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This is only a preview of the December 1996 issue of Silicon Chip. You can view 28 of the 104 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "Build A Sound Level Meter":
Items relevant to "Build An 8-Channel Stereo Mixer; Pt.2":
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COMPUTERS
CD Record
The major components of the
COMPRO CD-R kit include: (1) a
CD-R drive, (2) a SCSI interface
card, and (3) Gear pre-mastering
software on a CD-ROM. The kit
also includes two blank CD-ROMs
and a SCSI driver installation disc
for Windows 3.1.
Creating your own CD ROMs is fast and easy
with the latest generation CD recorders. And
the cost is coming down all the time.
Although CD ROM drives have been
the norm in PCs for some years now,
CD recorders have been much more
esoteric devices with price tags to
match. Until now that is – in the last
12 months, CD recorder prices have
plummeted dramatically, placing
them in reach of just about anybody.
For little more than a grand, you
can now choose from a range of CD
recorder kits that you can install
8 Silicon
ilicon C
Chip
hip
yourself or have installed for you.
Alternatively, you can now specify a
CD recorder as one of the options if
you’re buying a new PC.
If you need a reliable method of
archiving and storing (or transferring)
large amounts of data, a CD ROM is
well worth consideration. A CD-ROM
can store up to 650Mb of information
and this can either be added in one
session or, provided the system is ca-
pable of it, in multiple sessions.
But while data archiving is the
biggest application for a CD recorder
(CD-R), there are other applications.
CD-R lets you create your own audio
and video CD titles, for example. Some
systems even have the capability of
copying tracks from an existing audio
CD onto your PC’s hard disc so that
they can then be recorded onto a CDROM. Not all CD-R drives support
By GREG SWAIN
ders:
The next add-on
for your PC
copying audio tracks however, so
check carefully when buying a CD
recorder kit if this particular feature
is important to you.
CD-R drives
A CD-R drive looks exactly the same
as a conventional (read only) CD-ROM
drive and can simply be substituted
for the existing unit. CD-R drives are
invariably SCSI devices (Small Computer Systems Interface) and so a SCSI
interface card is required.
A CD-ROM is not like a floppy or
hard disc drive, so it’s not just simply
a matter of copying files to it. Instead,
you have to use special pre-mastering
software and this is normally supplied
with the kit.
The pre-mastering software is
necessary because CD-ROMs use a
different file format to DOS-formatted
discs – typically the ISO 9660 standard. In practice, the pre-mastering
software is used to create a “virtual
image” file of the CD. A virtual image
file lists all the file names and directories to be copied and contains other
information necessary for writing to
Because it is a SCSI device, the CD-R drive requires a SCSI interface card. This
card is plugged into a spare ISA slot on the motherboard.
a CD-ROM. It does not include the
actual data files, however.
It’s also possible to create what is
known as a “physical image” file on
the hard disc. This is an exact copy
of all the information as it is to be
The CD-R drive is slit into a vacant drive bay from the front
of the computer. We disabled our existing CD-ROM drive to
obtain a spare power connector.
recorded onto the CD-ROM and is
created after the virtual image has
been created.
A physical image file is usually only
necessary if you have a slow hard
disc. That’s because CD recording is a
The free end of the ribbon cable from the SCSI interface card
is plugged into the back of the CD-R drive, along with the
power connector. No audio cable is supplied with the kit.
D
December
ecember 1996 9
Creating A CD-ROM: The Basic Steps Using
1
Fig.2: type in the image filename
in the space provided, then click
the Create button. The image
file is created and the program
returns you to the workbench.
Note that only capital letters, the
numbers 0-9 and the underscore
character (_) are valid characters
for ISO filenames.
2
3
continuous process and there must be
no serious interruptions while record
ing is taking place.
If there is an interruption (eg, because the hard disc can’t keep up and
the data buffer empties), the recording
process will be aborted and the CDROM will be ruined. You can then
either toss it in the garbage or use it
as a drinks coaster.
Because a physical image takes less
10 Silicon Chip
Fig.1: select the CD type
to be created at the Gear
workbench, the click the
Create Image button.
time to read than a virtual image, it
reduces the likelihood of the buffer
running out of data during the recording process. The downside is that you
need lots of space on your hard disc,
since all the files to be written to the
CD are duplicated.
The good news it that a virtual image
file is all that’s required in most cases,
particularly if you have a computer
with a fast hard disc. It pays to de-
Fig.3: click the Edit
Image button to bring
up the Data Editor.
fragment the disc on a regular basis
though, to eliminate any possible
problems.
CD-Recorder Kit
Typical of the equipment now
available in this field is the Compro
CD-Recorder Kit. It comes with an
internal SCSI CD-R drive, a fast SCSI-2
interface card, Gear pre-mastering software (supplied on CD-ROM), a SCSI
g The Gear Pre-Mastering Software
4
Fig.4 (above): edit the virtual
image using the Data editor.
Just select the source drive
and drag the files you want to
the My ISO Track window.
5
Fig.5: click the test button on the
workbench to begin a test write.
Alternatively, you can bypass the
test procedure and write straight to
the disc.
6
driver installation disc (for Windows
3.11 users) and a SCSI interface cable.
Thrown in for good measure are a
couple of blank CD ROMs, plus a user
manual and an installation guide for
the SCSI card.
Our first impressions of this kit were
very favourable, as only good quality
components have been included. The
CD-R drive is a Matsushita CW-7501
Plug and Play unit, while the SCSI card
Fig.6: click Yes to automatically
write the image to the disc if the
test is successful or No for a test
write only.
is an Adaptec AHA-1520B. The SCSI
card features automatic termination
which means that you don’t have to
worry about removing terminat
ing
resistors if a device is plugged into the
external connector.
The CD-R is capable of reading a CDROM at quad-speed (4x) and writing at
double speed (2x). The pre-mastering
software also lets you write at single
speed if you have a computer with a
slow hard disc drive.
Unlike some CD recording kits,
this particular setup supports a wide
range of recording formats. It’s lets you
create multi-session and mixed-mode
discs and it supports CD-ROM Modes
1 & 2 (ISO), CD-ROM XA (extended
architecture), CD-I, CD Enhanced (also
known as CD Plus), and CD digital
audio (Red Book audio).
A multi-session disc is one on which
December 1996 11
Fig.7: a physical image can be created if you have a slow hard disc or for maximum
reliability. It requires a lot more hard disc space than a virtual image however, since
it makes a complete copy of the files to be written to the CD-R.
Fig.8: the “show log” option lists the steps that have been taken in creating a CDROM. This can be handy if you get interrupted during the process.
data has been added during several
different sessions. This is useful for
archiving data or updating a catalog on
a regular basis, for example. When the
disc is read back, the CD-ROM reader
automatically presents all linked sessions as one. You are not aware of the
number of sessions on the disc.
With a multi-session disc, you
can keep on adding data until the
disc is full. Note, however, that each
session introduces a data overhead
of about 15Mb. This data overhead
consists of track lead in and lead out
information.
You can also effectively delete and
update files on a multi-session disc.
This is done by adding (appending)
a new session. During this process,
the software reads back the last session and creates a virtual image of it.
You then edit (update, delete or add)
the file contents of this virtual image
before writing the new image to disc.
Of course, data is not really deleted
from a CD-ROM – it’s just that there’s
no longer any reference to it in the
new table of contents that’s created
12 Silicon Chip
when the new session is added. So as
far as the user is concerned, the file is
no longer there – just as if it had been
deleted.
One variation of the multi-session
format is the CD-En
hanced (or CD
Plus) disc. This is handy when creating
a mixed mode disc containing both
computer data and CD audio. It lets
you “hide” the audio from the data
and vice versa.
Under this format, the audio tracks
are written during the first session
while the data tracks are written during subsequent sessions. An audio
player will then only detect the first
session and so will only play the audio. Conversely, a CD-ROM drive will
show only the data that’s recorded on
the disc.
Installing the hardware
We chose a Pentium machine with
PnP BIOS and Windows 95 as our test
bed for the Compro CD Recorder Kit.
Both the CD-R and the SCSI card are
Plug and Play (PnP) items, so they are
easy to install and get going.
Unfortunately, when we opened
the case, we didn’t have a spare power connector for the new CD-R. We
solved that problem by disabling our
existing quad-speed CD-ROM drive.
Before pulling the power connector
however, we booted Windows 95 and
removed the CD-ROM device driver
(just go to Control Panel, double-click
the System icon, select the CD-ROM
and click Remove).
Of course, there’s nothing to stop
you from keeping your existing CDROM drive if you have enough power
connectors. Indeed, this would be
desirable if your existing drive is an
8x speed (or higher) unit, for example.
The SCSI card plugs into a spare
ISA slot on the mother
board, after
which the SCSI cable is attached to
the internal SCSI connector. This connector is keyed, so the cable can only
be attached one way which is just as
well because the COMPRO Installation
Guide shows the colour stripe on the
wrong side of the cable (the Adaptec
Installation Guide is correct).
The CD-R slides into a spare drive
bay and is secured using the four
screws supplied. It’s then just a matter of plugging in the free end of the
SCSI cable and attaching the power
connector.
A minor niggle here is that no audio
cable is included for attaching the
CD-R to a sound card. This won’t be
missed by most people; an audio cable
is only necessary if you want to play
CD audio discs. You can still copy
audio CD tracks however, since this
data is sent via the SCSI bus.
COMPRO’s excuse is that they don’t
know what kind of sound card you
have but we think that a cable suitable for a Sound Blaster card should
have been included. The installation
guide also incorrectly shows the pin
connections for the audio socket, so be
warned if you intend buying a cable
from your local computer store. Fortunately, the correct pin connections
are clearly labelled on the back of the
drive itself.
When we rebooted the system,
Windows 95 automatically detected
the SCSI card and the new CD-R drive
and installed the appropriate device
drivers. If you don’t have a PnP system, it may be necessary to change
some of the settings for the SCSI card
to avoid a hardware conflict (eg, with
a sound card). You do that by using
the embedded SCSISelect utility. This
Fig.9: the “Multi Session” option must be enabled if you
want to add data to a CD-ROM over several sessions. The
verify and physical image options are also set here.
is accessed by pressing Ctrl-A during
the boot-up procedure, after which
you can change a range of settings,
including the IRQ channel and the
SCSI ID number.
You can also choose from one of
three termination options (Enabled,
Disabled or Automatic) and disable
the host adapter BIOS. In fact, Adaptec
recommend that you disable the BIOS
if the peripherals on the SCSI bus are
all controlled by device drivers and
do not need the BIOS.
By default, the SCSI card uses I/O
port address 340 and IRQ 11 and these
are also typically the default settings
for a SoundBlaster card. If this applies
to your setup, it will be necessary to
change the settings on one card to
avoid problems.
Using the software
The Gear pre-mastering software
comes on a CD-ROM which includes
both Windows 95 and Windows 3.1
versions (versions are also available for
OS/2 and the Mac OS). In addition, the
CD-ROM includes a comprehensive
manual on the Gear pre-mastering
soft
ware in portable document format (pdf) plus a full working copy of
Adobe Acrobat Reader 2.1 (to let you
view pdf files).
The first thing to do after installing
the software is to turn off any screen
savers and anything else that could
interrupt the recording process (eg, a
fax modem). For the same reason, the
manual also instructs you to turn off
the “Auto Insert Notification” option
for the CD-R drive and gives the step-
Fig.10: we initially had problems with buffer under-run.
Ditching the cyclical buffering option and selecting doublebuffering instead solved these problems.
by-step procedure for doing this.
The basic procedure for “burning”
a CD-ROM is clearly set out in the
manual. First, you have to choose the
CD type to be created (eg, CD-ROM)
and create a new image file (Figs.1 &
2) You then open the Gear Data Editor,
select the source drive and drag the
files you want to the My ISO Track
window. If you make a mistake here,
you just delete the track that you don’t
want from the image.
Closing the Data Editor now returns
you to the workbench, at which point
it is a good idea to run a test write. This
useful feature does everything except
actually write to the CD and is used to
confirm that the data throughput from
the hard disc to the CD is high enough.
You can also elect to automatically
write to the disc immediately after a
successful test and there’s a verify after
write option.
Alternatively, you can bypass the
test procedure and write straight to
the CD. A bargraph shows the progress
of the recording and the disc is automatically ejected when the procedure
is completed (as it is at the end of a
successful test run).
The Gear software is easy to use
although the Data Editor is a little
clumsy. First, it’s default window sizes
are too small and although they can
be easily resized, they don’t stay that
way when the Data Editor is closed.
Another problem is that the folders
on the hard disc are not presented
in alphabetical order. That said, both
these criticisms are fairly minor.
Sorting out the wrinkles
Our initial tests with small files
were successful but we quickly ran
into problems when we tried to write
large amounts of data to disc. These
problems centred around the type of
buffering used.
By default, the Gear software installs
with cyclic buffer
ing selected, as
Using Gear For Data Backups
A CD-ROM is useful as a secure
medium for backing up data and
Gear includes various archive setting
options to make the job easy.
By enabling the archives reset feature, the software will automatically
reset the archive bit for each file that
is loaded into the image. Any files
that are then subsequently modified
or created will have their archive bit
set again by DOS.
Provided that the archives only
feature is enabled, you can now simply drag all files across to the image
when writing the next session. However, only those files that have been
modified or created will be loaded
and added to the CD-ROM. Those
files that haven’t been modified remain in the previous session(s), thus
giving a complete backup.
Other options let you choose
whether or not to load hidden and
system files.
December 1996 13
Fig.11 (right): clicking the DiscInfor button on the Gear
workbench toolbar brings up this dialog box. This lets
you select and copy individual tracks (eg, from an audio
CD) to the hard disc.
Fig.12 (below): once the tracks are on the hard disc, the
virtual image for an audio CD is created in the same way
as for a data CD-ROM.
opposed to the alternative double-buffering option. During the recording
process, the buffer stores data from the
hard disc and streams it in a continuous fashion to the CD-R. If the buffer
runs out of data, any interruption to
the data stream from the hard disc
aborts the recording process.
With cyclic buffering selected, we
found that the buffer initially filled
(as indicated by a bargraph) but then
slowly emptied during the first few
minutes of the recording process. After
this, the hard disc really rattled along
as it attempted to keep up with the
demands of the CD-R.
When large amounts of data were
involved, the process inevitably fell
over. Once, we were about two thirds
of the way into writing 600Mb of data
when it crashed, despite a successful
test run. On another occasion, we
didn’t even get to the halfway point.
We tried everything to solve this
problem, including chang
i ng the
buffer size, writing at single speed and
even creating a physical image of the
14 Silicon Chip
files to be written. But no matter what
we did, the buffer still emptied after
just a few minutes and the hard disc
rattled its head off.
Unfortunately, initial test writes
with double buffering selected didn’t
hold much promise. Although the hard
disc now worked at a fairly leisurely
rate, the bargraph always showed an
empty buffer which didn’t even fill
before recording started.
With two dead discs sitting on the
table, it was time to call the local
COMPRO distributor. Their advice:
(1) ditch the cyclic buffering and
use double buffering; (2) create a
physical image of the data; and (3)
record at double speed. And the empty bargraph indicator when double
buffering is selected? Apparently,
that’s normal; it only works for cyclic buffering (it’s just a pity that the
manual doesn’t say that).
And that solved all our problems.
With double-buffering selected, we
successfully recorded large amounts
of data onto six CD-ROMs without
a hitch. In fact, with our setup, it
wasn’t even necessary to create a
physical image file. A virtual image
was sufficient, even when writing at
double speed.
Adding a new session
Adding a new session is quite
straightforward. You just insert the CDROM, click the Append button on the
Gear toolbar, edit the CD-ROM image
and write the data as before. The only
proviso here is that the Multi Session
option must have been selected before
any previous sessions were written to
the CD-ROM.
It’s important to realise here that
only the changes that you make to
the image are written to the disc. If
you want to keep a file, it must not be
deleted from the existing image. If you
do, it will appear as though the file has
been deleted. Of course, you might
want to “delete” files from a previous
session on purpose.
Each new session is added to the
disc using one of several “append”
Writing The Data To Tape
Instead of writing to a CD, you can use the Gear software to write
the data to tape. This tape can then be sent to a CD-ROM mastering
plant so that multiple CDs can be produced.
An unwanted by-product of this feature is that the Gear software
always looks for a SCSI tape drive when it is booting up and if it
doesn’t find one, comes up with the error message “No SCSI tape
units found”. This doesn’t create any problems but can become
annoying if you do a lot of archiving.
Fortunately, it’s easy to disable this feature by editing the gear.
ini file. You can do this is any ASCII text editor such as Notepad –
just look for the line TapeInterface = 1 under the [tape] section and
change it to TapeInterface = 0
options. Normally, for adding or deleting data, the Automatic Append option is used but there are also Manual,
New and Multi-Volume Append modes.
The Manual Append mode lets you select the track
you want to add data to and is useful for recovering data
deleted in a later session. By contrast, the New Append
mode writes an empty track so that all previous sessions
become inaccessible. Accord
ing to the manual, this
feature can be used to recycle a disc that has suffered a
write failure (presumably after a previously successful
session). Finally, the Multi-Volume Append mode is used
for creating multi-volume discs.
Making an audio CD
The procedure for recording an audio CD is slightly
different to making a CD-ROM, since you first have to copy
the tracks to your hard disc. First, you insert an audio CD
in the drive and click the DiscInfor button on the toolbar.
This brings up the dialog box shown in Fig.6, after which
you can select and copy individual files to your hard disc.
A separate dialog box prompts you to name each file just
before it is copied.
From there, the process is almost identical to creating
a CD-ROM, the main difference being that you choose
CD-Audio as the CD type before creating and editing
the image file. Another difference is that the recording
bargraph indicates the progress of each individual track
instead of the entire session.
In our case, we successfully created a test CD with 17
tracks. It played back on an audio CD player just like any
other CD, although we did notice a faint click between a
couple of the tracks.
As a point of interest, it is possible to create an audio
CD over several sessions despite the fact that an audio
CD is basically a single-session disc. You might want to
do this if you have limited hard disc space and cannot
load all the wanted tracks in one session, for example.
By now, you will have gathered that the Gear pre-mastering software is extremely versatile, with a host of features
– so many in fact that we didn’t have time to explore them
all. Despite this, it is an easy package to use.
In summary, our impressions of this CD-R kit are very
favourable. The complete package retails for $1295.00
and is available from Rod Irving Electronics, 56 Renver
SC
Rd, Clayton 3168; phone (03) 9543 7877.
MICROWAVE PARTS & REPAIRS
WARNING!: All microwave repairs must be done by a qualified microwave technician. All text
within is to be used as a guideline only. We recommend reading “MICROWAVE OVEN OPERATION
AND SERVICING MANUAL” (code: MAN-MICRO, cost $19.95) for full safety instructions. Shailer
Park Electronics will NOT take liability in any form for safety, health or work done.
MICROWAVE OVEN LAMPS
Hard to Find Range of Microwave Resistant Lamps
Code
Volts
Watts
Baseφϕ
$
CL818
240V
25W
13mm
$8.50
CL819
125V
25W
13mm
$9.50
CL821
240V
20W
15mm
$8.50
CL822
125V
20W
15mm
$9.50
Base φ
MICROWAVE SHORT PROTECTOR
Blowing mains fuse? This short protector may be
blown. It’s located across the high voltage cap which
holds approximately 2300V. This short protector can
be tested by first unplugging mains lead and then discharging the high voltage cap with a 1kΩ resistor.
The short protector can then be safely measured out of circuit. REPLACE SHORT PROTECTOR IF
FOUND DEAD SHORT. Code: 2X062H $14.95
MICROWAVE HIGH
VOLTAGE CAPACITORS
MICROWAVE HIGH VOLTAGE CAPACITORS
Code
Value
Voltage
Cost
Is your microwave oven blowing
the main fuse? The high
voltage capacitor may
be faulty. These
high voltage, low
tolerance capacitors are used in
microwave ovens
to complete a resonance circuit with the magnetron which is inductive.
A faulty capacitor may upset the lead-lag factor of
the resonance circuit and cause the transformer
to labour (hum) or blow short protector and/or
main fuse. The high voltage capacitor, which holds
approximately 2300V, can be tested by unplugging
the mains lead and then discharging the capacitor
with a 1kΩ resistor, after which it can be safely
measured out of circuit. REPLACE CAPACITOR IF
FOUND FAULTY OR DEAD SHORT
MWC65
MWC70
MWC83
MWC85
MWC86
MWC90
MWC95
MWC100
MWC105
MWC110
MWC113
MWC114-6
MWC120
0.65µF
0.70µF
0.83µF
0.85µF
0.86µF
0.90µF
0.95µF
1.00µF
1.05µF
1.10µF
1.13µF
1.14µF
1.20µF
2300V
2300V
2300V
2100V
2100V
2100V
2100V
2100V
2100V
2100V
2100V
2100V
2100V
$35.50
$36.50
$39.50
$36.50
$39.50
$39.50
$39.50
$50.50
$42.50
$44.95
$45.50
$44.95
$44.95
MICROWAVE OVEN ROOF LINING
Does your microwave throw sparks inside cavity? The roof lining may need replacing. This lining
is made of a special material to diffuse the microwave beam for even distribution. You will find the
lining if you open the door and look up inside the cavity; it is a flat sheet held in by screws or clips.
With age, the microwave beam will burn through this lining causing sparks inside. We supply 13cm
x 17cm sheet, simply cut and shape to size.
MICROWAVE OVEN ROOF LINING
Code
Type
Size
13cm
Price
MRL20
Microwave 13cm x 17cm $15.50
MRL50
Microwave 13cm x 17cm $17.95
17cm
MICROWAVE FUSES
Our range of original microwave
fuses are time delayed,
ceramic tube, with brass
nickel plated contact cups
and have a high breaking
capacity of 500A/500V.
Never use conventional
fuses as they may explode and shatter throwing
pieces of glass inside the food cavity, which may
be a health risk.
MICROWAVE FUSES
Code
Rating
Length
Price
AF010P
6.3A
5mm x 20mm
$2.50
AF011P
8A
5mm x 20mm
$2.50
AF012P
10A
5mm x 20mm
$2.50
AF019L
6.3A
6.35mm x 32mm
$2.50
AF020L
8A
6.35mm x 32mm
$2.50
AF021L
10A
6.35mm x 32mm
$2.50
MICROWAVE TURNTABLE BELTS
Code
Dimensions (A x B x C)
Length
Cost
MWB95
95 x 7.0 x 0.6
300
$11.65
MWB100
100 x 7.5 x 0.6
320
$11.75
MWB105
105 x 4.0 x 1.0
330
$11.80
MWB110
110 x 7.0 x 0.6
340
$11.70
MWB165
116 x 4.0 x 1.0
520
$15.65
MWB210
210 x 2.5 square
650
$14.95
MWB260
260 x 3.0 square
800
$14.90
MWB280
280 x 3.0 square
880
$13.30
MWB175
175 x 2.5 round
550
$19.95
MICROWAVE TURNTABLE MOTORS
Postage & Packing $3.50
SHAFT A
2.5 rpm
Code: MWM91
Cost $34.95
SHAFT B
5 rpm
Code: MWM16
Cost $36.95
ORDER HOTLINE: (07)
3209 8648. FREE CALL:
1800 63 8722. FAX: (07)
3806 0119
SHAFT C
2.5 rpm
Code: MWM159
Cost $39.95
SHAILER PARK
ELECTRONICS
KP Centre, Cnr Roselea &
Lyndale St,
Shailer Park, Qld 4128.
December 1996 15
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