OTHER THAN THE EMULATOR, you usually need two things: some
ROMs and a BIOS. “ROM” is a blanket term for programs you want
to emulate. Although it should refer to an image of a system’s
Read Only Memory chip, it is often used in the context of normal
disk images that can be altered. Either way, you search for ROMs
on specialist ROM sites. The BIOS is another blanket term for the
program responsible for controlling the machine.
Distributing ROMs is generally illegal, unless there’s a license
that allows it—the exact legality varies between territories.
Dumped copies of a system BIOS are legal under US law as long
as the user owns the original machine. As you will see later, some
emulators have their own substitute BIOS, which anyone can use
legally and for free, developed through a process of reverse-
engineering, though usually at a cost of emulation accuracy.SOME WINE?
If you’ve used Linux for any decent length of time, you’ll have come
across Wine. Wine lets you run Windows programs on Linux,
but as any smarty-pants will tell you, Wine stands for “Wine Is
Not an Emulator.” So what is it, then? Wine is what’s known as a
compatibility layer. Compatibility layers take system calls from
the foreign application and translate them for the native system.
For instance, if you’re running Microsoft Paint and click the
maximize button, it sends a signal to the OS (a system call)
to maximize the window. If you were running Paint in Linux with
Wine, when you click the maximize button, Wine simply takes that
Windows system call and substitutes it with a Linux system call.
The result is that rather than running a program under a
Windows emulator, you are running the program natively as
a Linux application—the main benefit being speed. Compatibility
layers don’t stop there. Another variant is what’s known as a
wrapper, which translates one kind of driver API into another.
For instance, in the late 1990s, 3dfx Voodoo cards were
extremely popular for 3D acceleration. Although these cardssupported OpenGL and Microsoft’s Direct3D, 3dfx had its own
proprietary Glide API that would guarantee the best performance
with its hardware. This is often called a wrapper.
With its deep pockets, Valve was able to build upon the
existing Wine codebase with its own functionality. By changing
from OpenGL to the new Vulkan API, Valve implemented huge
performance gains, making conversion between Microsoft
DirectX 12 and the Linux desktop genuinely viable. Although
it’s still relatively early days, around 53 percent of Windows
games work so far, giving Linux gamers an enormously
increased library.EMULATION BASICS
What’s inside the box? Another box...
The Raspberry Pi’s power and diminutive size made it an instant hit
on the emulator scene—a Pi Zero even fits inside a NES controller.Emulators: Software running inside hardware running on
software—it’s like Inception for computers!MAME AND GAME
It would be remiss of us not to mention the colossus that
is MAME—the Multiple Arcade Machine Emulator. The
hardware of older arcade machines could vary wildly
between games, so an emulator was needed that covered
all these different machines.
MAME differs from other emulators in that it uses a
modular approach, where individual cores are installed
that power and control different machines. This approach
is an effective new path that may prove more reliable than
constantly writing new emulators with different interfaces.
MAME has been around since the 1990s, and is
command-line driven, so you’ll want a GUI front end for
it; MESS has been on the scene for ages, but RetroArch is
now the most popular.
RetroArch is probably in your Linux distro’s repository,
but if not, check the instructions at http://www.retroarch.com
for multiple installer options. To save time and avoid
frustration, choose the Development version over Stable.
If you choose the Stable version, you may not have the Core
Updater function, which is where you can choose from a
large list of regularly updated emulation cores.
However, not everyone is a fan of RetroArch—it can
require a lot of tinkering, and may mess with your control
layouts. If you fancy an alternative, try Attract-Mode (http://
attractmode.org)—it’s a newer front end that is still open
source, but has a strong community behind it, and support
for scripting.maximumpc.com JUN 2019 MAXIMUMPC 25