A.C.E. 3/ACE CD 3.iso/files/docs/ppaint6d.lha/PersonalPaint6.4Ch10.doc

Text File | 1996-03-17 | 21.1 KB | 376 lines

          "Personal Paint  -  10. Problem Solving"

 10. Problem Solving
   10.1 Memory Shortage
   10.2 Problems with Disks
   10.3 Problems with Printers
   10.4 Problems with Screen Modes and Video Devices


10.        Problem Solving

   This chapter describes some of the most common problems which may be
encountered when using the computer and its peripherals, explaining how to
solve these difficulties, and what to do in order to prevent them from the
beginning.


10.1       Memory Shortage

   Computer memory is one of those few resources which, regardless of the
amount which is available, tend to be exploited to the limits. The most
common obstacles which may be encountered when using Personal Paint are
likely to be connected with insufficient Chip RAM.

   Sections 1.3.2 and 4.11 respectively contain important information on
RAM in general and on Personal Paint's Memory Information function. As
indicated in those sections, the information about memory which is
displayed on the Workbench title bar may be misleading, as it sums up
fragmented memory as if it were a contiguous block.

   A low memory condition may be signalled by an explicit message (e.g.
"There is not enough memory", or "Insufficient Chip RAM"), or by symptoms
like menus not appearing as usual, windows which cannot be resized or
repositioned, screen flashes indicating failures to accomplish a given
task, etc.

   Chip memory may be made available by freeing the undo buffer (selecting
the Undo tool with the right mouse button - section 3.1.10), clearing the
image twice (by clicking twice on the Clear tool - section 3.1.9),
choosing a screen mode having less resolution or colors (sections 1.3.2
and 4.5), freeing the current environment (section 4.8.5), freeing brushes
(section 5.6), freeing the stencil (section 7.2.7), switching off the
audio (section 8.4), closing the Workbench screen (section 8.16),
terminating other programs, etc.

   Typing "Avail FLUSH" in a Shell window, or selecting FlushLibs in the
Workbench Debug menu (which becomes available if the Workbench is
activated with a "LoadWB -DEBUG" command) frees all RAM-resident system
resources which are not being used any more. This may free some
considerable memory if several large fonts were used in previous sessions,
or if some complex libraries used by other programs are not needed any
more. When the system is in critical memory conditions, it usually
performs these actions automatically.

   In an emergency (e.g. if the main screen cannot be opened), Personal
Paint may automatically and gradually try to free some memory by taking
one or more of the actions mentioned above.


10.2       Problems with Disks

   The Amiga operating system may perform another disk write operation
some seconds after a file is stored. For this reason, a disk should never
be ejected from the drive (nor should the computer be switched off) for
some seconds after the disk drive activity indicator light has gone off.
Electrical noise can also cause problems. Lights, monitors and other
electrical devices connected to the same power line as the computer should
never be switched on or off while data is being written to the disk.

   Errors are first signalled by messages from the Amiga operating system,
and then by the program which is trying to save the data. The most
frequent sources of errors are: disk is write protected, disk is full,
disk is damaged or not formatted (sections 1.3.4 and 1.6). Unlike 5.25"
disks, 3.5" disks are write protected if it is possible to see through the
write-protect hole.

   If, while a file is being written to, the Amiga operating system
displays a message indicating that a read/write error has occurred, the
first thing to do is to eject the disk and set the write protect tab.
Precious data can be lost by trying to write to the disk after such an
error message. If the write protect tab is not set, the system may try to
write to the disk even if no write operation has been requested by the
user (especially if the disk is damaged). After the disk has been
reinserted, all the system messages should be cancelled with the mouse
(unless a "Software Error" message appears). The program which was saving
the data will display its own error message. The data which could not be
stored because of the error should be saved to another disk. Any other
material which is displayed or stored in RAM should be saved as well, so
that it can be recovered if its copy on the damaged disk has been
corrupted. Next, a copy of the damaged disk should be made (section 1.6).
If the standard system copy program does not work, because of the errors
present on the disk, other copiers should be used.

   A disk recovery program like DiskSalv will probably be able to restore
most files, with the likely exception of the one which was being written
to when the error occurred. It is possible that different disk recovery
programs will produce different results. The disk on which the error
occurred should not be used again, unless the cause of the error is known
not to be hardware dependent. An error may occur again on the same disk,
especially if a single sided or poor quality disk is used, or if the disk
is dirty, or the magnetic surface is scratched. Scratches are usually
visible when light is reflected from the disk surface. The surface itself
should never be touched or contaminated.

   Some minor errors are automatically corrected by a process of the Amiga
operating system called validating. If, for example, a write operation is
interrupted for some reason (e.g. a power failure, or the removal of a
disk), and no other damage occurs to the disk, the Amiga operating system
tries to validate the disk the next time that it is inserted in a drive
(or mounted, if it is a hard disk). The validation process can take a few
seconds or several minutes, depending on the size of the volume. If the
disk is write protected the validating process has to be repeated every
time the disk is inserted (or mounted). While the disk is being validated,
a "Disk not validated" system message is displayed if a program tries to
access that disk. The "Cancel" option of the message should not be
selected, as the message disappears automatically as soon as the
validating procedure terminates. It is possible to read from a disk which
has not been validated, but no data can be saved to it, since the data
structures which mark the parts of the disks which are free are not
updated.

   The most serious errors can be caused by physically damaged or
defective disks. The main cause of such errors is dirt. Coffee poured over
disks lying on the table, sticky drops of orange soda "raining" from a
nearby glass or a few grains of sand inside the disk case can be very
dangerous. Unless the magnetic coating of the disk has been scratched or
corroded, the data can still be recovered. Most liquids leave the cookie
(the foil coated with magnetic media inside the disk) intact, but must be
removed as soon as possible. The cookie must be taken out of the disk case
before it can be cleaned. To do so, a demagnetized blade can be used to
carefully open the case. The metal (or plastic) shutter of a 3.5" disk can
be removed by hand. The cookie can be washed under running water and dried
with a clean, soft cloth. The clean cookie can finally be inserted into a
new case (the shutter is not needed), from where it can be copied to a
new, intact disk. The procedure described here is not guaranteed to
succeed. Improper handling can damage the disk and/or the disk drive.


10.3       Problems with Printers

   Some suggestions to improve the quality of the printed output are
listed here. Possible solutions to many problems which may occur during a
print operation are also contained in this section.

   The parameters of the Amiga Preferences program must be perfectly set.
The most common cause of errors is the wrong choice of printer driver. The
printer driver specified in Preferences must be the correct driver for the
printer which is used. All printer settings of the Preferences program
must be correctly set and stored on the Workbench disk. Not all printers
use the same codes and control sequences.

   If the parallel port is used for a peer-to-peer connection between
computers (using a network filing system like "ParNet") then the Printer
Port setting in the Amiga Printer Preferences should be set to Serial, or
any device other than that used by the network. Use of the Amiga printer
device on the same line as the network might lock the network. Programs
like Personal Paint might need to access the printer device on startup,
even if no explicit printing is performed. Although no data is sent to the
printer by this process, this operation may lock the network and the
printer device.

   When the name of the printer driver has been selected with the
Preferences program, the programs which need to use the printer will be
able to use the correct printer codes, and Amiga will activate the
appropriate printer driver. Personal Paint's printer settings may be used
to change most system printer parameters, except selecting the printer
driver itself.

   By default, printer drivers are stored in the "Printers" drawer, which
is contained in the "Devs" drawers of the Workbench and Extras disks. The
Amiga operating system searches for printer drivers in the "DEVS:Printers"
and "PRINTERS" logical units. A driver stored only on the Extras disk must
be copied to the Workbench disk before it can be used. The InstallPrinter
program, on 1.3 Workbench disks, allows the user to copy the drivers from
the Extras disk to the Workbench disk in a very easy way. On operating
systems starting from version 2.1, unused printer drivers are placed in
the "Storage/Printers" drawer, from where they can be moved into "Devs"
using the mouse when necessary. Some of the most used printer drivers are
stored on Personal Paint's program disk. If that disk is used as the
Workbench disk, more updated or more specific printer drivers can be
copied to it.

   If there is no driver for a particular printer model, a similar or
compatible driver can be used. Most impact printers are compatible with
one or more of the Epson (ESC/P), Nec (Pinwriter) or IBM (Proprinter)
standards. Laser printers can generally work in the HP LaserJet and/or
PostScript standard. When more than one emulation mode is available, the
selection should match the selected Preferences printer driver. The
documentation enclosed with the Amiga and with the printer should be read
to determine which is the most suitable driver for a particular printer.
Appendix D of this guide also lists several suggested drivers for the most
used printers. The printer retailer or manufacturer should be contacted if
no information can be found in the handbooks, and the existing drivers do
not work. Drivers which were included with versions of the operating
system before 1.3, as well as versions labelled Alpha, Beta, Gamma and
Omega might not work properly with most software.

   The Printer Preferences program can be started with the mouse from
Workbench. If the screen has been closed, the Workbench parameter
described in section 8.16 can be set to open it again. If the Workbench is
still closed, the program should be terminated (section 4.12) to free the
memory necessary to open the Workbench screen.

   If text characters are printed instead of an image, or undesired
characters appear in the text printed by a word processor, the wrong
driver was probably selected. As an example, with some inappropriate
driver/printer combinations a 'P' or 'K' character (not part of the
document) is printed at the beginning of each print operation. The page
format (A4, Letter, Wide Tractor, etc.) must also be set correctly in
either Personal Paint's or the system's Page/Printer Preferences. Again,
it is not necessary to use the system Printer Preferences, if these values
are set through Personal Paint.

   When a print operation is interrupted (section 4.3), some printers may
continue to wait for the remaining image data to be sent. Software reset
commands, as well as margin, size and graphical data of subsequent prints
could be interpreted as binary data belonging to the first image. This
could result in subsequent images being printed at the wrong position, or
in the wrong size, or "trash" data being printed. To avoid this, it is
sufficient to reset the printer from its control panel (or switch it off
and turn it on again, if it lacks a reset function) after interrupting a
graphical print.

   Sometimes it may be necessary to change the default factory settings of
the printer. Some printers have small DIP-switches grouped into banks,
located at the rear of the printer or under the cover. Other printers
allow the user to change the parameters by accessing the printer memory
settings through the control panel. A parameter which is often not set
appropriately is the automatic line feed function, which should be
disabled to work with most printer drivers. This has to be done if the
graphic print is interrupted by wide horizontal lines, or if the line
spacing of the text is twice the spacing which was set through the
parameters of the word processor. If accents or other particular national
characters of a specific language are not printed, and the correct driver
was used, it is possible that the character set default setting (e.g.
"Italic"/"Epson" versus "Standard"/"IBM") or the language character set
should be modified. Personal Paint only prints in graphics mode, but
specific text-mode imperfections may indicate more general problems.

   If it is possible to choose between tractor (perforated paper) or
friction paper feed, it should be noted that friction feed is usually much
more accurate over short distances (e.g. single sheets), especially on
low-cost printers. On some printers friction feed may not grab a sheet
stiffly enough if the paper is too light or too thick (forcing the feed
mechanism). A discontinuous, asymmetric and imprecise paper feed may be
caused by the wrong paper type.

   The presence of thin, light, horizontal lines on the printed output
(graphic or text) can be reduced by selecting the friction feed and/or
narrowing the printer head to the paper. If the inked ribbon streaks the
paper, or dirties the margins of the paper, the printer head is probably
too close to the surface of the sheet. On some printers the presence of
thin horizontal lines can be reduced by selecting a Custom Paper Size,
and/or Single paper type rather than Fanfold in the Preferences program.
The internal power supply of some printers is not sufficient to guarantee
a homogeneous pressure of all needles on the ribbon. Some drivers may let
the printer use only part of their pins (generally the upper 16 of 24) if
some parameters in Preferences are set as described above. These drivers
make an improper (but surely appreciated) use of some Preferences
parameters, which would otherwise remain unused, like Paper Type. The
Threshold setting is also sometimes used for different purposes (like
adjusting color and lightness correction in the HP DeskJet printer).

   As strange as this may sound, graphics are often printed faster (and
with a higher degree of precision) in mono-directional mode than in
bi-directional mode. The mode can be selected manually or through software
control on most printers. Black and white graphic print is the fastest,
while gray level and color printing take longer.

   Some settings, like Smoothing, may be activated to reduce diagonal
"steps" in the graphic prints. This usually slows down the printing.

   On some color printers a black ribbon can (or must) be used to print
black text or black and white or gray graphics. In this case, only black
ink ribbons, usually more affordable than color ribbons, need be bought.

   If the printed colors appear different from what is displayed, it may
be useful to apply color, brightness and contrast corrections (section
7.1.4).

   A printing density which is too high (e.g. 300 to 360 dpi, rather than
50 to 150 dpi) may cause the printout to be too dark and smeared
(especially on ink-jet printers), as well as enhance undesired horizontal
stripes.

   Similarly, PostScript printouts may become too dark and have very
little different shades of gray when the density (LPI) is too high.
Section 4.3.3.3 has more on this. In case of doubt, the printer's default
values should be used (Personal Paint DPI and LPI set to 0, Default Spot,
angles set to a value greater than 360). The Moiré phenomenon, which
causes undesired patterns to appear, is discussed in section 4.3.3.11.2.

   Another frequent problem with PostScript printers has to do with the
serial connection between the computer and the printer. If the serial port
is used, some wires of the cable must be crossed and connected in a
different way than other, frequently used, one-to-one connections. To
allow for different types of handshaking and interactive operation, the
following wiring could be used: 1-1 (input and output pins with the same
number are connected directly), 2x3 (pin two is connected with pin three
on the other side, and vice versa), 4x5, 7-7, 6+8x20 (pins 6 and 8 on each
part are joined, and connected to the opposite pin 20). The other signals
are unused. On the software side, it is important that both the printer
and the computer use the same Baud Rate (usually 9600 or 19200), Data Bits
(e.g. 8), Parity (e.g. Even), Stop Bits (e.g. 1) and Handshaking (e.g.
XOn/XOff). These settings can usually be set from the Amiga Serial
Preferences and the printer's control panel.

   Finally, a warning addressed to the owners of Amiga 1000 models. This
computer requires a non-standard parallel printer cable. Connecting the
printer cable of another Amiga model, or a standard Centronics cable may
damage the equipment.


10.4       Problems with Screen Modes and Video Devices

   The main symptom of most of the problems described here are: a black
screen, flickering or unstable picture, monitor makes strange sounds and
impossible to select certain video modes or colors.

   With Amiga operating systems starting from version 2.0, it is possible
to specify the monitors which can be used. Each monitor has an associated
set of screen (or video) modes. This is important, as different Amiga
computers may employ more or less powerful or flexible graphic chip sets
and monitor hardware. All display modes which are supported by the
hardware and judged to be of good quality should be activated by copying
the associated Workbench icon into the "Wbstartup" (version 2.0) or
"Devs/Monitors" (version 2.1 and 3.x) system drawers. Otherwise, Personal
Paint would not be able to use those modes. Conversely, some video modes
could have been inadvertently selected. For example, having activated the
"Multiscan" monitor on an Amiga with a monitor capable of displaying only
NTSC or PAL pictures may produce unreadable displays when loading some
images. If this happens, the monitor files in excess should be moved back
from the "Wbstartup" or "Devs/Monitors" directory into "MonitorStore"
(Workbench 2.0) or "Storage/Monitors" (versions 2.1 and beyond).

   Images created on Advanced Graphics Architecture systems may not look
the same when displayed on earlier Amigas, even if the same amount of
colors is used. This is caused by the fact that more color combinations
are available for the color palette on AA systems. Personal Paint's
palette, color reduction and remapping functions will use the "coarser"
color resolution to guarantee a more correct representation of the image
if the Original or Advanced Chip Type options are selected in the boot
menu of AA systems.

   If a display card is used, and the screen does not appear to be updated
properly by some graphics operations, or if a system error occurs when a
new video mode is selected, the RTG option (section 4.5.5) should be
activated.

   Some graphics boards which make it possible to display screens in 256
colors or more have a color palette resolution of less than 24 bits (i.e.
less than 16 million colors). Since the standard for 256-color images is a
24-bit color palette, it may happen that images with such a color
resolution may not be rendered accurately by these cards. Personal Paint's
Remap function (section 7.3) can be applied after loading an image to
restore the original color variations. A sophisticated remapping technique
such as Floyd-Steinberg should be used (section 8.7).

   Double-Scan and other higher bandwidth video modes (as are generated by
Flicker Fixer and Display Enhancer devices) require an adequate monitor
(MultiSync/multiscan, VGA, etc.) to be displayed properly. The Flicker
Fixer or Display Enhancer may have to be disabled when using some of the
highest bandwidth video modes. At the opposite end of the range, the
original Amiga video modes (e.g. "plain" PAL or NTSC) may have a bandwidth
which is narrower than the minimum of some multiscan monitors. This is a
particular problem on Advanced Graphics Architecture Amiga systems, where
several, completely different, video modes may have to be used (and the
lower horizontal scan frequencies are not corrected by a Flicker Fixer or
Display Enhancer). Commodore provides special multiscan monitors capable
of handling most video modes. Other monitors may work, or may be
re-calibrated by a qualified technician to accept lower frequency signals
(typically, problems may arise at horizontal scan frequencies below 30 kHz
and vertical refresh rates below 55 Hz).

   Section 4.1 ("Load Image") has more on video modes.