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. The free emulators mentioned were included on the accompanying CD with the magazine, and are generally available - often in updated form - from this site. 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, care of Tomas Amsrud, who has generously prepared the material for publication on the Internet.

EMULATION
The sincerest form of flattery

Simon N Goodwin explores the history of
emulation and takes a in-depth look at all the
systems currently available to the Amiga user

The Amiga is a uniquely talented mimic. It can run programs for a wider range of computers than any other machine. Programs that make one computer work like another are called 'emulators', and represent the future of computing. They allow users to stick with the software they know and understand, as hardware platforms come and go at a bewildering pace.

More than fifty emulators run on the Amiga. Most multi-task, so you can emulate several platforms at once, on one machine. The most popular - including the majority of mass-market home computers - are supported by several emulators, with unique features. Reasons for running emulators include compatibility, price, availability, familarity and curiosity.

Amiga emulators are not just toys. Some are more capable than the machines they impersonate. Most are freely available. But hardware and software requirements vary, and some simply don't work at all. The aim of this feature, and regular columns that follow, is to sift out the stars from the non-starters, explaining what sort of system you need to run each emulator, and where you can go for software and support.

History

The idea of emulation dates back to the first computer, designed - but never completed - by Charles Babbage in the 1840s. In his 'Life of a Philosopher' Babbage explained that his Analytical Engine could perform ANY sequence of analytical operations on an unlimited number of figures, by trading time for capacity if necessary. In principle any computer can emulate any other - given unlimited time to do the job!

A century later codebreaker Alan Turing documented a 'Universal Machine' that could perform any computable process. In 1937 this was just theory, but within a decade Turing and others built working digital computers, and problems of software compatibility were beginning.

The time needed to develop new hardware is dwarfed by the time spent converting existing programs that people would like to run on the new machine. Many computers have arrived, and worked, but disappeared for want of software support.

Most programs supplied with the original IBM PC were machine-translated from old 8080 assembly language into code for the newer 8088. This squandered speed, but gave the PC a foothold, so that enough machines could be sold to justify writing genuinely new software.

When Apple introduced 'Power Mac' systems they used new, cheap and speedy processors instead of the tried and trusted 68000-family chips. At first the Power Macs ran almost entirely as emulators, via two utilities - one that decoded 680XX instructions and one for Intel 80X86 programs.

Even now the majority of Mac software is emulated, rather than run as 'native' Power PC code. Thre jury is still out on the Power PC itself - 68060 and even 486 processor boards are still selling well - but it seems clear that emulation is here to stay, and will be more and more important in the future.

Amiga users benefit from a decade of programming effort. You can find Amiga -specific versions of most common software tools, but there are some - like Excel on PCs, or PhotoShop on Macs - which have no equal on the Amiga. To run these, and stick with your existing Amiga investment, you need an emulator.

As computers advance it makes sense to use the hardware power of new machines to get old software working as soon as possible, even if it ends up slower than it might be if rewritten from scratch. Most emulators are slow because they must interpret and translate programs for one machine, instruction by instruction, to suit another, and it takes several new instructions to decode each old one.

Luckily computers keep getting faster so the overhead is tolerable, as long as you upgrade your hardware every few years. That's usually cheap compared with replacing all your software, not to mention the hassle of learning how to use the new stuff.

Compatibility

If you've already entered lots of data it can be difficult or time -consuming to convert it for a new package. With an appropriate emulator, you can carry on using your old software, and data. You might still need help to move the data onto the modern drives on your new machine, but a good emulator will make this relatively straight-forward.

Amiga 'handlers' can read disks from other systems as if they were in Amiga format. The best-known handler is Cross-DOS, bundled with Amigas since Workbench 2. This reads and writes the IBM PC disk format.

Others include AmiCDFS, BFFS, Cross-MAC, Messydos (for old Amigas) QLFileSystem and SP-handler. These do not solve the problem of running old software - they just transfer data from a variety of formats onto the Amiga - but they are often used by emulators to access files without worrying about where they're coming from.

Thus you can use PC, Spectrum, QL, MSX, Mac and Amiga floppies or CDs willy nilly, with no need to warn the computer or particular programs about what you're doing. If 720K and 880K formats are not suitable, HD, ED and old 5.25" minifloppy drives are available as options. The Amiga disk controller is unusually flexible, while other machines need extensive hardware modifications to read 'odd' formats, like genuine Amiga disks.

Several C64 emulators allow connections to old, peculiar 1541 drives, so users can move their files onto Amiga hard disks, where they can be accessed much faster and more conveniently. Most Spectrum software was distributed on cassette, so Spectrum emulators will load tapes through the Amiga's existing ports. Many emulators support serial transfers, so if you've still got an old machine you can squirt data from it directly into your Amiga.

These techniques involve a mix of hardware and software. On the hardware side, you may just need a suitable lead, although some adapters need extra components. These can be made up commercially for people who'd rather pay than do it themselves.

There are three ways to emulate hard drives. The simplest is to add an extra drive and dedicate it to a particular emulator. This approach works well with the built-in Emplant SCSI interface. It's more efficient to dedicate a partition - a section of an existing drive - to the emulator, storing files inside in the format expected by the emulated system. CrossDOS and BFFS handlers allow access to these files from Amiga programs, too.

The lazy approach is to create one big file on an existing Amiga partition, and treat that as a device in its own right, with emulator files and directory information inside. These 'Hard Files' work, but are slow because the Amiga may have to read most of the file to find a particular entry inside.

Amiga strengths

The Amiga design is particularly well suited to emulation. Amigas multi -task, so they can emulate several computers at once. Each program or emulator can have its own screen, so emulators can use the display format that suits them best, and the user can scroll or swap between them.

Modern Amigas display up to 256 colours in a variety of modes. This is enough for all the home computer displays but falls short of the latest Mac and PC screens, unless ingenious but slow HAM modes are used. PC Task, ShapeShifter and Emplant favour plug-in graphics cards like Picasso and Cybervision for more colours and easier compatibility. AGA graphics are slow when emulating systems with 'chunky pixels' so graphics boards are recommended for serious PC, Unix and Mac emulation in colour.

The Amiga's blitter can convert graphics automatically. QL and Atari ST screens use successive bytes for each colour, whereas the Amiga keeps each colour separately, as a 'bit plane'. Emulators use the blitter to extract interleaved bytes and write them to Amiga bit planes. Emulated programs carry on as if the interleaved display hardware is present. There's no need to intercept or translate each access to the screen.

The Amiga has hardware 'sprites' - image overlays that can move without disturbing the background picture. Sprites speed up emulation of similar hardware in C64 and MSX systems.

Amigas offer a choice of places to connect just about anything. There are three serial ports - the well-known one on the back panel, the keyboard one, and a third synchronous port, ideal for connecting C64 and VIC-20 disk drives and other custom serial devices.

Cassettes can load through joystick or serial sockets, or via a sound sampler and the parallel port. The controller ports suit light pens, guns, paddles and proportional controllers, as well as mice and digital joysticks, so emulator users can plug in their old peripherals and use them just as they would on the original system.

Commodore changed the Amiga keyboard for the A1200, and this upsets some emulators. The A1200 - like most Macs - cannot detect combinations of more than two keys. This cripples keyboard controlled games - you might press two keys to move diagonally, and find that the third 'fire' button is not recognised. Joystick emulation can circumvent this A1200 fault.

Rights and ROMs

Emulators recreate the software environment of the original computer, as well as the hardware. This usually involves running a copy of the built-in 'ROM' software, copyright property of the original manufacturer. For legal reasons, many emulators expect you to provide your own ROM image, particularly if you get the program from a large, international supplier like Aminet. Amstrad is the main exception, generously allowing their eight bit ROMs to be freely distributed with emulators.

Otherwise you need to make your own copy and transfer it to the Amiga by tape, disk or serial link, or track down a ready-made image on the Web or an FTP site. It is legal to use an image of software you already own in an emulator, but you should not grab a copy from someone else's computer and use it at the same time as they use the original. That's copyright theft.

The position is similar when it comes to emulator applications and games. Program snapshots and disk images are available on CDs and on the net, and it's quite legal to use them if you own the original.

Such files are convenient because many old programs came on protected disks or cassettes, hard to load on the original machines, let alone the emulator. But there's nothing - apart from the lack of instructions - to stop people who do not own the originals from swiping free copies of other people's copyrighted works. This frequently causes legal hassle.

Cross Emulation

It's quite feasible to run one emulator on another - indeed, it's a good way to get the best emulation possible for a particular processor. One of the emulators should be running programs in native code . It's bound to be too slow if you've got one processor interpreting instructions for a second, to interpret a third.

Apple Macs emulators for Spectrum and C64, among others, work well on the Amiga under Shapeshifter or Emplant. I tested Mac Speccy 1.1 and Mac Spectacle 1.5 on an A4000/040. Mac Speccy 1.1 is PD, fast and works well even on a two-colour ShapeShifter screen. Mac Spectacle is slower and needs at least 16 colours, letting you stretch and shrink the screen arbitrarily to suit your desktop. It's Ł10 shareware, from Dublin.

Emulators for Qdos proliferate, especially for ZX Spectrum, unsuprisingly in view of its heritage. Most work well under Amiga Qdos, including Speculator 93, the PD predecessor of Amiga Speculator, which I helped to develop, and Xtricator, a ZX-81 emulator. There are two good emulators for the Spectrum 128: ZM/3 and Spectator.

The most interesting Qdos emulator is ZM/HT, an advanced cross compiler which generates 68000 programs corresponding to Spectrum code on the fly. It's an awesome feat of computer science, and the only Z80 engine that runs at a reasonable speed even on standard 68000s. It's published by Ergon of Italy, with demos in Qdos PD libraries.

NetBSD, recently reviewed, is not an emulator but a replacement operating system. This Amiga version of Unix supports many emulators written for work -stations and distributed as C source code. Most need a colour X window display on a graphics card or separate X terminal (possibly another Amiga!). Thus sorted, you could run emulators for Spectrum, TRS-80, Apple 2, PC, SAM Coupe and many others, as well as Unix applications.

UAE

They said it could not be done and - for a decade, at least - they were right, but at last there's a working emulator that runs Amiga programs on other platforms. It's called UAE, originally known as the 'Unusable Amiga Emulator', even to its authors, as it was horribly slow and unreliable. Since then it's been upgraded to the point where some report that it runs hardware-banging games like Turrican and Amiga Worms at sensible speeds, at least on a 133 Mhz Pentium or faster...

UAE is written in C and has been compiled on various workstations and power desktop computers, including PCs, Macs and Unix boxes. There's even a version ported to the Amiga itself, courtesy of Olaf Barthel, and while this may seem the height of gratuitous hackerdom it presents a practical way of running old Workbench 1.3 titles, with emulation of useful hardware like Action Replay, on otherwise incompatible top-flight Amigas with Workbench 3.1 and 68060s.

UAE emulates the Amiga 500/1000/2000. All you need is a Kickstart ROM image to get it running. The first version was pathetically slow because it did real-time emulation of all the custom chips and DMA channels, but the current version is relatively useable as it takes short cuts when it realises that a particular feature is not required. There's still a hardware problem with genuine Amiga disks, as only a real Amiga can read or write them, but you can get around this by loading disk images.

Authentic Amiga owners can sleep easy - UAE is slow on any but the fastest modern computer, and no match for an A1200 on any platform yet. It has bugs, and will need a lot of work to add support for AGA and 68020 instructions, even when computers are fast enough to make this a practical proposition. Even so it's an impressive achievement and - unlike several spoofs - it really does emulate the Amiga convincingly. UAE proves that any sufficiently fast computer can emulate any other. Emulation is truly the future of computing.

C64 emulators

The Commodore 64 was the Amiga's precursor, from the same company, and many owners graduated to the Amiga. C64 was the first popular emulator, still available in version 2 from many PD libraries. It's slow but usable, even on an unexpanded A500.

Requests to load files and directories access Amiga disks, rather than the amazingly slow Commodore 1541 drive. It works like a real C64, with arcane commands like LOAD "$",8:LIST to see the directory of a disk! Sound and sprites are emulated well, although sprites may flicker as ECS Amigas do not support the full C64 sprite width.

Later emulators have concentrated on accurate emulation of hardware tricks used in C64 demos, trading speed for accuracy of emulation. The most extreme is Frodo, which needs a very fast Amiga to run at full C64 speed, but can emulate almost all the 64's hardware peculiarities.

A64 misses a few hardware tricks but is perhaps the most polished C64 emulation, with a built-in machine code monitor and support for genuine C64 hardware via the third serial port. It's shareware from PD libraries. The full version is on C64 Sensationscompilation CDs.

Magic 64, from Germany, won't save and lacks sound unless registered, but emulates most of the C64 graphics. AXF-64 is less comprehensive, but faster on limited hardware. Amiga C64 emulators do not seem to like Multisync displays, and I needed to disable mode promotion to get them to work on my A4000.

PC emulators

IBM-compatible PCs are the commonest computers in the world; several software-based Amiga emulators run PC programs, but they're rather slow and limited. The shareware leader is Chris Hames' PC Task, currently at version 3.1. This emulates an 80286 processor (vintage 1982) with support for Amiga hard drives, printers and CD ROMs. The unregistered version will not write to disk.

I've used a registered copy of PC Task 2 for several years, and found it a reliable, if slow, MSDOS emulator. The main advantage of PC Task 3 is emulation of VGA and some SVGA graphics modes, using AGA hardware.

PC Task can just about run Microsoft Windows, but painfully slowly. On the fastest 68060 Amigas it's the speed of an average 386; a 4000/030 runs PC code at half the speed of an old AT 286.

PC Task's main rival is Emplant 586, from Utilities Unlimited. This 486 emulator supports the improved instruction set of later Intel processors as well as floating-point operations, but it's still software based and runs at a fraction of the speed of a 'real' 486 - or 586, for that matter. It requires at least a 68020 with Workbench 2, and displays are sluggish unless your system has hardware memory management.

It's hard to get Emplant 586 running because it needs a copy of the BIOS software from a real PC. That involves moving a PC chip to the Emplant hardware, and running an Amiga program to snaffle the code. Utilities Unlimited claim that almost any BIOS will work, but users report otherwise.

Commodore once bundled a PC emulator called Transformer with Amigas. It worked, even on an A500, and is still available from some PD libraries, but it's desperately slow. The 'Landmark' benchmark rated it as a 0.3 MHz 286, a small fraction of the speed of IBM's first, slowest model. Transformer only runs on 68000-based Amigas, needs two disk drives, and crashes if it finds more than 512K of chip memory.

IBeM is another shareware PC emulator, compatible with processors from 68000 up to 68030. It emulates MDA text and CGA (four colour low res) graphics, but it's even slower than PC Task - Landmark rated our 25 MHz A4000/030 as a 1.3 MHz 286! The shareware version is limited to a 2 Mb hard disk partition and stops automatically after 15 minutes.

There have been hardware-based PC emulations, most notably Commodore Bridgeboards and the AT-Once and Golden Gate models from German firm Vortex. These out-perform software-based emulators, but they're still slower than modern PCs. I'll discuss these, and the problems of software PC emulation, in detail in a forthcoming column.

Spectrum Emulators

Amiga emulators abound for Sinclair's ZX Spectrum, a simple, popular Z80 based home computer. The first only worked on original 68000-based Amigas. New emulators run Spectrum programs at full speed, given a 25 MHz 68030 or better.

First out was 'KGB Spectrum' which ran - rather slowly - on 68000-based Amigas only and was incompatible with Kickstart 2. It was written by Troels Noerdergard of Denmark, and reached version 1.3, running snapshot files from Amiga disk. A snapshot is an image of computer memory - in this case, 48K plus a few bytes of processor context.

Until recently the king of Spectrum emulators was Peter McGavin's Spectrum version 1.7. Some PD libraries have this marked up as version 2.0, but the documentation and program seem unchanged since 1.7. It loads snapshots from Amiga disks and cassettes via a sound sampler.

This 48K Spectrum emulator runs on any Amiga, from an old A500 with Workbench 1.2, to the latest A4000/060. It's slow, like all Z80 emulations, on a 68000; you need an accelerated A1200 to run programs at full Spectrum speed. A500 and A600 owners can still have fun with text adventure games, widely available as Spectrum PD.

ZXAM is a more recent release, by Tony Pomar of Spain. Originally AGA-only, it now runs on Amigas with at least Kickstart 2 and a 68020. A special version is needed for 68060 systems.

ZXAm is not the fastest, but has lots of nice Amiga-friendly features. It multi-tasks and supports AREXX. It can load cassettes via the joystick port and a small hardware adapter. It emulates the three channel Spectrum 128 sound chip, as well as the basic Spectrum hardware. A full Spectrum 128 version is in the works.

ZX Spectrum 4.71 is written by Jeroen Kwast for all Amigas. It's shareware and supports programs that use Sinclair's Interface 1 Spectrum add-on, although the required ROM image is not included. It includes a screen-print option. Despite the high version number, it's buggy and crashes on 68040 or above, even with caches disabled.

William James' Speculator is the latest Amiga Spectrum emulator. It out -runs the rest on some programs, and has several unique features. Keyboard handling is the best of the bunch and it can read lots of snapshot formats, although it needs particular file-name extensions to correctly identify some. It supports cassette loading via a simple lead, serial transfer from real Spectrums, and includes a handler to read MGT format Spectrum disks just like standard Amiga or PC ones.

Speculator comes with a good manual and Z80 software tools including a labelling disassembler and a fast cross-assembler that runs as an Amiga task. Spectrum printer commands LPRINT and LLIST are re-directed to the Amiga printer device, and it can compress snapshots and save screens.

Unusually, Speculator translates Spectrum display updates into Amiga form on the fly, rather than periodically rewriting the entire screen. This makes it faster and smoother on some programs, but slower on others. It supports multisync graphics modes, scan doubling to keep the picture size consistent, and suits all Workbench 2 or 3 Amigas.

Mac Emulation

One of the most successsful areas for Amiga emulation is running Apple Macintosh software. Until recently Mac hardware was very expensive, even by Amiga standards, yet Macs were based on the same 68000-family chips as Amigas. Consequently Mac programs run on the Amiga without translation, as fast as real Macs with the same processor. And since the Amiga - unlike the Mac - is a multi-tasking machine, you can run other programs at the same time.

Amiga Mac emulators use a copy of the Mac system, normally held in a ROM chip and on disk, and intercept attempts to access Mac hardware, re -directing them to Amiga ports. It helps that most Mac programs are 'system -friendly' and rarely try to use Apple hardware that may not exist in the emulator. The main exception is Mac MIDI programs, which try to hit the Mac serial port directly, and fail on emulators.

Older Macs had vari-speed disk drives, incompatible with all other computers. The first successful Amiga Mac Emulator, AMax, addressed this with hardware to connect a real Apple drive to the Amiga. Modern Macs use standard drives, compatible with HD drives in the Amiga 4000 and available as add-ons for other models.

Emplant is a very successful Mac emulator, based on a Zorro 2 card which serves as a 'dongle' to prevent illicit copying of the emulation software. Sockets allow Mac ROM images to be copied to Amiga drives. Optional 'AppleTalk' Mac networking hardware is great if you want for linking Amigas and real Apples. Other options include a rudimentary SCSI interface and a sound input port, as yet unsupported.

Emplant ruled the roost for years, but it's been overtaken by ShapeShifter, a shareware Mac emulator which needs no special hardware. You still need a Mac ROM image, but Emplant comes with software for real Macs running system 7 or later, which copies the ROM to a PC-format disk for transfer to the Amiga. Both are Mac 2 emulators, requiring at least a 68020 and System 7, which you can download from Apple or find on Mac magazine cover CDs.

The unregistered ShapeShifter is quite usable, although it only supports hard files rather than hard disk partitions, making disk access very slow unless you allocate a few hundred K of disk buffers for the relevant partition. I use the command ADDBUFFERS MISC: 1000 where MISC: is the device containing the hard files, immediately after starting the emulator. Registered users can access hard disk partitions and SCSI devices directly, making file access much faster.

ShapeShifter has garnered more than 3,000 registrations at a price of $40 or DM 50, prompting Utilities Unlimited to produce an undongled version, Emplant Lite, for A1200 as well as A3000 and A4000 systems.

Both Emplant and ShapeShifter work well on a monochrome screen, as on original Macs, but become painfully slow in colour, even on AGA Amigas. The 16 colour ShapeShifter driver is almost unusable, and the 256 colour version is hopeless, even on fast Amigas. PD drivers improve the situation, but colour displays are still slow and jerky compared with a real Mac.

Emplant fares better, thanks to patches into the Mac system which adapt it better to Amiga planar graphics, but both benefit spectacularly from the presence of Zorro graphics cards, which support Apple-style chunky pixels. The 256 colour, 1024x768 pixel picture here comes from an A4000 with a Picasso 2 graphics card. The combination of a fast A4000 and Zorro graphics card gives very convincing Mac emulation, and you've still got an Amiga in the same box.

Other emulations

Amigas can emulate most other mass market home computers, including the Atari ST, Acorn BBC Micro, Amstrad CPC, Sinclair QL, Atari 800, Commodore VIC 20, Oric Atmos and Tandy TRS-80.

Atari ST and Sinclair QL emulations are fast, as those machines use Motorola processors. I still use an ST emulator on my A500 to run the Atari version of 'AutoRoute'. The emulator works well with utilities and productivity software, but does not support hardware-banging ST games at all. Unfortunately the ST system software (GEM and TOS) is 68000-specific and will not run on faster processors.

Sinclair's QL was based on the eight bit version of the 68000, Motorola's 68008. It came out a year before the Amiga, with an excellent built-in programming language, SuperBASIC, reasonable graphics, and Qdos, a multi -tasking operating system. Emulation is almost perfect, although you need a 68030 or better for more than four colours.

Amiga Qdos suits processors from 68000 to 68060 and comes with Psion Xchange, a rather good floppy-based integrated business package with word -processing, spreadsheet, database and business graphics features. Psion allow this to be distributed on the emulator support disk, along with many Amiga-specific extensions.

Amiga Qdos comes complete with a handler to read and write Qdos floppy disks from the Amiga desktop, full source code and all the tools you need to re-assemble your own version. Modern Amiga owners should be sure to get the current version, 3.23; earlier ones were not compatible with AGA or faster processors.

The VIC 20 emulator, Apple 2000, AmOric and EmuCPC are among the best of the Amiga home computer emulators. All are system friendly and run lots of software without problems. You need ROM images, and at least a 68020, and preferably a 68030 or better, to play games at full speed.

The TRS-80 Level 3 emulator also works well, although written in compiled C and thus a bit slow. The BBC emulator is fast because most of the ROM has been rewritten in Amiga code, but has problems with unimplemented instructions on 68010 and above. To cure this try TUDE, an Aminet utility.

Two Amiga emulators support the MSX range of Japanese micros with Z80 processors, Microsoft ROMs and Texas Instruments display chips. The disk format matches PCs and the sound chip was used in the Spectrum 128, BBC Micro and Amstrad CPC, so emulation is tried and tested.

FMSX hails from The Netherlands. It is freeware, but rather slow. It requires at least a 68020 and Workbench 2. MSX2 is time limited shareware from Spain. It has the same minimum requirements but runs substantially faster.

The Amiga TI 99/4 emulator works, but it is very limited and has not been updated past version 0.1 for some time. The same goes for A4, an Austrian emulator for Commodore's C16 and Plus 4 home machines. Both require ROM images.

There's rumoured to be a Dragon 32 emulator in the works, and there's a good one for the text-based operating system Flex, which uses the same 6809 processor. CP/M emulators are similar, but mimic early Intel and Zilog -based business systems. I've been unable to get the GameBoy emulators to work, and have yet to try the Atari 800 one. Expect updates on these, and others, in future columns.

Computer Glossary
Apple 2	One of the three first home computers (with Commodore's PET and Tandy's TRS-80 Model 1).
C16	Commodore 16, a cut down home micro similar to the C64 and Commodore Plus 4 - the home/business version of the C16.
C64	Commodore 64, best-selling 64K eight bit computer of the mid 1980s, made by the firm that later introduced the Amiga.
CPC	Amstrad's eight bit, Z80-based home computer, rival to Sinclair's ZX Spectrum and the Acorn BBC Micro.
CP/M	Control Program for Microprocessors - the first operating system to bridge the gap between diferent manufacturer's machines so they could share software; the precursor of MSDOS.
Mac(intosh)	Apple's range of computers based on ideas invented at Xerox Palo Alto Research Centre, birthplace of Mice, Windows and Pointers.
MSDOS	Crude single-tasking IBM compatible PC operating system.
MSX	An eight bit home micro standard adopted by many manufacturers, mostly Japanese. Based on Microsoft ROMs & chips from the USA.
Oric	Eight bit British home computer, a rival to the Spectrum with better sound but less software support. Later sold to the French.
PC	Personal Computer - usually refers to machines compatible with the Microsoft and Intel-based systems introduced by IBM in 1980.
QL	Quantum Leap - the only British home computer based on the Motorola 680XX processor range, introduced (prematurely) in 1984.
TRS-80	Tandy's brand name for computers, mostly based on the Z80 processors with crude mono graphics and up to 48K of memory.
VIC-20	Another Commodore micro, predecessor to the C64 but with just 5Kof memory and relatively simple graphics.
ZX 81	The cheapest home computer ever made, and an introduction to micros for millions in the early 1980s: under Ł100 with 1K RAM.
ZX Spectrum	The best-selling British micro ever, introduced by Sinclair in 1982 and subsequently developed by Amstrad. More famous for cheap and playable software than for its simple but effective hardware.

CD Emulator Compilations

TheSpeccy 96 CD contains snapshots of thousands of Spectrum games, half a dozen Amiga Spectrum emulators and others for PC, ST and Acorn Archimedes. It's a mixed bag, padded with over 50 Mb of unrelated files from Aminet late last year, about 100 Mb of PC shareware and 55 Mb of clip art, with the Amiga GIF viewer VT.

Nonethless this is the most comprehensive collection this side of of ftp.nvg.unit.no, and contains almost all the old Spectrum hits. The title most notable by its absence is David Braben's Elite, pulled after legal hassle. You also get Spectrum FAQ files (Frequently Asked Questions, with answers) and Spectrum manuals, supplied as ZIP archives in ASCII and Microsoft 'Write' formats.

64 Sensations Volume 2 is a strange collection. It includes full versions of the Amiga C64 emulator A64, Frodo (with source!), AXF-64 and Magic 64 (unregistered), a couple of PC Commodore 64 emulators, and one for Apple Mac (or emulations). Most of the disk is occupied by hundreds of tunes for the C64 SID chip, with an Amiga player, and thousands of demos and disk magazines, some dating back more than ten years. Games are notable by their absence - reputedly because of legal problems with Volume 1.

Despite its name, the 64 Sensations disk contains other Amiga emulators besides C64 ones. There's a rare Atari 800 emulator, Apple 2000 with the necessary ROM image, and the latest Emplant software, plus C64 emulators for PC and Mac.

Emulators Unlimited is an Amiga-specific compilation, best described as 'shovelware'. Some of the emulators are way out of date - the Amiga Qdos version is the second release, more than six years old, buggy and incompatible with AGA. The IBeM directory contains a shareware update without the documentation or mountlist needed to use it. The PC AT-emulator is useless unless you own AT -Once A500 hardware. Some of the 'emulators' are useless spoofs, and the Amstrad directory only contains the very limited CPE.

Despite its shortcomings this CD contains things that are available nowhere else, including lots of emulator source files, over 250 genuine C64 games and 2000 demos, hundreds of Spectrum snapshots and games for PC, Oric and Apple 2. There are ROM images for VIC, C64, Oric and Amiga. Useful though these undoubtedly are, some of them are clearly infringing copyright, and should not be used unless you already own legitimate copies.

Contact: Weird Science Ltd, 1 Rowlandson Close, Leicester LE4 2SE.

Acronym Glossary

AF - Amiga Format, best selling Amiga magazine!
AGA - Advanced Graphics Architecture - current Amiga graphics.
C - A processor-independent (ish) system programming language.
DMA - Direct Memory Access, doesn't slow down the main processor.
ECS - Enhanced Chip Set - A600 & most older Amiga graphics chips.
ED - Extra Density - floppy disks with a capacity around 3 Mb.
HD - High Density - floppy disks with a capacity around 1.5 Mb.
Mb - Megabytes - thousands of K, or millions of bytes (roughly).
MIDI - Musical Instrument Digital Interface, for synths and sequencers.
PD - Public Domain - freely distributable software or information.
RAM - Random Acess Memory - changeable, lost with power off.
ROM - Read Only Memory - permanent fixed storage for system code.
SCSI - Small Computer System Interface - for up to seven fast drives.
X - A workstation graphical windowing system descended from W.
Z80 - The best-selling eight bit microprocessor, made by Zilog.

AMIGA EMULATOR LOCATOR

Most emulators are available from Aminet, in the misc/emu directory. If you have no modem or CD ROM drive, check out regular Amiga PD suppliers, most of whom have a good selection. This is not a complete list, but a good start. There's a selection of emulators on our cover CD, with more to follow. Check the new AF series for more emulator details, contacts and support.

Status codes:
S=Shareware
F=Free
C=Commercial

Recommended CPUs:
0=68000 only
1=68000+
2=68020+
3=68030+
4=68040+

Programs coded 0 need patches to run on CPUs other than 68000. Code 2 titles require an A1200 or better (speed, WB3 or 68020 instructions required). Most systems marked 3 will run, albeit very slowly, on a standard A1200.

Status

Programs

CPU

A-CPC Amstrad 464/664/6128 emulator

A4 Commodore C16 and +4 emulator

A64 Commodore 64 emulator

Ami-CPC 6128 emulator

Amiga Qdos 3.23, QL emulator

AmOric Oric 1 emulator

Apple 2000 emulator

AppleOnAmiga, Apple ][ emulator

Atari 800 emulator

Atari ST emulator

AXF-64 Commodore 64 emulator

C64 Emulator v2 (A500)

Emplant 586DX emulator

Emplant Mac 2 emulator

FMSX,MSX 1 emulator

Frodo, C64 emulator

KGB Spectrum emulator

Magic64, C64 emulator

McGavin Spectrum emulator

MSX2 emulator

PC-Task PC emulator

Shapeshifter Apple Mac emulator

Speculator Spectrum emulator

Texas TI 99/4 emulator

Transformer PC emulator

TRS-80 Model 3 emulator

UAE, Amiga emulator

VIC-20 emulator

ZXAM Spectrum emulator

Where to get programs:

0 - Aminet: /misc/emu
1 - Qubbesoft PD, Brunwin Road, Rayne, Braintree, Essex CM7 5BU, UK.
also SJPD, 36 Eldwick Street, Burnley, Lancashire BB10 3DZ, UK. Both have Amiga Qdos 3.23 and hundreds of PD QL disks.
2 - Atari, C64, C16/Plus4 and MSX software: ftp://ftp.funet.fi /pub/atari, /pub/cbm/c64, /pub/cbm/plus4, /pub/msx
3 - Amstrad emulators and ROMs: ftp://ftp.ibp.fr/pub/amstrad/emulator
4 - Mac systems & support: ftp://ftp.support.apple.com
5 - TI/994A files: ftp://solutions.solon.com/pub/ti99/
6 - Spectrum programs and documentation: ftp://ftp.nvg.unit.no/pub/sinclair
7 - VIC-20 archive: ftp://ftp.hrz.uni-kassel.de/pub/machines/vic-20
8 - PC: PD Soft, 217 Hamstel Road, Southend on Sea, Essex SS2 4LB.
9 - Apple 2 files: ftp://ftp.uni-kl.de/pub/apple2
10 - Oric files: http://arlesienne.ensica.fr/LOCAL/ORIC
11 - Atari eight bit files: ftp://atari.archive.umich.edu/atari/8bit/
12 - TRS-80 programs: ftp://ftp.kjsl.com/tandy (11pm to 6am GMT)

EMULATIONThe sincerest form of flattery

Simon N Goodwin explores the history of emulation and takes a in-depth look at all the systems currently available to the Amiga user