Section 1 Types of Emulation

SheepShaver (MacOS Runtime Environment)

Section 2 SheepShaver, continued
Section 3 Emulators

Game Emulators

Chapter Summary

In This Section:
Types of Emulation

SheepShaver (MacOS Runtime Environment)

System Requirements
Acquiring SheepShaver
Installing SheepShaver
Launching SheepShaver
SheepShaver Settings
Memory Settings

When you use a computer, you don't think about the hardware you're running--you're immersed in a
visual environment governed by the operating system and its applications. Whether you're deep in the
dungeons of Doom or typing away in a BeatWare Writer document, your hardware fades into invisibility
as the interface takes over. But the environment suggested by the operating system is never absolute--just
because most of your apps conform to the general appearances and behaviors of the BeOS universe, that
doesn't mean that all of them have to. When you're playing a full-screen game, for example, the game
emulates another world within the context of BeOS.
But why stop with spaceports and mystical worlds? Why not emulate entire operating systems running
on other types of hardware? BeOS emulators exist to let you run a copy of the AmigaOS or the MacOS
inside a BeOS window, play Nintendo cartridge games in system RAM, or pretend that you're sitting at
the helm of an ancient Sinclair Spectrum.

While some people experiment with emulators out of curiosity rather than necessity, a well-implemented
emulator can save you from having to reboot by enabling you to accomplish tasks that normally can only
be done in another system. This chapter offers only a brief overview of the emulators available for BeOS
as of R4.0. Some of the emulators covered here (like SheepShaver, the MacOS emulator, which isn't
truly an emulator at all) can be genuinely useful, while others (like BeBeeb, the Acorn Micro emulator)
are probably around only for nostalgia's sake.

In this chapter, the term "host system" refers to the primary running operating system--the OS that
booted the machine and that has ultimate control over the physical hardware. The term "alien
system" refers to the OS being emulated, since it's being run outside of its natural home. There is
no intended implication that some of these operating systems seem to have been designed by
aliens.

Types of Emulation
Before we dig in, it's important to distinguish between true emulation, where the emulating software actually mimics
another platform's hardware, and "runtime environments," where the original hardware is not emulated and a sort of
"negotiating layer" is used instead.

What's the distinction? As seen in Figure 1, when the alien OS cannot use the machine's physical hardware, an
emulator must fool it into thinking that the hardware it wants is actually present. But it's not enough to just emulate a
physical hardware environment in software. If you want access to your disk drives, and want your monitor and
keyboard to work, the emulator has to communicate hardware calls back to the host OS, which in turn sends them to
the physical hardware. Understandably, this process consumes a lot of resources, which usually makes true emulation
cumbersome and slow. In fact, it's theoretically impossible for a system to run in emulation as quickly as it does on its
native hardware (however, older operating systems are often emulated on current hardware, making it possible to
more than compensate for performance penalties).

Figure 1
If the alien OS requires different hardware than that which is physically present in the machine, a true emulator is
required to create the illusion of that hardware in system memory. If both BeOS and the alien OS are compatible
 with the physical hardware, emulation is not required. Instead, a "runtime environment" is used to negotiate
between the two systems.

On the other hand, if both operating systems expect to find the same physical hardware in the machine, there will be
no reason to emulate the hardware.

Staying Legal

In most cases, emulators do not include the operating system being emulated; they only provide an environment in
which that system can run. This means that you must already own a legal copy of that system. If the system being
emulated is already on your own hard drive (as is the case when you have both MacOS and BeOS installed on one
machine and use SheepShaver to run MacOS from BeOS), no problem. But in some cases the process is much more
involved. With the Un*x Amiga Emulator, for example, you must make a copy of your Amiga's ROM and transport
it to your BeOS machine. In order to obtain an Amiga ROM, you must own an Amiga computer (or purchase the
ROM separately through a legitimate vendor). The Web sites providing emulators won't help you obtain ROMs, and
neither will this book. In fact, it is for this reason that we weren't able to test all of the emulators described in this
chapter.

So does this imply that emulation is a shady business, or in any way illegal? That depends on how you go about it.
In the case of older hardware where the original company has gone out of business, emulators and ROM images are
sometimes traded freely on the Internet, perhaps with the assumption that no one cares (though you have a
responsibility to find out). In the case of still-active companies, a strong distinction needs to be made between the
emulator itself and the system code that runs inside it. Anyone can legally download and own an emulator, but
using an OS or game ROM you don't legitimately own is theft.

All that's required then is the presence of a software layer that knows how to manage traffic between the alien OS and
the host OS. This layer is called a "runtime environment," and its job is only to negotiate communications, not to
emulate hardware. As a result, runtime environments are faster than true emulators. A runtime environment is also
sometimes referred to as a "virtual machine."
To take an example, consider the Un*x Amiga Emulator (UAE), which lets you run AmigaOS within BeOS,
regardless of whether you own a Mac or an x86 machine. Because the Amiga's hardware is different from both the
Mac and the x86, AmigaOS needs to have that hardware emulated; thus UAE is a true emulator. On the other hand,
consider SheepShaver, which lets you boot and run MacOS in a BeOS window. Because both MacOS and BeOS
know how to communicate with PowerPC hardware, hardware emulation is not necessary. Instead, MacOS can be
made content to run inside of BeOS by providing it with a negotiating layer that knows how to turn MacOS system
calls into BeOS system calls, so that you can, for example, copy and paste data back and forth from one operating
system to the other. This is an example of a runtime environment, not a true emulator. It also explains why
SheepShaver can run MacOS inside BeOS just about as fast as it would run natively.

SheepShaver (MacOS Runtime Environment)

by Henry Bortman

SheepShaver is a runtime environment that allows you to use the MacOS side by side with BeOS. Of course it works
only on MacOS systems supported by BeOS. It does not run on Intel boxes. SheepShaver appears as an application
icon on the BeOS Desktop. When you launch it, it boots the MacOS within a BeOS window or workspace. Once the
MacOS is active, you can run Mac applications and perform network activities just as you would directly from within
the MacOS itself. SheepShaver is not a MacOS emulator. It runs the MacOS as a native PowerPC runtime
environment. As a result, its performance is excellent (in full-screen mode; see Display Modes, below). For most
activities, SheepShaver is as fast as running the MacOS directly on the same machine.

Figure 2
SheepShaver running the MacOS within a BeOS window; Microsoft Word 6.0.1, Photoshop 5.0, and QuarkXPress
4.0 are all active.
SheepShaver's creators, Christian Bauer and Marc Hellwig, claim that in theory any application that will run under the
MacOS should run under SheepShaver as well. In practice, it's not that simple. As Figure 2 shows, I was able to get a
number of popular applications, including Word 6.0.1, Photoshop 5.0, and QuarkXPress 4.0, to run successfully under
SheepShaver. I also succeeded in printing and in transferring files to and from another Mac with MacOS file sharing.
That's the good news. The bad news is that it took several hours of tweaking to get everything to work (see Known
Problems and Troubleshooting, below). And I never did get my modem to work properly. Be forewarned that software
that accesses the Mac's hardware directly--many games fall into this category--is likely to cause problems.

System Requirements
SheepShaver 1.1 (the current version at the time of this writing) will run on any MacOS system that supports BeOS.
This includes multiprocessor systems, although the MacOS applications that run within SheepShaver can't take
advantage of the multiple processors.

SheepShaver supports versions 7.5.2 through 8.1 of the MacOS. Support for MacOS 8.5 is in the works. On the BeOS
side, SheepShaver requires BeOS for PowerPC R3. (SheepShaver 2.0, when it becomes available, will require BeOS
for PowerPC 4.0.)

To install SheepShaver, you will need 300K of free hard disk space on your BFS volume. To run SheepShaver, you
will need a minimum of 16MB of physical RAM. Of course, you'll also have to have at least one MacOS partition
available that contains a bootable version of the MacOS.

Acquiring SheepShaver
SheepShaver is available only as a download from BeDepot. Both a trial version and a fully functional shareware
version ($50) are available. In the trial version, full-screen mode is disabled and an annoying message pops up on
your screen every couple of minutes reminding you that you haven't paid yet. When you pay the shareware fee, you
will receive by email a "key" file that enables full-screen mode and disables the warning messages. If you plan to use
SheepShaver regularly, pay the shareware fee. You get way better performance in full-screen mode--not to mention
the karmic benefits.

Installing SheepShaver
SheepShaver installation is simple: SoftwareValet does all the work for you. When you double-click the SheepShaver
Trial.pkg icon, the BeOS will launch SoftwareValet. If this is the first time you've used SoftwareValet, it will present
you with several configuration options (see Chapter 10, System Tools and Utilities for more on SoftwareValet). Once
you get past this initial screen, you'll be given the opportunity to install SheepShaver.

By default, SheepShaver will be installed in the apps folder of your BeOS boot drive. Unless you have a good reason
to change this location, stick with the default. SoftwareValet will also give you a choice between Standard and
Minimal installs, but actually it doesn't make any difference which one you choose. If you've configured
SoftwareValet to display installation previews, when you click the Begin button, a Preview Install window will open,
showing you where SheepShaver's various files will be installed. Again, unless you know what you're doing and have
a good reason for doing it, stick with the defaults.

When the installation finishes, a SheepShaver registration window will appear. See Chapter 10, System Tools and
Utilities, for more information on registering software with SoftwareValet.

Launching SheepShaver

Performing a few setup tasks before launching SheepShaver for the first time will make things go more smoothly.

Make sure that virtual memory is turned off in the MacOS Memory control panel. Don't worry, you don't need it
anyway. SheepShaver uses BeOS's virtual memory system, which is superior to the Mac's.
Disable all Mac extensions that you don't really need. SheepShaver is prone to extension conflicts. The fact that
an extension works when you run the MacOS directly doesn't guarantee that that same extension will work
under SheepShaver. The following extensions are known to cause problems: RAM Doubler, Speed Doubler,
MacOS Licensing Extension, and 68K FPU emulator extensions (such as PowerFPU); but this is by no means a
comprehensive list.
Once you get SheepShaver working, you can start reenabling your favorite extensions. An extension-
management utility like Conflict Catcher or Now Startup Manager is helpful for this task; the MacOS's built-in
Extensions Manager will work, too, but it lacks some useful bells and whistles.
If you intend to use AppleTalk network services from within SheepShaver, make sure that you have set up an
Ethernet interface in the BeOS Network preferences panel (see Chapter 9, Networking, for details). Of course, if
 your Mac doesn't have Ethernet, you can't very well set up an Ethernet interface for it in BeOS. See Network
Settings, below, for what to do in this case. LocalTalk networking is not supported.
In BeOS, mount any Mac volumes that you will want access to from within SheepShaver. This includes
removable cartridges.

Launch SheepShaver as you would any other BeOS application, by double-clicking its icon. Before the MacOS
environment appears, SheepShaver displays a SheepShaver Settings panel, in which you can configure various aspects
of the program's behavior. Details about these settings are described below in SheepShaver Settings.

The first time you launch SheepShaver, it will boot the MacOS from the first boot volume it finds,
regardless of which volume is designated as the startup disk in the MacOS's Startup Disk control panel.
If you want SheepShaver to boot from a specific MacOS volume, you must select that volume in the
Startup Disk control panel from within SheepShaver.

If you have any Mac volumes mounted in BeOS that you have added Figure 3
to the SheepShaver volumes list, a warning similar to the one in Figure SheepShaver warns you before attempting
3 will display for each volume before the SheepShaver window to mount HFS volumes that are already
appears. If this warning appears, click the OK button (you don't have a mounted in BeOS.
choice). But be aware that SheepShaver is not always successful at
automatically unmounting these volumes. And if SheepShaver can't
unmount a volume, your Mac could hang. A safer approach is to
manually unmount HFS volumes from BeOS after you have added
them to the SheepShaver Volumes list (see Volumes Settings, below).

The first time you run SheepShaver, a warning will appear asking you
whether you want your network configuration modified to support Figure 4
Ethernet under SheepShaver. The first time you run SheepShaver, it
will ask you if you want to modify the
If you click the OK button, SheepShaver will automatically make the BeOS network configuration to support
modification; if you click the Cancel button, SheepShaver will disable Ethernet under SheepShaver.
Ethernet.

SheepShaver Settings
The SheepShaver Settings panel appears each time you launch
SheepShaver. You'll probably configure most of these settings once
and then leave them alone. In fact, many of them can simply be left at
their default values. Before you can use SheepShaver, though, you'll
have to visit the Volumes tab page. You'll probably want to tweak the settings on the Memory tab page as well.
Volumes Settings The Volumes tab lets you select which MacOS volumes you want to appear on the Mac Desktop in
SheepShaver. Both HFS and HFS+ volumes are supported, as are removable volumes (Zip and Jaz cartridges, for
example). Note, however, that you have to mount all volumes--including removables--before you launch
SheepShaver. You can't mount a removable cartridge from within SheepShaver. This should be fixed in version 2.0.

Figure 5 Selecting Mac Volumes to Mount in SheepShaver When you first

From the Volumes tab page in launch SheepShaver, the Settings panel will open with the Volumes tab
SheepShaver's Settings panel, you can page displayed. Its list of volumes will be empty. To add a volume to the
select HFS and HFS+ volumes to be list, click the Add... button. A BeOS File panel will appear, from which
mounted on the Mac Desktop in you can select a volume. Repeat this process for each volume that you
SheepShaver. want SheepShaver to mount. Note that before you can mount a volume in
SheepShaver, you must first mount it in BeOS; Option+click on the BeOS
Desktop and choose Mount from the context menu.

Once you've added a volume to SheepShaver's list, go back and unmount

it from the BeOS Desktop before you launch SheepShaver. It's a pain, but
less of a pain than the alternative. As part of its startup process,
SheepShaver tries automatically to unmount from BeOS any volumes that
you've selected to appear in the MacOS. But this automatic process
doesn't always succeed. If it fails, chances are good that your Mac will
hang. If this occurs, the only way out is a manual restart.

While SheepShaver is running with HFS or HFS+ volumes mounted in its environment, do not attempt to
mount those same volumes in BeOS. Doing so can cause disk corruption and unrecoverable data loss. Never
click the "Mount all disks now" button in the Disk Mount Settings panel while SheepShaver is running!

To remove a volume from the SheepShaver volumes list, select the volume (you'll have to know its SCSI ID--the list
doesn't display volume names), then click the Remove button.

Selecting a SheepShaver Boot Volume The Boot From pop-up menu on this tab page lets you select a MacOS boot
volume. When Any (the default value) is selected, SheepShaver will boot from the first boot volume it finds. When
CD-ROM is selected, SheepShaver will attempt to boot from the disk in the CD-ROM drive.

Disabling SheepShaver's CD-ROM Driver SheepShaver includes a CD-ROM driver that should work for all CD-
ROMs that shipped with MacOS systems supported by the BeOS. The SheepShaver CD-ROM driver supercedes
whatever CD-ROM driver is installed in your MacOS System Folder (typically Apple CD-ROM or CD-ROM
Toolkit). The Disable CD-ROM Driver checkbox on the Volumes tab page gives you a way to disable SheepShaver's
CD-ROM driver. But since there's no other CD-ROM driver that works with SheepShaver, checking this box will
disable your CD-ROM drive.
 In most cases, you'll have no need to disable the CD-ROM driver. An exception: Disabling the driver will
enable you to play audio CDs in BeOS while working in SheepShaver.

Graphics Settings SheepShaver provides two display Figure 6

modes: window and full-screen (see Display Modes, The SheepShaver Graphics Settings tab page provides
below, for more details). The Graphics settings tab page partial control over how the MacOS environment is
allows you to control the refresh rate of the SheepShaver displayed.
window when SheepShaver is in window mode. It also
allows you to turn off graphics acceleration. Other
graphics-display settings, such as screen resolution, must
be set from within SheepShaver itself.

Setting SheepShaver's Window Refresh

Rate SheepShaver runs much more efficiently in full-
screen mode. Performance and responsiveness are both far
better in full-screen mode than in window mode. If,
however, you decide to use it in window mode (and you
have no choice if you haven't paid the shareware fee), you
can change SheepShaver's refresh rate from the Window
Refresh Rate pop-up menu on the Graphics Settings tab page. But there's not much point. Although it's
counterintuitive, higher refresh rates make SheepShaver behave more slowly, because it's spending its time drawing
the contents of the SheepShaver window instead of running the MacOS. So stick with the default rate (which is
around 5 or 6 Hz). Note that this refresh rate refers only to how frequently the MacOS environment inside the
SheepShaver window is redrawn. Everything else in BeOS will continue to be refreshed at the rate set in the Screen
preferences panel, which will probably be in the 65-75 Hz range.

Figure 7 Disabling QuickDraw Acceleration SheepShaver can take advantage of

Users running SheepShaver on a Mac most of the BeOS graphics drivers for graphics cards supported by BeOS
have no need to alter these serial port for PowerPC. These drivers provide QuickDraw acceleration.
settings. Accordingly, the QuickDraw Acceleration checkbox on the Graphics
Settings tab page is selected by default. There's not likely to be any reason
why you'd want to turn off QuickDraw acceleration, since it speeds up
graphics display, but if you suspect that the driver for your graphics card
may be causing a problem, you might want to try deselecting this option.

Serial Ports Settings These settings are here for people running
SheepShaver on a BeBox. If you're running it on a MacOS system, you
shouldn't need to change anything on this tab page.

Network Settings The Network Settings tab page presents you with the
option to disable Ethernet. By default, this checkbox is unselected; that is,
 Ethernet is Figure 8
enabled. In If your Mac has no Ethernet interface, select this
most cases, checkbox. Otherwise, leave it unselected.
you'll want to
leave it that
way. If,
however, your
Mac has no
Ethernet
capability,
you'll probably
want to select the Disable Ethernet option. Otherwise,
every time you start up SheepShaver, you'll get a warning
that there's a problem with your Ethernet connection. You'd
think that software that's clever enough to allow one
operating system to pretend to be another one would also be clever enough to figure out that a particular machine has
no Ethernet interface, but apparently that's not the case.

Memory Settings
SheepShaver's Memory Settings tab page is where you Figure 9
establish how much memory will be available to the The SheepShaver Memory Settings tab page lets you
SheepShaver MacOS environment. Setting this memory establish the amount of memory that will be available
allocation is simple: You just move a slider. Understanding in the SheepShaver Mac OS environment.
what's going on, however, is a bit trickier.

BeOS has a fully functional demand-paged virtual memory

(VM) system that is always enabled (see Chapter 9,
Preferences, for details). It is part of the core OS. The
MacOS, in contrast, has a suboptimal virtual memory
system that is bolted onto the OS. The two VMs don't get
along well. Hence the warning in the Launching
SheepShaver section, above, to turn off the MacOS's
virtual memory system before running SheepShaver.
Although Apple generally recommends that you turn
virtual memory on in the MacOS, you'll have nothing but
trouble (and, in fact, you probably won't be able to launch SheepShaver without crashing) if you don't turn it off.

One of the advantages to Mac users of the MacOS's virtual memory is that when it is turned on, it enables applications
to run in less memory than when it is turned off. You've probably noticed the messages in the Get Info windows of
Mac applications that, when virtual memory is on, tell you how much more memory will be needed by the application
if you turn virtual memory off. So when setting the RAM size for SheepShaver, remember that if you want to run
several Mac applications at once, and you normally run the MacOS with virtual memory on, you're going to need
more memory than you're used to needing for those apps. Fortunately, BeOS's virtual memory system is quite up to
the task.

The minimum RAM size that you can set for SheepShaver is 8MB. You'll probably want significantly more, though.
You wouldn't try to run a Mac with only 8MB of RAM (and virtual memory off, remember)--especially not if you
wanted to use any Microsoft applications--so it doesn't make sense to run SheepShaver that way, either.

The maximum amount of memory you can allocate for SheepShaver depends on how you have BeOS virtual memory
set up in the Virtual Memory preferences panel. When you run BeOS, it creates a swap file. The swap file's minimum
size depends on how much physical RAM is installed in your computer, but it will be at least 48MB. If there is room
available on your BeOS hard disk, you can set the swap file size to be much larger.

What shows up on the SheepShaver Memory Settings tab page as the maximum amount of RAM available for
SheepShaver is equal to the size of your BeOS swap file minus 8MB. In the Figure 09, for example, the BeOS swap
file is 256MB, so the maximum RAM that can be allocated to SheepShaver is 248MB.

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