Martin Russ offers an antidote to the hype of Windows 95 and explains why the future of computing lies with the PCI buss...
As I write this, September 1995 is being seriously over‑hyped by the media because of the launch of Windows 95, the latest version of Microsoft's graphical operating system for IBM PC‑compatible computers. Having used the full release version of Windows 95 for some time, I must congratulate Microsoft on a marvellous piece of software. It is intuitive, easy to use, first‑time friendly, has lots of shortcuts for experienced users, and gives a nice set of graphical metaphors for using a computer. It manages to turn a distinctly unfriendly DOS machine into something which is usable by almost anyone (yes, you are reading the Apple Notes column, honest!).
My only question is: why it has taken Microsoft so long to get to where Apple were many years ago? Windows 95 is huge, complex, and very user‑configurable, but it feels like they have thrown a Mac, UNIX and Windows 3.1 into a pot and merged them together without doing any pruning. There are still inconsistencies and awkward solutions in there, and although you can do just about anything, I can't help feeling that it still lacks the streamlined, polished gloss of my Mac's System 7.5 (and besides all that, Opcode's Max is still only available on Mac!).
How It Works: The PCI bus
You've probably heard about the PCI buss, although all the mentions that I've seen in computer magazines so far have been rather vague. Since any future Mac that you might buy is very likely to have a PCI slot in it, this seemed like a good time to look at what PCI really is. The best place to start any discussion on computer busses is to put them into context — after all, confusion is the one thing that is certain with any talk of buss standards.
You can't always believe in corporate images. You may have heard that the Peripheral Component Interconnect (PCI) buss was originally designed by Intel, and so you might imagine that there would be no way it would ever get anywhere near a Macintosh — but you'd be wrong. Although originally defined by Intel's Advanced Development Lab in early 1991, the responsibility for controlling and updating the buss was handed over to an independent committee, the PCI Local bus Special Interest Group (PCI SIG), in June 1992. Intel even made the PCI patents public domain — and so PCI is not a proprietary standard. As a result of this far‑sighted generosity, PCI looks set to become the unifying buss for all personal computers: IBM/Intel PC compatibles and Apple/Motorola PowerPC compatibles. Many workstations now have PCI slots too.
The main processor in a computer communicates directly with its RAM, ROM, and cache memory, using a host buss — the Processor Direct Slot (PDS) in a Mac provides this direct access to the processor. Any other busses in the computer hang onto this host buss using a bridge. In the past, computers have been designed with a bridge to a system buss (usually proprietary, and often very manufacturer‑specific) that forms the backbone of the computer. These are the ISA or EISA busses that you find in many IBM‑compatible PCs, the MCA in IBM PS/2s, and the NuBus in Apple Macintosh II, Quadra, Centris and the first Power Mac machines.
PCI changes this architecture by providing a single bridge between the host buss and the PCI buss. The PCI buss then acts as the primary buss for any other buss usage. A PCI‑to‑ISA bridge would provide an ISA buss in a PC‑compatible, whilst a PCI‑to‑NuBus bridge would give NuBus slots in a Mac. Secondary PCI busses can be hung onto a PCI buss by using a PCI‑to‑PCI bridge.
PCI busses are short, unterminated, designed to cope with multiple processor architectures, and support simultaneous activity from the processor, input, output, and memory. You may well be familiar with the idea of providing a termination for a buss from SCSI connection to Macs, where the last SCSI device needs to be terminated so that the current flows from the Mac to the end of the chain of SCSI devices. PCI's unterminated design means that signals deliberately reflect back along the buss, which is why the length is defined to be short: short enough that the maximum round‑trip delay for a signal must be less than 10 nanoseconds (that's 10 billionths of a second). This places severe demands on the design of the buss and the cards that plug into it.
Next time, I will look in more depth at computer buss performance.
On The Net
There's some fascinating discussion on Apple's World Wide Web site on the subject of Windows 95, including a competition (US only, unfortunately) for the best reasons 'why I still prefer my Mac...', and lots of other Windows 95‑orientated information. Here are some places to surf:
- www.apple.com
(for an alternative view of Windows 95); - www.microsoft.com
(for Windows 95 information); - www.claris.com
(there's rumours of a Beta tester of an E‑mail program somewhere); - www.kaleida.com
(OpenDoc information).
Tip Of The Month
One of the best ways of finding out how to make the most of your Macintosh is talking to other owners. For many years, a number of independent Apple‑user groups have provided a way for interested Mac users to meet, discuss, swap tips, and generally immerse themselves in Apple computers for the whole of a meeting. Although you are unlikely to find many other musical Mac users, you will probably meet graphic designers, Photoshop artists, DTP experts, and even the occasional database designer who can talk SQL like a native. Mac owners are often enthusiastic, even evangelistic at times, and I've always found Mac‑user group meetings to be useful, if not essential, events.
So how do you find out where your nearest Apple‑user group is? Perhaps the easiest way is to call the Apple Information Centre on 0800 127753 (notice that number? It's an 0800 number, which means that it is free!). When you call the number you will find it an invaluable resource of information on Apple‑related topics — like user groups, for example. I have always found them to be helpful and knowledgable, providing an invaluable resource of information. Please remember, this is not a free support line, so don't try asking them about technical problems you are having — for that, you need to subscribe to one of the many software or hardware support schemes.
Apple News In Brief
BARGAIN MACS
Just about now, you should find a number of PowerMac 7100s and 8100s appearing on the market. Variously described as refurbished and warehouse surplus, these are a combination of clearing stocks and the moving on of old Apple machines to make way for new models. Both models have NuBus slots and ought to be available at bargain prices — especially if PCI‑slotted replacements start filling the shelves. Contact your local Apple dealer for more information.
MAX POWER
The update to Max 3.0 arrived at the Apple Notes HQ recently, and I'll give you more details when I've had a chance to get to grips with its new features! For your update (only £399.95 inc VAT) contact Lars at MCM on 0171 258 3454.
IN CONFERENCE WITAPPLE
Apple continue to extend their operating system support into multimedia. After QuickTime Music, QuickDraw 3D, and QuickTime VR, we now have QuickTime Conferencing, designed to make desktop conferencing (document, audio and video conferencing) easy over LANs and the ISDN. It supports industry standards like H.320 (you might have seen the BT adverts for their H.320‑compatible videophone on TV and in the press recently) and T.120, and is designed to be independent of transport medium, compression devices and media, as well as offering support for open standards for interoperability. In a word — flexibility!