attenuator 5586
6 BENCH BRIEFS 1ST QUARTER 1993
WWW.HPARCHIVE.COM
SN SN Abstract HP FIRST
Type No. Document ID No.
MR 8562A-66 Rec mod improves performance in offset loop divider IC 5587
MR 8562A-67Rec replacement of defective 5-Volt regulators 5613
IO 8562B-55 Corrections to Incremental Log Fidelity tests 5670
MR 8562B-56 Mod prvnts possible damage to video out buffer on A2 interface 5588
MA 8562B-60 Performance enhancement to eliminate graticule "hooks" 5589
IO 8562B-63Correct part number for A9 Input Attenuator 5590
MR 8562B-64 Rec mod improves performance in offset loop divider IC 5591
IO 8563A-08 Corrections to Incremental Log Fidelity tests 5671
MA 8563A-11Performance enhancement to eliminate graticule "hooks" 5592
MR 8563A-19A Rec mod improves performance in offset loop divider IC 5653
MR 8563A-20 Rec replacement of defective 5-Volt regulators 5614
MR 8563E-0lA Mod eliminates intermittent sampler unlock errors 5654
MR 8563E-02 Rec replacement of defective 5-Volt regulators 5615
IO 8566A-26 Repair and replacement of M A 2 rotary pulse generator 5616
IO 8566B-05Repair and replacement of M A 2 rotary pulse generator 5617
- MR 8566B-39Mod corrects intermittent PC edge connectors on A4A4 BW assy 5672
MR 8568B-33Mod corrects intermittent PC edge connectors on A4A4 BW assy 5673
MR 8657D-02 Modification corrects reversed capacitor on A6 Output Assembly 5638
MR 86575-01Modification corrects reversed capacitor on A6 Output Assembly 5639
IO 871lA-01 Incorrect part source listed in service manual 5641
7 IO 875lA-09C Information on relationship between firmware rev and ROM set 5524
MR 875lA-14 Mod prevents hang ups when being controlled by a controller 5604
IO 875lA-15 Internal Test 21 might fail due to severe test limit 5605
MR 875lA-18 New F/W improves perf & corrects probs described in Table 1 5606
IO 8981B-0lA Firmware history and upgrade procedures 5519
MR E140lA-01 Mod prevents random system resets 5687
MR E1426A-01 F/W upgrades improves performance and corrects known problems 5601
7MR E1650A-04 Connector modification fmes ECLTRGl output 5621
MR E1652A-03 Connector modification fmes ECLTRGl output 5622
MR E1655A-01 Connector modification fmes ECLTRGl output 5623
IO E2500A-10 Rec replacement of interconnect cable during service 5520
IO E2500B-06 Rec replacement of interconnect cable during service 5521
IO E2500B-07 Use of WGLSEND command to retrieve H W fault indications 5522
IO J2213A-01 Instructions on repairing the color LCD display 5516
IO J2219A-01 Instructions on repairing the color LCD display 5517
MR 16380C-01Mod prevents potential damage to the carrying case 5664
MR 344ClA-02Modification resizes input terminals to accept European plugs 5634
IO 53310A-03 Firmware status and upgrade information 5518
IO 546OOA-08 Key down pwr up seq may clear numerous types of inst lockups 5625
MA 54600A-09Lubrication leaking from behind control knobs 5602
IO 546OlA-08 Key down pwr up seq may clear numerous types of inst lockups 5626
MA 546OlA-09 Lubrication leaking from behind control knobs 5603
IO 54602A-01Key down pwr up seq may clear numerous types of inst lockups 5627
MR 66O0OA-01 ROM rev A.00.03 eliminates improper unit reset 5685
MR 661OlA-01Mod prevents output connector cover assys from cracking 5644
MR 66102A-01Mod prevents output connector cover assys from cracking 5645
MR 66103A-01Mod prevents output connector cover assys from cracking 5646
MR 66104A-01Mod prevents output connector cover assys from cracking 5647
MR 66104A-02Mod prevents output oscillation in 2 to 3 kHz range 5648
MR 66105A-01Mod prevents output connector cover assys from cracking 5649
MR 66106A-01Mod prevents output connector cover assys from cracking 5650
1ST QUARTER 1993 BENCH BRIEFS 7
WWW.HPARCHIVE.COM
SN SN Abstract HP FIRST
Type No. Document ID No.
I
v
MR 70205A-OM Recommended ROM replacement kit 5674
MR 70206A-04A Recommended ROM replacement kit 5675
IO 70300A-07B Suggested replacements for obsolete attenuators 5676
IO 70600A-02B Suggested replacements for obsolete attenuators 5677
IO 7060M-02B Suggested replacements for obsolete attenuators 5678
MR 70620B-01Mod eliminates residual responses caused by noisy pwr supply 5595
MR 7062lA-01 Mod eliminates residual responses caused by noisy pwr supply 55%
IO 70900A-14K List of firmware compatibility 5618
IO 70900B-01FList of firmware compatibility 5619
IO 70904A-05B Suggested replacements for obsolete attenuators 5679
IO 70905A-05B Suggested replacements for obsolete attenuators 5680
IO 70906A-05B Suggested replacements for obsolete attenuators 5681
IO 70907A-03B Suggested replacements for obsolete attenuators 5682
MR 70908A-21Modification to module verification software 5620
MA 8373W32A-01Procedure for firmware upgrade to version 8.94 5640
MR 86790B-02 Firmware history and upgrade procedures 5656
MR 8751OA-01 Mod eliminated "Address Error" at boot up 5569
MR 87510A-02Mod eliminates incorrect Q value in the bandwidth search 5570
MR 87510A-03Mod improves performance around OUTPRESO? and EQUCPARS? 5571
MR 8751OA-04 Mod elimins incorrect results of "OUTPLIMF?" and "OUTPLIML?" 5607
MR 8751OA-06 New F/W improves perf & corrects probs described i Table 1
n 5608
IO 87512A/B-01Repair strategy of enhanced (2 GHz) 87512NB 5525
Service Note Types c
IO Information Only MA Modification Available
MR Modification Recommended SA Safety
PS Priority Safety SM Interoffice Service Memo (IOSM)
. I . 1 ~
For address corrections,please mark up and return
the mailing label below. Bulk Rate
100 Mayfield Avenue U.S.Postage
ountatn View, California 94043
San Jose, CA
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Service information fro
Hewlett-PackardCompa
tain a qualification form for a f
subscription, send your request to
above address.
butions are welcomed.
se send them to the
r
Editor at the above addre
ditor: Jlm Bechtold
Hewlett-Packard
All rights reserved Permission to reprint Bench Briefs granted upon written request to the Editor Printed in U S A .
BENCH BRIEFS 1ST QUARTER 1993
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