PowerPC & Custom Icons

Taking over the Apple Notes hot‑seat, Martin Russ delivers more news about PowerPC and explains how to create custom icons.

One of the first things that people ask me when I put one of my disks into their Macintosh is: 'How do you do that?' They don't mean how do I put the disk in, of course, they mean how do I get different disk and folder icons. Since the first few minutes of most sessions then consist of me showing them what to do, this seems like a good time to pass on the 'secrets' to a wider audience.

Any Macintosh with System 7 installed has the capability to have custom icons, and most of the tools that you need are supplied too, but the trick is knowing what to do to make the most of them. You can jump into the deep end with Apple's ResEdit resource editor, or even a commercial icon editor if you prefer, but why spend money that is much better invested in more RAM or a bigger hard disk?

To change the icons of disks or folders, you need two things: (1) a source of icons, and (2) somewhere to put them, ie. the destination. You can use almost any file, application, folder or disk drive as a source of icons. You will need to supply the disks or create the folders yourself, of course. Here's how to do it:

Creating Custom Icons

1. Prepare a new folder. Move to the folder where you want your new custom folder to go, and select the 'New Folder' option from the 'File' menu. You can also use the keyboard shortcut (Command‑N = the funny propellor symbol plus the 'N' key) if you prefer. To prepare a disk, you just need to make sure that it is on the Desktop.

2. Locate the source of the new icon. Click on it once to select it, and then use the 'Get Info' option from the 'File' menu to open an information box about it. You can use the Command‑I shortcut here to save time and reduce wear and tear on your mouse.

3. The top left‑hand corner of the opened information box shows the source icon. Click on it, once. A black square will appear around it. You can now use the 'Copy' option from the 'Edit' menu to put a copy of the icon into the clipboard. Shortcut users will probably use the Command‑C key combination here. You can now close the information box.

4. You now choose the destination for the new icon. Select the disk or folder that you want, by clicking on it once. Then use the 'Get Info' option again (from the 'File' menu) or use the Command‑I keyboard shortcut.

5. An information box will now appear for the destination disk or folder. In the top left‑hand corner will be the existing icon for the disk or folder. Click on it, once. The black square will appear around it, just as before. You can now paste the replacement icon by using the 'Paste' option from the 'Edit' menu. The Command‑V keyboard shortcut works just the same. The icon that you copied from the source should now be shown in the top left‑hand corner of the information box. Close this information box.

6. Don't panic when you look at your newly customised folder or disk and it has not changed! The Macintosh is still using the icon that it loaded when you first booted up your machine and it read the disk directory. The next time that you start or restart your Macintosh, the new icon will be there, just as expected.

Troubleshooting

Some things just never go right, so here are some pointers to fixing problems which you may encounter when trying to use custom icons.

• Don't be put off by all those instructions. It is actually very easy, and the benefits of having easy to understand icons on the Desktop makes it well worth the effort of learning what to do.
• You may find it hard to avoid clicking twice on some files, which causes them to launch the application program itself. Take your time and click just once, carefully.
• If no information box appears when you select 'Get Info', then this means you can't use that object as a source for icons — are you sure that you have selected a file, folder or disk icon? Almost anything on the Desktop is OK to use — even a full Wastebasket!
• If you have a very full hard disk, then you may not be able to add custom icons. But this is rare — 50 folders with custom icons only consume about 10k of RAM.
• You can change the icons used for files in exactly the same way — but then you can lose track of what program the file belongs to. It can also be very confusing if you re‑use application icons — because then you can't tell where the original application is.
• What if you don't like the new icon and want the original, boring, default back again? Simple. Just use 'Get Info' to reveal the information box, then select the icon and use the 'Clear' option in the 'Edit' menu. Shortcut users look like they are stuck at this point, because there's no obvious keyboard shortcut for 'Clear' — but there is an alternative — just 'Cut' the custom icon with Command‑X.
• So where do you get neat icons from? Almost any of the Mac Public Domain or Shareware suppliers (see ads in Mac magazines) should have folders full of alternative icons — and these days PD and shareware can be obtained via disks, Bulletin Boards or even CD‑ROMs. Since CD‑ROMs are becoming the rising stars of software distribution, it makes sense to mention one that I have used several icons from: BBS In A Box from the Arizona Macintosh User Group. Most Macintosh CD‑ROM retailers should be able to get hold of the current version for you (volume 10 is the latest, but older versions are often sold off at considerably cheaper prices) — but shop around, since I have seen prices varying considerably. As a bonus, you get lots of MIDI Files too, as well as hundreds of megabytes of almost anything else you can think of Mac software‑wise.

Powerpc

One of the most misunderstood things about the PowerPC chips that will power the 'next generation' of Macintoshes is compatibility. Ordinarily the acid test for compatibility of any piece of software is actually runnning it on the 'target' computer, but it will not be quite that simple with PowerPC‑based Macintoshes. As Kendall Wrightson explained in these pages last month, applications can run either under 'emulation' or as 'native' code.

NATIVE CODE means that the software is written specifically for the PowerPC processor, instead of the 680n0 that it currently uses. So the software company has to recompile the program and fix any problems — which could take some time. An Apple representative told us at Apple Expo 93 that ClarisWorks was 'ported' to the PowerPC in a day, with only a few lines requiring any changes. Cynical Mac music‑makers might do well to assume that the complex timing and hardware requirements of music software could involve a more time‑consuming process. With the major software companies already working on converting the big name programs to PowerPC, most of the problems will be sorted out, and so the job should be made much easier for the smaller music software companies. You may well find that future Macintosh software comes with two sets of data files: one set compiled for 680n0 and the other for PowerPC. The major advantage of code compiled for a specific processor is that it runs fast — the basic 601 PowerPC chip has about two or three times the processing power of the Quadra 950, and forthcoming 60n series chips will provide even more powerful processing.

EMULATION is a more interesting and potentially more complicated process. Rather than do anything to existing code, you make the PowerPC chip 'appear' to be a 680n0 chip. This is exactly what happens with the existing software 'PC emulators' for the Macintosh (eg. SoftPC) — they run code written for the PC's 80n86 processor by translating the instructions into 680n0 instructions. This is a complicated task, which explains why most emulators run very slowly. For example, to run 'Windows' on a Mac with a PC emulator you really need a fast Quadra to obtain acceptable speed. Even though the 601 PowerPC has more processing power than the top of the line 68040 chips, emulation would still mean an effective drop in performance — if it were not for the ingenuity of Apple's engineers, that is.

What Apple have done is very clever. Because Macintosh software spends most of its time executing instructions that are held in the Mac ToolBox ROM, then if you recompile the ToolBox routines so that they are 'native' to the PowerPC, then you can have emulation without the marked performance penalty that you might expect. In case you are sceptical about the effectiveness of this strategy, then bear in mind that access to just about any feature of the Macintosh is always via the ToolBox (which every Mac user simply takes for granted). Macintosh applications use ToolBox routines to open files, put graphics on the screen, interact with I/O ports and just about everything else — in fact, large chunks of most Mac programs are little more than just a list of calls to ToolBox routines inside larger controlling routines. For example, this pseudo‑PASCAL program segment shows ToolBox calls in non‑bold type, and they occupy almost half of the lines in this simple (and probably buggy) Dialog box handler.

So by reworking the ToolBox calls into PowerPC form, Apple claim that the 601 can emulate a 680LC40 processor at LC475 speeds. The slow emulation of non‑ToolBox 680n0 code is compensated for by the rapid running of recompiled ToolBox routines on the 601 processor. So if your code currently runs on a 68040 processor, you ought to achieve similar performance without any need for a new recompiled version. Apple claim that about 95% of the software they have tried will work using emulation.

Using emulation techniques on the PowerPC, the 'PC emulators' will also be able to offer performance equivalent to a 25MHz 486, which means that Windows on a Macintosh would be fast enough to be usable — but beware of assuming that this means that you can run timing‑critical and I/O port specific music software.