This article was originally written by Simon N Goodwin for Amiga Format magazine, and is used by permission of the joint copyright holders. It should not be copied any further without written permission. OCTOBER 2005 UPDATE - a seven page review of two leading Mac emulators, ShapeShifter and Fusion, from a later issue of Amiga Format, has now been uploaded to this site in PDF format (see the updated links, at the end of this web page). The free emulators mentioned were included on the accompanying CD with the magazine, and are generally available - often in updated form - from Aminet. The text is as originally submitted to the magazine - which means there are some differences, mostly extra text which was cut to fit into the pages available - with the addition of hyperlinks to new or updated information which has since become available. This approach has been taken to preserve the structure of the original series, while making new information readily available. Simon welcomes comments from readers, via the email address on the index page.

Apple Mac emulation

In the mid eighties two new micros took radical steps away from the command -dominated mainstream of CP/M and MSDOS. Macintosh and Amiga computers have grown and converged since, but they still represent unique, brilliant and enduring ways to make a computer useful.

Expanded Amigas can emulate Macs with ease, while Macs - like anything else - struggle to emulate even vintage Amigas. A fine shareware emulator, ShapeShifter, is freely available and can be registered for $40. The new commercial Fusion emulator supplants Emplant Lite, while older hardware emulators Emplant and AMax still have a following.

Why Mac?

Macs are easy to use and there's lots of good - if pricey - software for them around. Old versions are bargains, as you don't need recently-added PPC code anyway. Macs run global champions like Excel, NetScape, PhotoShop, Quark Xpress and Word. Games include Doom and Duke Nukem, unavailable on Amigas lacking Mac emulation.

They're based on Motorola processors, as are Amigas, so programs run at full speed, unlike PC emulators which are crippled by the need to translate every instruction as they run. Macs and Amigas are both good, and very different. So if you can have an Amiga AND a Mac - why not?!

The fastest Amiga graphics boards and processors outperform 68K-based Macs, and PowerMac emulation is in the works for putative PowerAmigas. The Amiga system remains useable, while Mac emulation runs alongside, on separate screens or in windows.

ROMs

Emplant demanded a 256K ROM image, keeping things simple for the emulator patches but making it obsolescent - 256K Mac ROM sets are rare in the 1990s, and unsupported since System 7.6. Fusion and ShapeShifter handle ROM sizes from 256K up. Most 68030 systems have 512K ROMs, with megabyte ROMs supporting the copyback cache in the fastest 68K Macs. 2 Mb PowerBook and PowerMac PPC ROMs are useless on current Amigas.

AMax and Emplant ROM sockets let you plug chips from a real Mac into your Amiga, and copy the code to an Amiga file. ShapeShifter introduced a different approach, later followed by Fusion. You need access to a working Mac, but don't need to take it apart to extract the chips.

A Mac program, supplied, copies the system ROM contents to disk, for transfer to the Amiga. The transfer each way must use PC format disks, as they can be read and written on both machines, with FileExchange on the Mac and MessyDOS or CrossDOS on the Amiga. Fusion 1 was incompatible with some of the claimed 143 Mac ROM variants; version 2 is more tolerant, but still not perfect and - typically - lacks any list of what will and will not work.

Mac Systems

Like the Amiga, the Mac has a healthy proportion of its system code ready to run in pre-programed ROM (Read Only Memory) chips. This must be available to the Amiga - with due deference to copyright laws - before the emulators will run. You also need the Mac system files, normally supplied by Apple on CD or HD floppy, which are the equivalent of Amiga Workbench disks - but more so.

Most modern Macs and emulators run 32 bit system files, known as version 7. The original 7.0 release works with ShapeShifter but not Fusion, which requires at least version 7.1 and prefers 7.5 or 7.6 - intermediate versions were not released. A third digit signifies minor changes, e.g. 7.5.3. Later versions mainly gain Power PC code. The new release 8.0 occupies almost 300 Mb of CD space; it runs on Fusion but not ShapeShifter, and has some problems with 68060 processors, which Apple skipped in favour of Power PCs.

AMax, designed for 16 bit systems, runs Versions 4 to 6, all limited to 24 bit addressing like the A1000, A500 and Zorro 2 Amigas. Emplant and Amax Zorro boards can run system 6 or system 7, and Fusion can emulate 24 bit addressing with the MMU, to placate buggy old programs.

Hardware

Apple Macs have serial ports, SCSI, optional Ethernet, and their own low -cost network called AppleTalk. Apple connectors are often peculiar and hard to find. Floppy drives were originally non-standard, in 400K and 800K capacities with variable-speed 'zone' recording which made most of the data inaccessible to standard 300 RPM Amiga DD drives. Later models have 1.44 Mb superdrives, compatible with normal HD floppies but also capable of accessing the weird old format, and double (720K) or high density PC floppies.

Macs are peculiar in many ways. There's only one mouse button, no command line, and you must explicitly 'shut down' your system to avoid loss of data. Disks should not be ejected unless you've moved them into the 'trashcan' first. Real Mac drives enforce this rule mechanically; on an Amiga you break this rules at your peril.

Fusion and ShapeShifter allow Mac devices to be mounted and used as Amiga drives while the emulation is running. You can also cut and paste text - but not graphics - directly between systems. Printing may be tricky as Mac system software only supports Apple's proprietary printers. There are free third party drivers for Epson and Deskjet printers, and commercial rivals. You can use 'desktop printing' to generate postscript files to print from the Amiga with Post or GhostScript.

SoftFPU - on our CD - emulates a 68882 chip so programs using FPU code will work on machines without floating point hardware - albeit much slower than they were designed to run. Mac software is far hungrier for resources than Amiga equivalents - you can run a useful Amiga system in 6 Mb RAM with a 40 Mb hard drive, but a Mac with that specification would barely start up.

ShapeShifter supports most Ethernet adapters, and Fusion works with the Hydra Systems card, but not our Ariadne boards. SCSI ZIP drives or CD-R discs are perhaps the ideal way to transfer data, but floppies and serial links are also possible. AF 102 documented the standard Amiga and Mac serial connections. As usual, add-on hardware boosts your options.

AMax

Amax boards fit a Zorro slot or Amiga floppy port, with sockets for Mac system ROMs. The original model had an interface for a non-standard 800K Mac drive (recently offered for a fiver each at a local radio rally) - one simple TTL chip, with three more to get around the bizarre installation of 16 bit ROMs in a serial disk socket. Amax II+ and Amax 4 (for Zorro) add more ports and can read old Mac disks in a standard Amiga drive.

Emplant

The 'basic' Emplant is a mostly empty board with timer and interface chips and DIP and SIMM sockets for Mac ROMs. It can be extended to 'deluxe specification' with a Mac-style SCSI-1 controller, Appletalk network interface and a change of the copyyright-control PAL (Programmed Logic Array). Emplant software requires this board - Fusion uses it, if present.

Catweasel

Fusion can accesss Mac disks via the Catweasel controller, much faster than custom Amiga HD drives and supporting cheap PC-type drives. Catweasel itself lacks Workbench support for Mac disks, but works well alongside Fusion and ShapeShifter 3.7 or later.

Video Modes

As regular readers will recall, the Amiga has its own way of doing graphics. Other colour computers pack the bits for each pixel together, but Amigas store them in planes scattered around chip memory. This was a neat solution in 1985 - the Amiga was far more colourful than its rivals. To paraphrase Henry Ford, the Apple Mac was available in two colours only - black and white.

Amigas still work well if you're short of memory and only want a few colours on each line of the display, or your software knows about specialities like HAM modes (4K or 256K colours), but they're hassle for emulators because 'chunky pixel' operations that take just one step on alien hardware require six or eight, and often some tricky arithmetic, on ECS or AGA Amiga graphics.

This bottleneck encouraged plug-in video cards which store displays as Mac, PC and Unix systems expect. Old cards offer more colours than contemporary Amiga hardware, and new models are faster in all modes. These require an Amiga with Zorro slots, and preferably a video expansion slot too, and they're not cheap either.

ShapeShifter has a well-defined interface for display add-ons, called EVDs (Extended Video Drivers) so custom support is freely available for most graphics cards and Amiga chip sets. It makes direct access to Amiga bitplanes, Grafitti, Merlin, Picasso 2 and Retina Z3 boards, as well as CyberGraphX, EGS and Picasso96 retarge table graphics (RTG) schemes. Features vary so it's worth trying all the possibilities, including third-party drivers, to get the best match for your system and software.

The original Amiga Mac emulator AMax stuck to mono Amiga graphics. Its rival Emplant added custom drivers for A2410, AGA, Cybervision, CyberGraphX, ECS and EGS, Merlin, OpalVision, Picasso 2, Piccolo, Retina, Spectrum and other esotechnica, but struggled to keep up with new arrivals.

Fusion takes a more selective approach. The only cards specially served are Retina Z2 and Z3. Others are driven via Picasso96 or CyberGraphX RTG libraries, discussed in AF101. Only version 3 of CyberGraphX works properly. You're best off using Picasso96 on a Z3 Retina, as long as you'e got a modern Workbench - the custom Retina driver is less capable, but it's Fusion's only non-Amiga native driver compatible with Kickstart 2.

Grafitti

Lateral thinking inspired German hackers to develop Grafitti, a plug-on which reads the digital signals from any Amiga video port and re -scrambles them so that 'chunky' display data can be stored in Amiga bitplanes. Display output software pretends it's got a chunky display map, ideal for Doom-style 3D, Mac and PC emulation; the hardware does the rest. This works but has limitations.

Firstly, the data is not in standard chunky format. Bits for each pixel are stored together but pixels are scattered between planes, so some software sleight of hand is still required, although much less than with a standard planar display. Secondly it's still using Amiga chip memory, which gives custom chips four to eight times the priority of the processor, slowing updates. It's not that Amiga graphics memory is slow, per se, but processor access is low on its pecking order. This handicaps emulators - but try to do a dual playfield (overlaid) display on a PC or Mac before you dismiss the Amiga scheme - it's horses for courses!

The 23 pin Amiga video connector's digital outputs for ancient RGBI TTL monitors supply just four bits at a time. 256 colour screens use eight bits per pixel, so Grafitti's resolution is half that of the equivalent Amiga mode. Grafitti offers 256 colours per screen, chosen from an eighteen bit pallete of 256K colours - more choices than with ECS but less than AGA.

Old Amigas bottle out at 720 pixels per line, stalling Grafitti at 360 column an 16 bit Amigas. This is too few for Mac emulation. AGA 'SuperHires' modes have twice as many pixels, but after Grafitti has finished you still only get 'HiRes' 640 to 720 pixel horizontal resolution, and no more than 283 lines unless you can stand a flickery interlaced display. you must use a 15 KHz video-compatible display, but composite monitors are not supported.

The real advantage is for the software driver, and both Fusion and ShapeShifter come with Grafitti drivers which are much faster than software which translates displays into planar format on the fly. Grafitti is a neat hack, but if you've got the internal slot, but any real graphics card will outperform it.

Akiko

Fusion has two display modes just for CD32 owners! These use the Akiko chip, a sort of internal Graffiti without the resolution limits, which converts pixeis from chunky to planar format in clumps of 32. Add-on ShapeShifter drivers can also use Akiko if it's there, benefitting committed CD32 owners with keyboard, hard disk and floppy add-ons.

QuickDraw

One major claim for Fusion is the toption to replace Apple's QuickDraw routines with code optimised for your display. Thus system friendly Mac programs - which means most of them - can take advantage of Amiga optimisations and hardware assistance like blitters, on the motherboard or graphics cards, without the need for graphics to be rendered Mac fashion into a 'pretend' screen area and then periodically translated into Amiga form.

Benchmarks make the most of this advantage, rating Fusion far beyond ShapeShifter in QuickDraw graphics speed. With real programs the benefit is more modest, and there's a risk that shortcuts introduce new bugs.

Refreshment

Some programs write directly to the Mac hardware, bypassing the system - an approach frowned upon by manufacturers but loved by hackers for its speed and simplicity. Jim Drew's QuickDraw boosters are sidestepped, leaving blank areas unless the entire display is periodically updated the hard way, dot by dot, to catch direct writes to the 'Mac' display which might not otherwise reach the Amiga. You configure the 'refresh rate' at which the whole screen is redrawn. High values - more than about ten updates per second - give better animation but can sap most of the processor power, even on a fast Amiga.

Memory Management

Salvation comes from clever, manufacturer-discouraged direct programming of the Memory Management Unit in superior Motorola processors. The MMU intercepts the processor's access to memory. It can shuffle a million 4K 'pages', monitor reads and writes and control processor caches, page-by-page.

Optimal refresh schemes use the MMU to detect modified parts of the screen memory, avoiding the need to refresh others. This is faster and less RAM -intensive than the alternative of 'delta buffering', comparing the old raw data with updates in an attempt to save redundant conversions.

MMU divination

Cheap Motorola processors - the original 68000, stock A1200s' 68EC020 and the 68EC030 in the A4000/030 and bargain accelerators - lack memory management. The 68040 and 68060 are available in bargain EC versions without memory management ($75 for a 50 MHz 68EC060!) but these are not yet used in Amigas, although they will work - I've tried them.

There's no official way for programmers to detect the presence or absence of an MMU, short of setting up several kilobytes of control tables and seeing if they make any difference, but that's only a real problem on the 68EC030s. Nonetheless, Mac emulators expect you to know whether or not your machine has a working MMU, to select an appropriate driver. MMU programming is a black art, forbidden by Commodore, and if you're not sure whether your MMU works the only way to find out is to try it - with a risk of crashing your system - or examine the entrails of your Amiga, looking for the not-so -magic letters 'EC'.

All A3000s and A4000s other than 4000/030s boast hardware memory management. 50 MHz 030 accelerators should all have MMUs, as the cheaper EC part is only available in lower speeds. 68020s require an external MMU chip, the rather obscure 68851; the original 68000 cannot support conventional memory management due to design oversights. The other possibility is a 68010 with a 16 bit 68451 MMU, but I've never seen that in any Amiga.

Amiga Modes

The simplest Amiga screen mode - a lone bitplane - works like the original monochrome Mac display, except that Mac pixels are always square and Amiga pixels are usually oblong. When colour Macs arrived a few years later they opted for packed screen modes, storing two16 colour pixels or one 256 colour pixel in each byte.

ECS Amigas can emulate 16 colour modes, but bitplane conversion makes them irritatingly slow. 32 bit AGA Amigas can manage 256 colours, but again this is slothful unless memory management is used to minimise processor overheads.

ShapeShifter's AGAboost does not require an MMU, but prefers a 68030 and uses a big delta bufer and a half megabyte table for conversions, laboriously rewritten at every palette change. AGAboost supports obscure AGA modes like Euro36 and Super72. It can speed things up by 'dithering' 256 colour displays into less demanding 64 colour modes. Despite the name, AGAboost can render 256 colour Mac software on ECS machines in 64 colour 'extra half bright' mode, although palette restrictions become obvious.

Thousands and Millions

When 256 colours is not enough, even choosing them from a much wider palette, Macs take a different approach. 'High colour' and 'true colour' modes use five and eight bits respectively to determine the red, green and blue level of each pixel, giving 32 thousand or 16 million colours. Humans can't distinguish all the brighter variants yet some darker colours are not available, because our eyes are not linear like a computer display, but 'true colour' seems pretty close to reality.

AGA Amigas support 16 million colours, but not all at once. There's never enough pixels! HAM8 comes closest, with 64 basic colours and the option to fine tune subsequent dots to an exact 24 bit hue. AmiRefresh modes in Fusion emulate thousands and millions of colours on an AGA HAM8 screen. It works, impressively, but it's slow.

Third party EVDs abound for ShapeShifter. AGA-EVD is aimed at basic 020 or 030 systems. It works accurately in 2, 4 or 8 pixel modes, and rather vaguely and slowly in HAM8, emulating the Mac 'thousands' setting. It can render four and 16 colour displays on ECS Amigas, but still requires Workbench 3.

ShapeShifter's Savage driver, from Hungary, supports 16 colours on all Amigas with an MMU, and 256 and 32768 colours with AGA. It outruns AGAboost and AGA-EVD, typically needing less RAM and CPU time, but requires a full -spec 68030. FastECS comes in 68030 and 68040 versions, using memory management to update 16 colour ShapeShifter displays on Amigas with 16 bit ECS graphics.

The venerable megapixel A2410 monitor is supported by Fusion through RTG, and a ShapeShifter EVD for the old EGS package.

Big Desks

A Mac speciality is support for multiple monitors. You can position these to view a 'virtual desktop' so the pointer, icons andwindows can be moved from one screen to the next, with all displayed at once. This is great for Computer Aided Design and Desktop Publishing, with tools and menus on one screen and the design uncluttered on another. ShapeShifter supports up to two displays, while Fusion can handle six, given enough outputs and monitors.

Graphics cards present some problems. Picasso 2 and CyberGraphX drivers can't detect screen swaps, so Mac and Amiga grapjhics sometimes appear on the wrong page when you swap screens, requiring a manual redraw to tidy up the mess. Picasso 2(+) and EGS system cards like GVP's Spectrum support only 256 colours without conversion. CyberVision 64 and Picasso 96 don't require conversion in 15 bit (thousands) and 24 bit (millions) colour modes, making them much faster.

Retina, CyberGraphX and Picasso 96 support in Fusion consumes an extra 4 Mb of fast RAM. This is a hefty extra burden - don't expect much change from 30 Mb if you need to run NetScape and Mac System 8.

Hit the Buffers

Emulated drives can appear to the Amiga as partitions or HardFiles. These are slower than dedicated partitions, but much easier to copy, backup and move because the Amiga regards them as large but otherwise normal files.

Access lags because the system cannot move directly to a given block. It must read the file sequentially to get to any position, because the blocks could be scrambled or 'fragmented' across the disk. The larger the HardFile, the longer this takes.

The 'cure' is to dedicate a partition, or add buffers. The standard block size is 512 bytes, when one block in every 73 contains a 'map' recording the location of that part of the file. This map must be re-read unless there's a spare 'buffer' to hold it in memory, so you normally need about one buffer per 36K for fast access to a large file, and over 1000 buffers (512K) for a 40 Mb 'hard drive'.

Fast File System 3.1 (v40.1 or later) lets you use bigger blocks. This can make a terrific difference. First back up the partition, as changing the block size zaps the original contents. Then run HDToolbox (in sys:tools), selecting a drive and partition. Choose 'advanced options' then 'change...' to see the file system characteristics, and choose bigger blocks; values from 1K to 32K are allowed. Select OK, adjust the preset number of Buffers (bottom left) and OK again to exit.

You don't necessarily need Kickstart 3.1, as the file system Add/Update option lets you put a later version, overriding ROM code, in the startup area of your drive. Amiga International's web site has an 'experimental' v43 fast file system, supporting bigger blocks, enormous drives, and ATAPI CDs.

The table shows how this works in practice, with boot times in seconds for a given block size and buffer count. The test system used ShapeShifter 3.1, Mac OS 7.0, a 50 Mb hard file and an 800 by 600 chunk CyberGraphX display; PCX, Fusion and PC Task deliver very similar results.

Doubling the block size quadruples the space each buffer can control (twice as many blocks, each twice as big) and boosts transfer speed as the disk interface takes bigger gulps. There's a 'right number' of buffers for a given size of file. An extra 90 half K buffers don't help at all,while 120 two K buffers are enough for hard files over 100 Mb long!

Tiny files waste some disk space as they always occupy a whole number of blocks, and tired old programs like AmiBack may be confused, but the RAM versus time trade-off is massively improved. 60K or 240K deliver ten times the speed if you use 2K blocks instead of four times as many half K buffers.

	1/2K blocks		2K blocks
Buffers	RAM used	Boot time	RAM used	Boot time
30	15K	324	60K	26
120	60K	324	240K	18
480	240K	182	960K	17
1920	960K	26	3840K	17

Mac file formats

Mac Files are divided into forks - rather than keep separate icon and program files, as on the Amiga, most files have a 'data fork' and 'resource fork'. Resource forks contain code, tooltypes, locale information and pointers to applications that created the data.

This split gives all Mac programs easily-customised windows, keys, graphics and text without affecting the underlying code. A wonderful tool, ResEdit, lets you hack up a custom system, so - contrary to prejudice - strait-laced Macs can be customised, although less than Amiga or Unix systems.

Handlers on the Amiga generally distinuish between forks by adding a prefix or suffix to the name. Macs support longer file names than Amigas, but this is rarely a problem. You can rename any file on a Mac by pointing under the icon, double-clicking, and editing the name.

Common archive formats for Mac files are .SIT - short for StuffIT, a shareware compressor - and .HQX. The latter files are expanded, rather than compressed, so binary data can be represented just with printable characters - rather like MIME or UUencoded files on Unix and Amiga. MacBinary is similar but shorter, using all eight bits without error checking.

LHA is available for Macs, and on our CD, but little used except to transfer files from an Amiga. ZIP is also supported, but uncommon, and sadly LZX is unknown to Macs.

Modern Apple applications are bloated by the inclusion of code for Power PCs as well as 68K Macs. Such 'fat binary' files contain both programs, and can be stripped to a fraction of their size if you know the bloated Power PC code is not required.

Documentation

Both Fusion and ShapeShifter come with documentation in AmigaGuide form. Emplant had a printed manual, but Fusion has nothing but the inlay to get you started. ShapeShifter's manual is longer and more helpful than the Fusion one, but even that's an improvement on Drew's previous efforts, which tended to assume you had a working system, with scant help with set -up or diagnostics.

The Fusion guide includes a glossary for anyone still clueless about terms like 'icon', 'Mac' and 'hard drive' and troubleshooting answers to fifty questions, but it has no index and is utterly inadequate for a commercial product, expecially one that stops dead or crashes if not set up just right!

The Emplant manual was worse, but the product was simpler and at least it came printed on paper. It helps to convert Fusion's guide with a utility like Guide2Text, printing it out to ensure you've not missed anything. Ironically the best Amiga Mac emulator manual by far is that for AMax - well written and printed, with a seven page index and lots of practical advice.

Macs are easy to use, even by Amiga standards, but if you want to tweak the configuration you'll probably need help from a Mac guide, human or printed. The emulator documents make no attempt to introduce the Mac system or file organisation, but most of it is self-evident if you've used Amiga OS or PC Windows, which owe much to ideas pioneered on the Mac.

AppleGuide tries to replace printed documentation with hypertext, and fails for want of structure, detail and ease of use. Multitasking is feeble by Amiga standards. Bubble help, as in MUI, tells you the purpose of buttons your mouse pointer lingers nearby. Error messages are rare but typically useless - if a Mac program needs to issue a message, it's a design failure!

Cold Fusion?

Simon N Goodwin puts Fusion head to head with ShapeShifter,
and awaits the release of energy...

Jim Drew's long-awaited third Macintosh emulator has arrived, in a marketplace now dominated by the shareware ShapeShifter. Fusion follows Emplant, which required Zorro 2, and Emplant Lite, magically remixed to remove the need for the formerly 'essential' dongle. It's pure software: one 880K floppy in a CD box.

Fusion has suffered from compatibility problems, inevitable when you consider the low-level way it meshes into both the Amiga and Mac systems. Version 1.0 was not submitted for review and we were unable to get much past the 'happy Mac' startup image on version 1.1, despite trying four different Mac ROMs, from 256K to 1 Mb in size. This left us in the odd position of waiting for version 2 before reviewing a product.

This is the most complicated, bloody-minded program I've reviewed in 18 years. With help from Nick and Ben I've spent over a month trying Fusion 2.0 on 68030, 68040s and A2/3/4000/060s, with Warp Engine and A4091 SCSI drives, ATAPI and ZIP drives, Catweasel, Buddha, Commodore IDE and HD floppies.

Each configuration required careful experiment, with changes of Mac ROM or CPU forcing reinstallation. The number of resets - forced and spontaneous - must number in the hundreds. But I persevered because, when it works, Fusion is brilliant, as you can see from the features discussed elsewhere.

Problems stem from poor documentation, bugs and Apple's restrictive practices. Fusion won't work with abundant, ready-made ShapeShifter boot files or the 'system disks' tailor made for each Mac model. You need a 'generic' system installation for any Mac, or the emulator gets stuck or crashes.

With NoiseSome in your WBstartup Fusion's audio code gets stuck, leaving RAM allocated with no message and reset the only way out. Abundant configuration options are overlaid, rather than in ShapeShifter's separate windows, and must be selected in the right order or they're ignored.

Once started, weird system-dependent errors occur unless you tweak the setup. Some Mac extensions cause problems, and lock-ups far outnumber error messages. I could not get Mac System 7.1 to work at all, or boot from the System 7.5 Group Upgrade CD. My A4091 and CyberStorm 060 combo clobbers Fusion's virtual memory, but it worked on the Warp Engine, favoured by Drew for development. ATAPI and NEC SCSI CD ROMs worked, but my Toshiba 3401 would not.

Comparisons

ShapeShifter seems to have got stuck at version 3.8, with no updates for the last six months; it lacks the extras in Fusion, like multiple-monitor support, virtual memory - nascent in ShapeShifter - AHI 16 bit audio, almost-direct SCSI for scanners, DATs and Music CDs, and System 8 compatibility. But ShapeShifter is much easier to get started, better documented, and given plenty of CPU power even supports sound input, still a ghosted option in Fusion's menu.

Both require at least a 68020 processor with Workbench 2, but Fusion's 'minimum requirements' are more exacting that ShapeShifter's. It demands at least Mac System 7.1, 4 Mb fast RAM, 20 Mb hard disk space and a high density floppy drive.

Mac system software is only sold on CD now, so unless you already have a full, generic intallation on a wad of floppies you need a CD ROM drive too. Systems for specific Macs often work on ShapeShifter, but lock up Fusion. Full sets cost almost one hundred pounds, with little discounting, but if you own the rights Apple's updater, on our CD canupgrade you to the full system 7.5.3 from just a Disk Tools disk.

Fusion can boot from current (system 7.6 or 8) Mac CDs but it helps to have a Disk Tools floppy to initialise your first hard disk partition. Real Mac drives come preinitialised, of course! The CDs include floppy disk images, but Disk Copy will only extract them without a genuine Mac SuperDrive. Other metal-bashing programs that fail include many MIDI packages - a great loss - RAMdoubler (so use real virtual memory) and NetBSD (use the Amiga version).

Fusion prefers AT LEAST 8 Mb RAM, 50 Mb hard disk space, System 7.5 or later, a 512K Mac ROM image, CD ROM and a processor with both FPU and MMU. System 8 requires a full Megabyte ROM image, patched by Fusion for any 32 bit CPU, where Apple require a PPC or full 68040.

Mac OS 8 demands 16 Mb RAM and about 100 Mb just to install, though you can trim the redundant PPC code with the 'fat stripper' utility. Typical games require 8 Mb on the Mac side, supported by two to 8 Mb just for the Amiga.

Without CPU-card expansion, Amiga users will struggle to make enough RAM available. Worse, all the memory needs to be in one contiguous block. Macs cannot cope with memory in 'fragments', as the Amiga system can, and often must.

Fusion's virtual memory support trades up to 767 Mb of hard disk space - and time - for real memory. Like all Fusion's wildest hacks, it's system -dependent and may be hard to set up, but crucial for compatibility with greedy programs like PhotoShop.

Without the support of MicroCode Solutions and Blittersoft, Fusion would be too 'bleeding edge' to be useable. It's a pig to start up and still needs more testing on the myriad potentially-suitable Amiga configurations. It's ambitious, clever and good value if you've got the time and patience to get to grips with it.

Fusion 2.0

DISTRIBUTOR: Blittersoft 01908 261466
PRICE: �49.95

Speed Impressive, when it works
Documentation Skimpy, and disk only
Installation Tortuous and frustrating
Compatibility Erratic till carefully tuned
Value Cheap by Mac standards
OVERALL VERDICT: Promising, but fragile.

70%

Mac	Amiga
Krek Waiter's Peak Mac A handy lexicon of Amiga and MacSpeak
Control Panels	- Preferences
Desktop	- Workbench
Dialog box	- Requestor
Extensions	- WBstartups
Folders	- Drawers
Initialize	- Format
Preferences	- EnvArchive
QuickTime	- CDXL

On AFCD 20

There's a treasury of Mac-emulation related utilites on AFCD 20
AMax	- Supra hard disk driver, flicker reducer and ROM accelerator
BootFile	- a cut-down Mac system 7.0 to get you started in ShapeShifter
CrossMac	- File system to read Mac disks on suitable Amiga drives
FAQs	- Amax, Emplant, Fusion, Mac and Shapeshifter answers
Emplant	- diagnostics, icons, screen and CD drivers for Jim Drew's debut
Emulators	- Amiga (really!), Apple ][, Atari, Beeb, Spectrum, TRS-80 etc.
MacJoy	- for Amiga joystick and CD32 joypad support to Mac emulators
MacApps	- Acrobat Reader, Disinfectant, Graphic Converter, Stuffit Expander
MacTools	- transfer and convert files between Amiga and Mac
MacView	- A vintage Amiga application to display MacPaint pictures
ShapeShifter	- Christian Bauer's shareware Mac 2 emulator and PD extras
Upgrader	- takes a minimal Mac System 7.5 up to full Apple specification

Web connections:

OCTOBER 2005 UPDATE! AF Fusion and ShapeShifter reviews	- (3,165K colour scan in PDF format, 7 pages of A4)
Apple computer	- http://www.apple.com
Macintosh PD	- http://hyperarchive.lcs.mit.edu/HyperArchive.html
ShapeShifter	- http://www.cebix.net/