Last changed 11 Feb 1998 ............... Length about 1,000 words (6,000 bytes).
This is a WWW document by Steve Draper, installed at You may copy it. How to refer to it.

Acrobat readers

A new web document format is becoming widespread, known as PDF format. To read these documents, you need a free Acrobat reader from Adobe, unless your machine already has one. Student cluster machines at Glasgow university do now have one as standard.

To get one, download one from Adobe.

Or you if you want a version 3 one for the Macintosh from this site, ftp here.

PDF format & Acrobat readers: Is it a good idea?

PDF is a new document format, becoming widely used in conjunction with the WWW. The format is related to postscript, but uses all 8 bits plus compression. It is promoted by Adobe. You can get a free viewer software from them, so everyone can fairly easily read PDF documents. They hope to make money from authoring software. However you can get free software to create PDF from postscript.

PDF files often look bleary, blurry, smeary on screen. I don't know why, but probably to do with the fonts specified in the original document and not done well by the viewer.

Main features of PDF

This means that if you want to distribute a printed document via the web, for users to print locally but also with an option of viewing it on-line, then PDF is a convenient route for many although not all people. But if the document is meant primarily for viewing on the web, then there are objections:

Why it is bad for primary web pages

So what is it good for?

Use at University of Glasgow

The university has adopted it as a standard facility, so PDF viewers will be on the cluster machines undergraduates use: you can rely on this. Furthermore those clusters do not have a facility for printing postscript files, so you can't distribute documents that way.

It is probably not a good idea to use it as an alternative to handouts: it will just cost more and block up public equipment if all your students are going to want or need a paper copy.

It probably is a good way to put reminder copies of OHPs etc. on the web at little effort to yourself.

It probably is not a good way to author web pages.

How to create PDF documents for the web

These instructions will work, at least for Mac users.

Getting PDF creation software

You can buy Adobe's software: Adobe's web site

Aladdin Ghostscript software is great, free at least to academics, and available on the net. It is both a postscript viewer AND PDF conversion.
However, I have recently found it does VERY badly at converting postscript files with any graphics at all in. Selecting options in the print dialogue used to create the postscript file to force downloading of all fonts used helps a bit, but does not solve the graphics problem.

Aladdin Ghostscript: Mac users begin here
Aladdin Ghostscript: Others could begin here.

Demo PDF document

File sizes / download times

PDF uses 8 bits (not 7 bit ascii like postscript) and file compression, which can reduce download time. This seems to make it competitive with HTML, and certainly much better than postscript files for size and hence download times. Here is a table concerning a test text file.

File type
File size (bytes)
File size (Relative)
Ascii text