07/03/95 Questions and Answers --------------------- I want to connect to the Internet; what do I do? First, you need a communication line in to the Internet itself. A number of companies around the UK have set themselves up as "service providers;" that is, they have purchased a high-bandwidth Internet feed and the commodity they sell is the facility for subscribers to connect into their feed. The means of connecting is usually by a modem and dial-up telephone line (see later for details of modems), although if you have a large installed base of machines at your site which you wish to connect, and you will be making use of many sevices which consume high bandwidth (such as World Wide Web), service providers may suggest ISDN or a leased line as a higher-speed alternative connection mechanism. Finally, you need communications software which is capable of supporting a TCP/IP stack, and if you are using a dial-up link, either SLIP or PPP; these protocols put headers and footers around the IP frames to render them suitable for sending down a serial link. If you wish to use more advanced facilities than just email and remote login capability, you will need software which handles the specific protocols for such services and which sit on top of TCP/IP; nntp for USENET newsgroup access, http for the full facility of World Wide Web, etc. Modems in All Shapes and Sizes ------------------------------ If you are considering buying a modem, you will run into lots of specifications of the form V.nn, where nn is a two-digit number. These specifications refer to data communication speeds and occasionally data compression methods; details on the most common numbers appear below: V.27 Specifies 4800 bps communications requiring 2 wires for half duplex and 4 wires for full duplex operation. The standards specify QAM modulation at 1600 baud. The Group 3 Fax standard references V.27 ter as the base requirement for 2-wire half duplex fax communications. V.32 CCITT standard for 9600 bps full duplex modems. Specifies 2-wire full duplex 9600 bps communications using QAM modulation at 2400 baud and echo cancellation. V.32 modems offer an upgrade path from V.22 bis for asynchronous dial-up modem applications. V.32 AUTOMODE was recently published as an annex to V.32, and defines an automatic fall-back capability which does not support 9600 bps communications. V.34 The current state of the art in serial communications over the telephone, V.34 specifies full duplex 28800 bps. V.42 Specifies error correction techniques which can be implemented in modems independently of transmission speed and modulation system. This includes LAPM (Link Access Procedures for Modems) and MNP (Microcom Networking Protocol) 2 to 4 error correction. V.42 bis This specifies compression algorithms which can be implemented in modems independently of transmission speed and modulation system. V.42 bis provides a 4:1 compression ratio, using the Lempel-Ziv algorithm. When is C++ Not C++? -------------------- When it's CFront front-ending onto a C compiler. CFront, included in Acorn Desktop C Release 5, is a tried, tested and established translation engine which takes C++ source code and translates class objects etc at source level into the appropriate structure and redirection paradigms in C. The C which results does not comply with any models of programming style, but it is nonetheless compliant with the ANSI C standard. Enhanced Font Handling in RISC OS 3.5 ------------------------------------- One of the most obvious changes in the appearance of the Desktop between RISC OS 3.1 and RISC OS 3.5 is the use of outline fonts on the icon bar, in filer windows and in application menus. As well as by using the Configure application in the RISC OS 3.5 Boot hierarchy, the Desktop font can be changed using *CONFIGURE DESKFONT once the relevant !Fonts directory has been "seen" by the filer. Implementing outlined, kerned fonts on the icon bar and especially in menus is an interesting task for the programmer who chooses to build his interface manually (instead of using a tool such as !ResEd, included with Desktop C Release 5); use of !ResEd for this kind of task is recommended. SWI"Wimp_TextOp" detailed in Volume 5 of the RISC OS 3 Programmer's Reference Manual can calibrate the widths of text-containing menus to accommodate font changes, and for each line of a menu the text following the final space can be right-aligned.