Hexadecimal is merely another way of counting. In hexadecimal instead of
counting to the tenth number before adding an extra digit, you go to the sixteenth. The name comes from the latin 'hex' meaning 6 and 'deca' meaning 10 (10+6=16!). As we only have 10 digits ie. 0,1,2,3,4,5,6,7,8,9 to go upto 16 in one digit, we use uppercase (capital) letters for the extra digits. Hexadecimal numbers are often marked by an ampersand (&) to show that they are not a letter but a number.
We can count up but when we get to 10 instead of adding a 1 and going
back to zero we keep going with letters:
1 2 3 4 5 6 7 8 9 A B C D E F 10 11 12 13 14 15 16 17
18 19 1A 1B 1C 1D 1E 1F 20 and so on.
Inside the computer, it uses hexadecimal rather than decimal for many
activities. One of these activities is the storage of filetypes as a
hexadecimal number. When I refer to filetypes in the rest of this manual, I
will be referring to this number which denotes the type which the file is.
To make things easier on the user, Acorn included a labelling feature for
these filetypes so that we can set them or read them as text. For example if
you click the menu button over the 'manual' file, follow the entry
File 'Manual' >
across to the right, and go down to the 'Info' option, and again move to the
right, a window will open. In the 2nd line down it should read;
Type: Text (fff)
The word 'Text' is an example of such a label and the letters 'fff' are the
hexadecimal number for 4095.
Every filetype hexadecimal number has only 3 digits the largest being fff,
this means that there are 4096 (remembering &000) possible filetypes.
In the computers memory, each of these numbers can be represented by a string of text a maximum of 8 characters long eg. &FFB = 'BASIC' and &AFF = 'DrawFile', in most parts of typeinfo, the types are referred to as hexadecimal numbers, but in a couple of places strings can be used. Read the rest of this manual to find out about these locations (especially b10).
To confuse matters even more, some files don't have a filetype and are merely intended to be loaded into an address in the computers memory. These files if loaded into typeinfo will cause a message box to open, nicely informing you that the file has no type at the moment.
b2. Multiple uses
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In Filetypes by Mark Thompson on which this is loosely based, when a
filetype was used by more than one program, there was still only 4 lines of
information allowed. When analysing what improvements I could make, I
decided to provide a facility for such filetypes. Now, in the information
window there is an icon that says something like "Use 1:2" this means that
the currently displayed information is for the 1st out of 2 known uses. To
see the other uses simply click on the right or left arrows to go forwards or
backwards, respectively. Note that their is currently a restriction of 10
maximum usages so that memory is not overused by typeinfo. Also
remember, there is only one filesprite per type and it doesn't change with
the usage, perhaps in the future...
b3. The Iconbar icon
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If you click on this icon with the select mouse button, the information
window will be brought up and it will contain the information about the
last loaded filetype (the starting type is &FFF). If you click on this icon with the adjust mouse button, the editing window will be brought up and it will contain the last edited records data.
b4. The Information window
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There are several icons to the information window and at first glance, they
can make it appear cluttered. To start with the main purpose of the window
is to display information about the selected filetype. This filetype can be
selected in many different ways as outlined in the 'Loading Files' section
of this document.
Icon Uses
~~~~~~~~~
The icon at the very top-left of the window displays the filename of the
loaded file. Or at least if the filename is too long to fit in the icon, the last 52 characters of the filename. If you do not load a file and merely
search for data about the file instead of a useless out of date filename,
it displays the message 'Data search complete' to show that the search
has finished. If when you open the information window by clicking on the
icon bar before you have ever loaded a file or done a search the icon
will contain the message, 'Demonstration of operation', to show that no
search was done nor file loaded.
The next icon down displays a valuable bit of information. This icon
displays the filetype hexadecimal number as well as the File$Type name.
If the name is not available (has not been specified by any program) then
the window simply displays the message 'Unknown to the
computer' and then a dash and the hex no.
The arrows on either side of this box pointing left and right allow you to
easily display the filetype directly before or after the current one, by
clicking on the left or right arrows respectively. Or you can simply hold
down Ctrl and press either the left or right cursor arrows.
To the right of these two icon is a square icon. This will display the
filesprite if it has been already loaded into memory or if it is in the records.
If it is in memory but NOT in the records then it will still be displayed. If
however no spritefile can be found then the box will simply be left blank.
The next icon down is used to display the type of program that should be
using that filetype according to the Acorn allocation rules. This is useful
for if you are trying to decide on a filetype for a new application, you can
quickly and easily see whether your application's filetype is in the right
section.
Below this there are four borderless icons within one large one. These 4
icons hold the information that is loaded from the text record files. This
data can be edited in the edit window if you feel you can add something to
the comprehensive information already in place. This is probably the most
valuable part of the entire window as it
tells you what the file is what application can load/save it and where you
can get a copy of the application from.
Further down in the bottom left is an icon which will contain a message of
the form 'Use x:x'. This is in place for files which are used used by 2 or
more different applications. These uses of the same filetype I have dubbed
usage. The number to the left of the colon is the number of the usage
currently on display in the information icons. The number to the right of
the colon is the number of usages for this filetype. To the left of this icon
is two arrows pointing left and right, to see the next usage click on the
right one, to see the last usage click on the left one. If the currently
displayed usage is the first and you click to go back, there is no effect and
vice versa. If you click the adjust mouse button over either of these arrows,
then it does the action of the other arrow.
To the far bottom-right is the 'Edit' icon. When you click on this icon, the
record for that filetype is loaded into the editor and the information
window is closed while the edit window opens. You are now free to do
any editing you want on that filetype, to the data stored in the records. Or
alternatively you can simply press Ctrl-E.
Miscellaneous...
~~~~~~~~~~~~~~~~
The info window can be opened in 6 different ways:
• If the autoload option is turned on and you double-click
on a file without a run type the window will open.
• If you click with select on the iconbar icon, the window
will open displaying the information about the last loaded
filetype.
• If a file is dragged to the iconbar, the window will open
displaying any data that is available about that filetype.
• If you use the hotkey function where you hold down either
set of Ctrl and Alt keys and double-click on the file
the information window will open displaying data about that
filetype.
• Or you can edit the filetype into the 'Find Info'
window (found from the iconbar menu) and perform the search
