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Macintosh Computers



There are a number of Macintosh systems ("Macs") available in the department. Their use is normally on a first-come-first-serve facility for Chemistry undergraduates and postgraduates, although some courses do have priority. All these computers are fully "networked". Printers are also available, although you may have to bring your own paper and print cartridges. Opening hours are until about 21.00 during weekdays.
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Is the Computer Working or "Hung"?

If there is no screen display similar to this;

or the little "earth" icon in the top left does not spin round, there is probably a software or hardware fault on the system. All such faults should be reported to Sue Johnson (4567) or to Henry Rzepa (45774), along with the "name" of the Mac if you know it (ruthenium in this case). The cursor on a Mac is controlled by moving the mouse. If fails to respond to the mouse, the Mac may be "hung". The best way of "restarting" such a hung Mac is to hold down the following three keys simultaneously: The ctrl key (normally located on the bottom left of the keyboard) • (next but one to the right of it) and the "power" key (the key on the top right):

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On-line Help and Tutorials

If you have never used a Macintosh previously, and are unfamiliar with a "window" based computer, a short animated tutorial is available on the Macs themselves to illustrate the main points of operation. A "howto" describing how to invoke this should be available in the computer rooms. Everything that happens on a Mac is controlled by the "operating system", known also as the "MacOS". This brings help in the form of Macintosh Guide, Tutorials or Ballon help. Move to the item on the top of the screen, press the mouse button, and whilst keeping it pressed move the cursor down until it reaches Show Balloons or Macintosh Guide. The item will turn black, indicating it is selected. Whilst it is black, release the mouse button. The Guide will help you perform most actions on the Mac. Ballons will make most items you point to produce a small "speech balloon" containing a short explanation. This is a very good way to find out how a program works! After some experimentation, you will probably want to switch the balloon help off by reversing the procedure described above.

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Starting A Program

An option is normally achieved by locating over text or an icon and pressing the single mouse button down. For example along the top of the screen items such the File, Edit. special etc when selected cause further menus to appear. If you move to the spinning (it may instead look like ) on the top left, and press the mouse button, various "Apple menu" items appear.

The Apple menu () should contain entries for most of the programs you will be using. To start any of these running, move to the item you want, wait for it to turn black ("highlighted") and release the mouse button to invoke the item. Note that you cannot run the same program twice, but you can open several different programs simultaneously, up to the limit of the so-called "system" memory.
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System Memory and Storage Memory

This topic is introduced briefly now, since understanding memory and window management on a computer is essential to making further progress. Let us first attempt to distinguish between the fast (responding in around 70 ns) internal but temporary system memory of the computer (typically between 8-32 Mbyte in size) and the external much slower (responding in around 10ms) but larger (typically 250-2000 Mbyte) and more permanent hard disk storage memory on which the programs, or "Applications" on the Macs are stored. A "byte" on these machines represents one character or numeral of a document or application, or one "pixel" on a 256 colour screen. It takes about 3-30 seconds to transfer a program from the slow hard disk to the fast system memory. It resides there only while the computer has power, and there is a limit to how many different programs can be transferred in this manner, bearing in mind that "MacOS" already occupies about 4-5 Mbytes of this memory! If the previous user left a program running, the program you wish to run may not have sufficient system memory to operate, resulting in confusion all round! To cope with this, we have to introduce the concept of applications, their windows and their status.
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Screen Windows.

Each program running can be associated with a window on the screen . A program need not have any open window at all, or its window may be hidden underneath another window. To find out for certain if anything is running, point the mouse to the small icon on the right of the and press the mouse button, but do not release it yet. A menu appears showing the running applications;

In this example, two applications are running, with the foremost window corresponding to the application with the tick. By foremost we mean that most keyboard entries and mouse clicks are associated (or "focused") on that particular program and any windows it may have. There are several simple ways of focusing on a program or its window;
  1. With the menu above active, move the cursor down to the one you want and now release the mouse button, whereupon its menu entry turns black and then that program and its window(s) come to the "foreground". At this point, the little icon to the right of the changes to represent the active application.
  2. Selecting "Hide Microsoft Word" in the menu above temporarily remove all windows associated with Word from the screen and focuses on the next program in the list.
  3. If a program does have a visible window, simply "clicking" inside the window will focus it.
Information about the focused program can be obtained by moving the cursor to or and selecting the "About ..." item at the top of the menu. One application that is always running managing the memory, the programs and their windows is called "The Finder". When Finder is active, its window is called "The Desktop", on which you get to see various "Folders" containing programs or documents and any disks or "file servers" that may be "mounted". The "About ..." item in the Apple menu for Finder gives you an "About this Macintosh" entry;

This tells you what other programs are running and most importantly how much memory for new programs is left. If there is insufficient memory for another application, you will get a message of the type;

which enables you to quit any applications that have no open windows. If all the programs running do have open windows, you will have to close one or more down manually. Switch to a program you do not wish to use as indicated above and select Quit from its File menu as shown above. Quit as many programs as necessary to make your own application run.
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Command Key shortcuts

You will notice from the above menu that Quit can also be invoked by pressing simultaneously the key labelled • with Q. Many such shortcuts are described in the pull-down menus and as you become more confident, you will use them more often.
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Opening and handling a Document

Now that we can be sure of having enough memory to run an application, we can consider how to manipulate "documents" associated with the application. These are normally stored in "Folders"which are opened by performing a "double-clicking" operation on them, of which five desktop folders have been created for you. The only one whose contents you are allowed to alter is the "Users Folder". Anything saved in other folders is liable to be deleted without warning.

Files or "documents" on the "desktop" or in a folder can be renamed, duplicated, deleted, "aliased" or "shared" from the File menu of The Finder if their icon is selected (highlighted or black).

This is done by a single mouse click on the item to "highlite" it. When a "document" is "double-clicked", it will instead open to a window associated with the program that created it, provided that application resides on the hard disk. A common misconception is to assume that a document created say on a Mac in one department will necessarily open on the Mac you happen to be using. It may not because no license for the application is available on the Mac you are using.
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Chemistry Software.

The Chemistry Macs have a number of programs available for general use. Please remember that copying software without a valid license is illegal. Some of these programs are shown below;
Claris WorksAn integrated word processor, spreadsheet, database, drawing program
ChemDraw Chemical structure diagrams
ISIS/DrawAn alternative Chemical structure program
gNMRNMR Simulation Program
CACheMolecular Modelling programs
MathematicaMathematical package
Cricket GraphGraphs of numerical data
Curve FitLeast Squares Curve Fitting
MacX X-Window communications program
Telnet Terminal emulation program
EudoraElectronic Mail program
NetscapeWorld-Wide Web program

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Finding Files

It frequently happens that you loose track of a file, or you want to know if a particular program is available to you. The best tool for solving this problem is found by selecting "Finder";

and then from the File menu, "Find...";

The search criteria can be altered by pressing the "alt" key (found between the ctrl and the • keys) and then clicking on the selection criterion. A whole range of options is offered to you, including one called "content", which allows you to search for text strings inside documents.

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Macintosh Virus Protection

Viruses are pernicious "programs" which were written solely with the intent of damaging the software resident on a computer. They appear on your computer almost always via insertion of a floppy disk containing "infected" software. The user is not normally aware of the infection until the computer starts misbehaving, ie programs stop working normally. All departmental Macintosh systems have "anti-viral" software called Disinfectant, which automatically detects infected programs and either deletes the virus or informs you of its presence. The system is nevertheless not completely foolproof, and depends to some extent on having an up-to-date version of Disinfectant (Version 3.6 in September 1995).
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Over a period of time some fairly dubious files tend to appear on the hard disk. Other essential files have a tendency to disappear, or to get moved into misleading folders. In order to maintain these systems in working order, a program called RevRdist is run about once a week. This compares each "client" Mac with a central "clean clone" and tidies the former up. If you have saved some files on the Mac disk, they could well be purged by this process unless they are in the "Users Folder". Anything that you do not want purging should be stored there, preferably associated in a folder bearing your name. Even so, there is nothing to prevent anyone else from deleting these files, and the best solution is to store all your own stuff on a floppy disk. To repeat again, NEVER assume that any files left on a Macs will still be there when you come back. Files kept in the Users Folder are much safer than files left anywhere else, but if the disk has problems, they too will vanish.
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Initialising a Floppy Disk

It is suggested that your personal files should be stored on a 3.5" (1.4Mbyte, HD) floppy disk, costing about 1 pound each. Get at least three disks from the Computer Centre shop on level 4, Mechanical Engineering. Before you can use them, the disks have to be initialised. Check that the disk drive is empty (!) and insert the disk with the label side up and the metal shutter pointing away from you towards the disk slot. You will be informed the disk is not initialised, and you should format the disk by clicking within the "double sided" box and then entering a name for the disk. When this process is completed, a little disk "icon" bearing the name of your disk will appear on the right hand side of the "desktop" below the hard disk icon, and the disk is ready for use. Look after your disks, do not get dust inside them, and avoid getting them wet in the rain.

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Backing Up Your Work

Every five minutes or so, you should update the disk contents by selecting Save from the File menu of the application you are working in (• and S). Remember that if the Macintosh "hangs" (normally indicated if the or other cursor freezes) or some other fault develops, the entire contents of the fast volatile memory will be lost. Normally, the disk version of your document will still be useable, and if you have updated it frequently, you will not lose much work. However, even hard or floppy disks can "go bad". Most people encounter about one bad disk every six months. Murphy's Law states that this will almost certainly happen the day before you are due to hand in a vital report!. It is strongly advised that for every one hours work, you write out your document to a second floppy disk. Select Save as... from the File menu and then Eject your working disk and insert a second one. For even more security, you should rotate three disks in this manner. You should write every one days work to a floppy disk and then "Write Protect" the disk by moving the little 3mm square plastic lock at the bottom of the disk so that a hole is exposed in the disk. This eliminates the possibility of accidentally deleting or reformatting the disk, or of a rogue program damaging the disk files in some way that makes them unreadable (this actually happens to unprotected disk surprisingly often, again almost always when a vital report is due).
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Selection and Editing.

To understand how to edit, we must extend the concept of a "selection". Text and graphics within a document can be selected and in this state can be "copied" to a temporary storage location known as the "Clipboard". The clipboard is common to all programs, and hence serves as a means of moving around data within the same or different documents (a more permanent form of the clipboard is called the "scrapbook", and can be invoked from the Apple menu items). Move the cursor with the mouse to the start of some text to be selected, press the mouse button but do not release, move the cursor to the end of the text to be selected, and release the button. The text goes black (or some other colour on a colour system). Whilst so the "attributes" of the text can be modified, ie it can be deleted, changed in size, italicised, the font changed etc, or in some word processor such as Word "dragged" to a new location. If you have made a typing error at any stage, the error can be corrected by selecting the text to be replaced and immediately typing the corrected entry. This is an area where command key shortcuts are particularly useful (• with X, C, V). A newer alternative to copy-n-paste is "drag-n-drop" editing. A selection of text or graphic is made as usual, and then this item is "dragged" with the mouse from its old location in one program to its new location in either the same window or another window or even program. Not all programs support this feature however. Also on the horizon, and expected to be introduced during 1996, is the idea of a "compound document". This dispenses with the idea of applications between which data has to be moved, and focuses instead on a single document. As each component of a document is selected, so the toolbar at the top responds to the selection and changes. Thus in effect the text, images etc are actually staying put, and its the applications that move around! The user has to do nothing! The "drag-n-drop" metaphor is still used for moving data from one document to another of course.
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Printing is normally carried out from within the applications. Check that the printer selected is one of the several HP Deskwriters available for undergraduates by Selecting Chooser from the Apple menu;

If you are only printing one document, its faster to do this with the background printing set to off. Sometimes when background printing is on, the computers have a tendency to hang! Check also that the printer has an Ink cartridge inserted as well as paper.For higher quality, use Croxley script paper. Do not select any other printer; you will not get any printout back and someone else in the department might get very irate! Close the Chooser window and go to Page Setup from the File menu of your application. The display should show the type of printer you have selected, the page size (normally A4) and its orientation.

Select Print from the File menu.

This will verify which Deskwriter you have selected. Unless you are printing the very final version of your document, select economode mode for faster printing. The print job will be "spooled" to a hard disk file and should start printing immediately if you have background printing off. You may have to join a queue on the printer, so if nothing happens immediately, be patient. If no printout appears at all, you have probably printed on another printer and someone else is probably cursing you for wasting their paper. If you have selected background printing, you can find out the progress of your printing job by seeing if a program called HP Print Monitor is running. Remember, if there is insufficient system and disk memory on the Mac available, this program may well not be able to run. Colour printing is not available.
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Ending Your Session using a Program.

From the File menu of any application, select Quit to exit. If you have not recently saved your work, you will be reminded to do so. Remember to eject your disk. Position the cursor over your disk icon, press the mouse button, and whilst keeping it pressed, "drag" the icon to the wastebasket. As it moves over the wastebasket, the latter will become dark. When this happens, release the mouse button. At this point, your disk will eject from the drive and you can now take it with you. Do not switch the Mac off unless you are the last user at night.

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Interchanging MS-DOS and Macintosh Files

If you wish to interchange MS-DOS and Macintosh files, format a 3.5" high density (1.4Mbyte) disk in MS-DOS format and insert it into a Mac. It will be automatically recognised as a PC disk and mounted on the desktop. From here, you can treat it as a normal Mac disk. Disks formatted on a PC will be automatically recognised, and you need not take any further action to process them.
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Copyright (c) H. S. Rzepa and ICSTM Chemistry Department, 1994, 1995.