13.5. PC Fonts   

The IBM PC machine is supported by Operating Systems such as MS-DOS, Windows (which run on top of DOS), OS/2, Linux, and Dr DOS. Hence, each Operating Systems has their own native font formats or font format that are commonly used.

Here are some fonts types that are used in IBM PC

TrueType

It is used mainly in Microsoft Windows 3.0 and above. Unlike Bitmapped Fonts the font information is not stored in a pattern. It is stored as a mathematical description of what the character will look like, at any size. What is actually stored is a series of points that describe a curve (the character). Some of these points will be on the curve and some will be off the curve.
The on curve points define the end points of a curve or a straight line and the off curve points influence the bending of the curve.
If there are two points in sequence that are both on the curve, the result is a straight line.
It is by adjusting the position of these points that we can scale the character to any size, rotate it, skew it, stretch it, invert it or otherwise modify it fairly easily.
The way the Macintosh achieves this task is described in Inside Macintosh (p 12-13)
The Font Manager fits the outline glyph [character] scaled for the correct size to this grid. If the centre of one section of this grid - comparable to a pixel or a printer dot - falls on a contour or within two contours, the Font Manager sets this bit for the bitmap.
This means that if you are mapping a large character, say 100 point (100/72 of an inch) onto a high resolution, such as a 300dpi printer, the number of dots would be huge, and any jagged lined would go unnoticed. Scaling a bitmap up to a similar size would produce a very unpleasant jagged edge. A True Type font has the suffix .ttf

PostScript Type 1

PostScript Type 1 is used in OS/2 operating systems and Microsoft Windows 3.0 and above. It is the most common type of PostScript used in IBM PC and clones.

Bitmap

Bitmap fonts are used by Microsft Windows and OS/2. It has some limitations as mentioned previously.

Plotter fonts

These are fonts specifically designed to be printed on plotters. They are typically made up of lines and curves, very basic in shape and can be scaled in any size.

Printer Fonts

These fonts are hardwired into the printer's ROM and therefore can not be displayed on the screen. It is possible to print them, even though you can't get an accurate representation on the screen. The computer gives the instruction to the printer to print in it's native font. Since displaying the font is impossible, Windows substitutes a screen font to represent the printer font on the screen. Sometimes (more often than not today) a printer driver disk may include screen fonts that are an exact replica of the built in printer fonts. This is so the user has a clearer idea of what the finished document will look like, while it is still on the screen.

EGA/VGA text-mode fonts

These fonts are used in MS-DOS screen fonts These are a kind of bitmapped font used by Windows to display information on the screen. These are the fonts used in Menus dialog boxes, message boxes and are not intended for printing. Each screen font may come in a number of sizes. Although not intended for printing, they can be printed, but with poor quality

Since Windows aspires to a universal interface, it primarily supports the ANSI standard. Fonts based on the ANSI characters are called ANSI fonts. In Windows version 3.1, Microsoft has begun to refer to its version of ANSI as the Windows character set. If your computer has a different character set built in, Windows calls an Original Equipment Manufacturer (OEM) font. Windows includes the OEM font primarily to accommodate non-Windows applications.

For Windows, the font types available are raster, vector and TrueType. Raster fonts are based on bitmaps, they can be designed more easily and displayed more quickly. It is also very easy and quick to resize them. Unfortunately they are not rotatable, and they become more and more blockier as they are enlarged. On the other hand vector fonts can be rotated and scaled to any size. Besides that, the lines that form a vector character remain clear at any length.

TrueType is another way of defining fonts for digital processing. Fonts defined in other common professional formats, such as Ikarus or PostScript, can be converted to TrueType fonts. TrueType is already in use on the Macintosh, in fact the Windows of this standard greatly increases the portability of formatted documents between machines. Fonts designed for one system may not contain all the characters common for the other machine, but in general the fonts transfer with only minimal adjustments to the data file. Furthermore, the 13 core TrueType fonts that come with Windows closely match the design widths of the core PostScript and Macintosh System 6.0.5 fonts. Microsoft has made available a lengthy document called TrueType Font Files Specifications that explains how to create a single font file for Windows, Macintosh and TrueImage.

With TrueType fonts, Windows can now do several things that it could never be done before. It can match screen and printer fonts exactly. It can also draw clean text scaled to any size with reasonable speed. The new and more detailed font metrics available for TrueType fonts make it possible for programs to generate documents that will not "reflow," or change line and page breaks, when moved from one printer to another. To do this, applications need to design a logical document at some imaginary high resolution, notice when a printer requires adjustments to the line width, and compensate for the difference by adjusting white space on the line. Finally, TrueType fonts can also be embedded in documents so that any necessary typeface will accompany the document from system to system.