Archive Magazine CD 1995

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Text File | 1991-12-07 | 15.8 KB | 301 lines

%OP%DP0 %OP%IRY %OP%PL0 %OP%HM0 %OP%FM0 %OP%BM0 %OP%LM4 %OP%FX %OP%FY %OP%FS %OP%PT1 %OP%PDPipeLine %OP%WC834,2070,164,1620,0,0,0,0 %OP%VS4.01 (22-Oct-91), Gerald Fitton, R4000 2915 6625 6368 %CO:A,72,72% %C%Printing %C%by Gerald L Fitton Keywords: Printing Characters Fitton Introduction In this article I shall try to describe the relationship between what you type at the keyboard, what you see on the screen and what gets printed on the printer. Before doing so I think I should say to those used to such machines as the old BBC B with say Interword that the PipeDream program (like many applications on many machines such as those of the MS DOS range) does not contain its own character set nor its own printer driver but PipeDream lets you, the user, install any character set and any printer driver you want to (or can) use. To many people this division of responsibility for the use of the application presents a problem that they did not have on their old machine with their old software. In particular it is usually a mistake to blame PipeDream if your Printer Driver doesn't print out what you see on the screen. I hope this article will help you to understand how you can benefit from the flexibility that this approach gives you when you come to upgrade your software such as when you include user defined system fonts or buy extra outline fonts or get a laser or DeskJet to replace your 9 pin or daisy wheel printer. Character Sets There are eight bits in an 8-bit byte. These bits are rather like eight switches that can be on or off. The 256 different combinations of these switches can be written as 00000000 to 11111111 in binary, or &00 to &FF in hexadecimal or from 0 to 255 in the scale of ten (denary). Every character in a character set is given a unique code number between 0 and 255. There are 26 letters in the English alphabet, or 52 if you count upper and lower case letters separately; as an example capital 'A' is code 65. There are ten digits from 0 to 9. If you add to these 62 characters all the punctuation marks such as a full stop, and not forgetting the space (code 32) you will find that there are 95 printable characters all together. These 95 printable characters are coded from 32 to 126 and can be entered directly from the keyboard. Code numbers from 0 to 31 inclusive are reserved for special screen or printer effects such as moving the cursor left (code 8) or right (code 9). Code 10 moves the cursor down a line or causes a line feed at the printer. Code 13 causes the cursor to move to the left of the current line. Pressing <Return> causes both a code 13 and a code 10 to be sent to the screen drivers so that the next character to be printed appears at the left end of a new line. Code 127 is the <Delete> key. In addition to these 128 characters there are another 128 characters with code numbers from 128 to 255. These are called 'top bit set' characters (because the first binary bit of the 8 bits is set to a '1'). The character produced by any of these top bit set characters depends on the character set in use at the time. The default character set is Latin 1 but there are others such as Bfont and Greek of which more later. These top bit set 128 characters can be entered from the keyboard by holding down the <Alt> key and typing in the code number on the numeric pad or by using the !Chars application provided by Colton Software. For example, in Latin 1, you can get the character µ by holding down <Alt> and typing in the number 181 on the numeric pad. When you release the <Alt> key the character µ appears on screen. As an alternative, you can double click on the !Chars application which is provided by Colton Software with PipeDream. When you do this the current character set is displayed in the system font in a window called Characters; you can change this character set with a command such as *Alphabet Greek (press <F12> to initiate a * command). If you change the character set in this way then any top bit set characters will be displayed in the new character set in the PipeDream window as long as you are using the system font. When you click on any character in the Characters window then that character code will be entered into the PipeDream window at the current position of the cursor and the same character will be displayed in PipeDream as in the Characters window so long as you are using the system font. Translations On the HP and IBM range of printers the character set which has the nearest correspondence to the Acorn Latin 1 is ECMA-94 Latin 1. If your printer has this character set resident then you will find that the PipeDream printer driver, HPjet, selects this character set. If your printer does not contain this character set then it probably defaults to a character set known as Roman 8. Roman 8 requires translations for the often used £ as well as characters less often used such as ¢, §, ©, ®, ±, µ, ß, ×, ÷, ¼, ½ and ¾ and foreign characters such as á, è, ï, ð, û, Ç, ç, Ý and ¥. Fonts Acorn originally issued fonts called "Fancy Fonts" with the Archimedes. These so called "Fancy Fonts" are bit mapped (as sprites) and are generally more trouble than they are worth. If you intend to use fonts other than the system font on screen and the fonts resident in the printer then you should upgrade to "Outline Fonts" such as those on our DrawPlus disc rather than the bit mapped "Fancy Fonts" supplied originally by Acorn. The following paragraphs refer to Outline Fonts and not the original bit mapped fonts originally supplied with the Archimedes. If you choose to display in some other font (such as Acorn's outline font Trinity.Medium) then the character codes are translated into pictures on the screen according to the way in which the font is defined. All Acorn fonts (except Selwin) use the Latin 1 character set so, whatever *Alphabet you have used (eg *Alphabet Greek), the display will be in the Latin 1 character set. I suggest that you use the system font (this file and nearly all other files on this disc use the system font) with the PipeDream printer drivers and only use the outline fonts with the RISC OS drivers. The default for PipeDream is that the system font is displayed on screen but the RISC OS driver is selected. If you intend to use the PipeDream printer drivers only then you should set up your Print - Printer configuration - Printer type as Parallel and select the name of your printer driver (DotMatrix) in the printer driver dialogue box as described in the next paragraph. PipeDream Printer Drivers What happens when you Print from PipeDream depends on whether you are using a PipeDream Printer Driver or a RISC OS Printer Driver. Taking the PipeDream Printer Driver first: The printer driver is installed using <CTRL PD> (Printer Driver) or from the Print menu. Select as the type of printer Parallel (or Serial) but not the RISC OS driver. In the next row select the name of the file containing the PipeDream Printer Driver you wish to use. Press <Return> and this printer driver will be loaded. We have quite a few donated by PipeLine readers which are on the July 1990 PipeLine disc but your choice from those supplied by Colton Software are DotMatrix for the Epson fx80 and similar printers, HPJet for Hewlett Packard and many IBM printers, DaisyWheel for the Juki and BJ10 for the popular Canon Bubble jet. When you use a PipeDream Printer Driver and send a file to the printer it is the code numbers (such as 65 for an 'A') which are sent to the printer; how they are printed depends on the character set which is resident within the printer. Many printers have the same English characters for character codes 32 to 126 but they do not use the Latin 1 character set for the top bit set characters. Some printers support the IBM character set which has some graphics characters. On the Epson FX80 and many other dot matrix printers it is possible to redefine the matrix of dots which are printed when a top bit set character code is sent to the printer. In the Printer directory of the July 1990 PipeLine disc I have included a set of character definitions for an FX80 which print out the same characters as the *Alphabet Greek character set. The character definitions are in the form of a BASIC program and all you need to do to download the definitions to the printer is to click on the BASIC program 'Greek' so that it runs once. The BASIC program also executes the command *Alphabet Greek so that the Characters window called up by !Chars will display the Greek characters which will then be printed out by the Epson FX80. One word of warning. Many printer drivers for the Epson FX80 (including DotMatrix supplied by Colton Software) have a Printer ON string (PON) which resets the printer and so clears all the definitions you have downloaded. I have included an FX80 driver on the July 1990 PipeLine disc called FX80Pica which avoids this potential problem. Use it in conjunction with the Greek program if you want to print out Greek characters on an FX80. Many of you have asked how to increase the number of printer highlight codes available to obtain, say, expanded printing or double height characters (supported by the Star LC24-10). Typically I have a letter from a PipeLine reader who has defined a set of SPD(n) - SPD for Star Printer Driver Commands "From Appendix B" - and types in SPD1 etc in the first column of his printer driver. This does not generate the desired effect. Probably the best method of achieving extra printer effects is to type a 'top bit set' character into the text and then, in the printer driver translations of the printer driver file, type the same top bit set character in the first column (where our reader has typed in SPD1 etc) and the long string that switches in or out the printer effect as the translation. The 'OFF at CR' option within the printer driver affects only the printed output. It does not generate the same effect on screen. For example, if you change the printer driver so that italics are not turned off at <CR> and place one highlight at the beginning of the first line of your document then you will find only the line containing the highlight code is in italics on the screen but the printed output will all be italics. This is because PipeDream does not read the 'OFF at CR' column of the printer driver file before displaying on the screen. For maximum compatibility between what is shown on screen and what is printed I suggest that all highlights should be turned 'OFF at CR'. RISC OS Printer Drivers Having got the text onto the screen you then need a RISC OS Printer Driver for your printer. I have copies (for distribution to PipeLine subscribers) of Acorn's latest (Version 2) RISC OS printer drivers. Acorn have supplied some for 9 pin and 24 pin printers and one for the HP LaserJet. I use an Epson GQ-3500 in HP emulator mode but other PipeLine readers have sent me letters printed out using the RISC OS HP LaserJet driver with the much cheaper (but slower) DeskJet or with one of the 'Bubble' printers. Of course you can dump !Draw files to a DeskJet at high resolution with the Acorn RISC OS HP LaserJet driver. RISC OS printer drivers are those which, up to now, have been provided by Acorn and you use the RISC OS drivers with outline fonts. The old Acorn anti-aliased fonts (sometimes called 'Fancy Fonts') were bit mapped on screen and have now been replaced by a much superior method called 'Outline Fonts' in which every letter is stored as a picture which can be drawn with full resolution at any scale. If you are going to use the RISC OS drivers then I strongly recommend that you change over as soon as possible to the new outline fonts such as those on our DrawPlus disc. If you are going to 'stock up' with outline fonts then I suggest that you get a free catalogue (of well over a hundred fonts) from the Electronic Font Foundry (EFF). The Acorn fonts are all for the Latin 1 character set; EFF can supply other character sets as well. The address of EFF is: The Electronic Font Foundry Bridge House 18 Brockenhurst Road Ascot SL5 9DL The way that the RISC OS Printer Drivers work should not be confused with a screen dump. The characters that you see on screen are not bit mapped but are drawn from a set of lines. When you print these characters they are redrawn (in memory) at the full resolution of the printer and the bit map sent to the printer is at the resolution of the printer and not at the resolution of the screen. The picture of the letter which you see on the screen and which gets sent by the RISC OS Printer Driver to the printer are generated by the Acorn Font Manager and not by PipeDream. PipeDream integrates beautifully with Acorn's Outline Fonts and RISC OS Printer Drivers. Summary System font character sets are an 8 by 8 matrix of pixels (like a small sprite), outline fonts are drawn (like a small !Draw file). All characters are stored by PipeDream as a character code between 0 and 255 not as a sprite and not as a drawn picture. These character codes can be sent to a PipeDream Printer Driver (and, if you want, can be translated into other codes at the printer). If you are using outline fonts then you will see drawn pictures on screen. It is these drawn pictures which are sent to the RISC OS printer driver. %C%RISC OS Printing %C%by Gerald L Fitton Some of you have 'complained' that the printer driver !PrinterDM or !PrinterLJ chops off some of your picture. Although not strictly a PipeDream problem (it happens with Impression and other DTP programs including Acorn's !Draw) the solution has a place on this disc because of this use of PipeDream. Often the problem can be cured by carefully setting up the page size of the printer driver as follows: Measure your paper size and, if you are not using a standard size such as A4, change the paper size in the paper size sub menu. You may have to alter some dip switches inside your printer because, on some printers, the software commands do not override the dip switch settings for page length. One PipeLine reader bought his printer from a UK importer and, after getting unwanted form feeds at the end of every printed page, found the dip switches were still set to the American page length! Install the printer driver on the icon bar and then click the mouse menu (middle) button and run the pointer through select the Page size sub menu. Set the top and left margins to zero (0.00) - you can also set the right and bottom margins to zero at the same time. Now load the file called Rectangle (on this disc) into !Draw. Print this picture (you can use low resolution for speed) and then measure (as accurately as you can) the distance from the top of your paper to the top of the printed picture. Reselect the page size sub menu and make this distance your top margin. Measure the left margin and enter this in the page size sub menu in the same way. Print Rectangle again. Measure the distance from the right hand edge of what is printed to the right hand edge of your paper. This is your right margin. The bottom margin is a little more tricky but you set it the same way but increasing it a mm or two to give you a small reserve. With some printers the paper stretches or slips as it goes through the rollers so that the page length seen by the printer might not be the same as you measure with a rule! If you make the page length too long you will get unwanted form feeds; if you make it too short then your bottom margin will be a little more than the amount you measure from the bottom of the paper. Switch on the Misc - Paper limits - Show sub menu of !Draw and you will find that the shaded area of the !Draw screen is exactly the bit which is not printed. If your left and right margin differ greatly you may be able to move the printer feed mechanism to centre the paper in the printer.