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Browsing the Web with HyperLink
HL2.5's online mode
HyperLink 2.5 seamlessly switches between online and offline modes. When
you click on a link that points to a file on the current disk, or back
up or use the history screen to back up to a file on the current disk,
or click the open icon and enter a filename (registered users only), HyperLink
shifts to offline mode. When you click on a link that points to a Web page,
or back up or use the history screen to back up to a Web URL, or click
the open icon and enter a Web URL (registered users only), HyperLink shifts
to online mode. Gopher URLs also automatically enable online mode (see
Browsing
Gopherspace with HyperLink).
Online documents are not permitted the same operations as offline documents.
Online documents can never install machine language subroutines
or access memory, so the CTRL-K combination is not needed for the
Web. Online documents may display I3-format inline images, but they must
already be on the disk in the primary disk drive (for this reason, most
images are displayed by themselves). Also, the help, home and about icons
still reference files on the disk in the primary disk drive, not anything
online.
The first time HyperLink switches to online mode in a session, it must
connect to your Internet service provider. You will be placed in terminal
mode. The terminal program is a dumb 40-column terminal (no VT100 support)
and is designed to allow you to send AT commands and/or log into your ISP.
If you have a null modem connection to a Unix server, log into your
server in the manner you have the connection configured through your RS-232
interface.
If you use a modem to connect to your service provider, then you will
need to use AT commands to dial into your ISP; for example, to dial the
phone number 555-1212, you might type "ATDT 5551212" (without the quotes).
Follow your Internet service provider's instructions to dial your ISP,
then log into your shell and get to your shell prompt. Contact your ISP
if you need help with this step.
Make sure you are in the directory in which you installed HLPP; if this
was your home directory, type cd to make sure you are in the right
place.
Start HLPP by typing hlpp at the shell prompt. If this doesn't
work, try ./hlpp by itself with a leading period and slash.
HLPP will run a brief self-test and find the utilities it requires, and
then prompt you to press F1 to tell HL2.5 that the proxy is ready. When
you see this message, press F1, and then press F1 to indicate to HyperLink
that the connection was successful (if you encounter an error, press F7
instead and try again from the beginning). You are now connected to the
Internet, and when HyperLink encounters a Web URL, it will automatically
request the page from your Internet service provider. To check your connection
status at any time, press the = (equals sign) key to view your current
location and history. Your Internet connection status will also be shown.
While web pages and images are downloading, a transmission icon appears
in the lower left. This icon will display a pattern of flashes or lines
while data is being downloaded. Normally, it should alternately show green
and black while data is being transmitted. Flashes of pink indicate corrupt
data and may be signs of a bad connection. Whenever the transmission icon
is showing, you can press CTRL-COMMODORE at any time to break the link
and display what portion of the picture or image has been transmitted so
far. This is also useful if your connection seems to be "stuck" due to
line noise. When the web page has been completely transferred (or you break
the connection), it will be displayed. (Please note that incomplete pages
may be saved in your cache. Use CTRL-R to reload them later.)
HLPP operation over the Web
HLPP is a general purpose Internet proxy and offers multiple Internet access
protocols. This information below applies specifically to World Wide Web
access.
HyperLink can view any LinkScript document directly -- since this involves
no conversion, this is the best approach. Documents with a MIME type of
application/x-hyperlink
are forwarded on to HyperLink without any further modification (except
to strip active content from them, which is never allowed when HL2.5 is
in online mode).
However, because HyperLink does not interpret HTML or .JPG/.GIF/.TIF
images directly, it relies on HLPP to translate these files into LinkScript
and hi-res images on its behalf. Thus, web pages and images may look different
in HyperLink than they do in other web browsers. Here are the key differences.
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Some characters in URLs don't exist on the C64. When entering a URL directly
(registered users only), use %7E for the tilde (~), and the backarrow
(<-) for the underscore (_) character. These in turn will be displayed
this way on screen.
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Online documents, except under the single exception noted previously, cannot
display inline images. However, you can still view the .JPG,
.TIF or .GIF images they reference separately. Whenever an image is encountered,
a placemarker is displayed (either [IMAGE] or the "alternate" text
specified by the page author), and then below it two options to the far
right: <View image> and <File options>. If you click
<View
image>, the screen will clear and HyperLink will try to display the
image. The image will be reduced to black-and-white and automatically reduced
in size to fit your screen if needed. When the image is completely displayed,
the pointer will appear. Click the button. After a brief pause, you will
be returned to the exact spot in the document you were at previously. If
you want to download the image, or get information about it, click <File
options> for information about the image (usually its size and type)
and a list of options (usually view or download the file). You can press
F7 to back up from that point. See the information on downloading files
below. This can be turned off from the HLPP settings page (see below).
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HyperLink tries to pick the closest colour match to those
used on the web page. This means colours might not precisely resemble those
specified because of the C64's 16-colour palette. You can turn this off
from the HLPP settings page (see below).
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There are no equivalents for tables or frames in LinkScript,
so HLPP tries to translate them. HLPP handles tables similarly to older
versions of Lynx, treating table cells like paragraphs. It also handles
frames similarly to Lynx, turning them into links you can click on.
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HLPP will attempt to turn forms into searchable documents
(this only works for single-input GET forms, which is the majority of forms
in search engines and the like). These look just like <Searchable>
documents to HyperLink and can be searched with the S key. POST forms and
form file uploads are not supported. The type of form HyperLink sees will
be displayed.
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There are no equivalents for JavaScript or Java in LinkScript.
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Since HyperLink is 40 column, documents formatted for 80 columns or larger
will appear strangely wrapped.
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In online mode, HL2.5 has a 16K page buffer. However, this does not translate
into 16K of HTML, because LinkScript tags are in general much smaller than
their HTML counterparts, and HLPP also throws away tags HyperLink can't
use (like applets, JavaScript, <select> blocks, etc.). Thus, even pages
as large as 32K of HTML can be distilled down and viewed comfortably by
HL2.5 under optimum circumstances. Nonetheless, there will be some pages
too large for HL2.5 to view. In these cases, the first 16K is transmitted,
along with a link at the bottom allowing you to download the HTML to disk
for use with any offline HTML viewer (not HyperLink). Fortunately, many
pages will fit comfortably into memory.
HyperLink also supports WAP/WML mobile Internet-style pages served over
HTTP. These pages are often much smaller and faster to download, and are
specifically designed for low-power text clients like HyperLink. Please
note that many WML features are not supported, including ECMAScript and
forms, but the majority of features, including WBMP images, are. These
pages look to HyperLink like any other web page.
HLPP offers various options you can use to control how it translates
HTML and WML pages into LinkScript. The <HLPP settings> link
on the top upper right of each page displayed takes you to its control
panel, where you can adjust the settings. The BODY colours option
controls whether HLPP tries to use the document's colours or its internal
set (fonts that are displayed in different colours still are -- this only
controls global settings). If you don't like the way HLPP selects colours,
click this to toggle it on or off. The images option controls whether
you receive the <View image> and <File options> options
on every image. If this is annoying on particularly image-heavy pages,
you can turn these off (and since it makes pages smaller, it will help
fit more of the page into memory and reduce download time as well). Click
Go
back to the previous page to resume with your new settings. Note that
old pages still in your cache might have to be refreshed with CTRL-R.
<HLPP settings> does not affect LinkScript pages that HLPP
does not translate. Thus, LinkScript pages can always use their own colours
and images (it is assumed the page is tested on LinkScript and works appropriately).
Terminal mode
While you're connected to the Internet, the F4 key is also enabled. Pressing
F4 drops you into terminal mode and gives you your shell prompt again.
At this point, you can use the terminal to do file maintenance or send
Unix shell commands to your server. You can either log out of your server
and shut down your Internet connection at this point, or restart HLPP and
resume browsing the Web. To log out of your server, log off your account
and disconnect from your server following your Internet service provier's
instructions. To resume browsing instead, simply restart HLPP as you started
it originally. Either way, press F1 when ready, and press F1 again to stay
online or F7 to signal HyperLink that you have disconnected. If you remain
online, HyperLink returns you to the exact spot in your document where
you were. If you disconnect, HyperLink will send you to the home script
on the disk in the primary disk drive as if you had clicked the home icon.
(Speaking of which, clicking the home icon or pressing F5 while online
clears your history and your cache, but you remain connected.)
The terminal program is not designed for sophisticated tasks, but it
does allow you to send some control characters and do commands that don't
require terminal emulation. In terminal mode, the DEL key sends BS (ASCII
8); SHIFT-DEL (INS) sends DEL (ASCII 127); and RETURN sends LF (ASCII 10).
To send ESC, type CTRL-[. To send TAB, press CTRL-I. Use <- for an underscore,
the English pound sign for backslash, and shift-+ for a pipe symbol. Most
CTRL-key combinations are enabled. If you appear to be getting junk displayed
to your screen, try setting your terminal type to dumb following
the instructions of your Internet service provider.
Downloading programs and files
When you click on a link that points to a program, a software archive,
or some other file that HyperLink can't display on screen, it will instead
tell you about the file and give you the option of downloading it. You
can download any file up to 1MB in size. When you click the option allowing
you to download the file, it will prompt you for a filename. Insert a disk
into the primary disk drive to hold the file, if needed, and then enter
a valid filename. The file will then be downloaded to disk. Follow the
prompts on screen, if any. When the download is complete, you will be returned
to the exact spot in your document where you were.
While online, you can also access files on your shell server. (Because
this involves entering a URL directly, this is only available to registered
users.) For example, say your home directory on your server is /home/myaccount
and you have saved a file mypicture.jpg in that directory. Press
F3 or click the open icon, and type http://localfile followed by
the absolute path to the file (in our case, http://localfile/home/myaccount/mypicture.jpg).
HyperLink will access the file and either display it, or present you with
options to view and/or download it to your computer. Please note that the
extension is critical. If HyperLink cannot find a file extension, or the
extension isn't recognised by HyperLink, you can only download it and can't
view it. Likewise, an incorrect file extension might confuse HyperLink
and cause it to present inappropriate options that might not work properly
on the file.
Tips for faster Web browsing
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Use the fastest modem available (duh :-).
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When sites offer a text-only mode, use it. These pages are smaller, so
they are more likely to transmit more quickly and more completely, and
are usually formatted to allow browsing with Lynx which HLPP attempts to
emulate. This is particularly true of WML pages, which are small, fast,
and designed for text browsers, as well as Gopher sites (see Browsing
Gopherspace with HyperLink).
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Turn off the images option in <HLPP settings>. On particularly
image-heavy pages, this can reduce page size as much as forty percent.
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The more cache memory you have available, the less HyperLink will need
to fetch pages from the Net.