2004.12_Bygone Battles-Emulating Legacy Computer Systems in Linux.pdf

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Retro-Gaming

Bygone Battles

Do you miss your trusty Sinclair Spectrum? Do you long for the Commodore you know only in your history books? Old

platforms come alive using the tools of the retro-gamers. BY IAN POINTER

tled on the IBM PC, there were

many different types of computers

with exotic-sounding names like Enter-

prise, Oric, Dragon, Electron, Spectrum,

and Amiga. Although these machines are

no longer with us, most of these legacy

systems sill have ardent fans that keep

their memory alive. These fans prefer the

simplicity of the older era – when pro-

grams had to fit inside tiny quantities of

memory and programmers had to use

every trick they could imagine to get the

most out of a computer – to the fast

processors and gigabytes storage of

today.

These enthusiasts are more common

than you might think; the coming of the

Internet has allowed people from all

across the world to reminisce about the

past, and for the last eight years, a Clas-

sic Gaming Expo ( http://www.cgexpo.

com ) has been held in America, with

exhibitions from big arcade firms like

Midway and Konami, plus lectures from

hardware geniuses such as Steve Woz-

niak, co-founder of Apple.

While purists will be satisfied with

nothing less than the real machines,

in many cases this is not practical or pos-

sible, and so the enthusiasts started

writing programs called emulators ,

which allow old computers to be simu-

lated on today’s hardware. These

programs often go beyond the original’s

capabilities, for example allowing the

state of the computer to be saved for

later use (useful when playing games),

or providing the ability to communicate

with other copies of the emulator over

the Internet.

This article will explain where to

obtain some of the more popular Linux-

based emulators (starting with the early

8-bit systems then moving on to 16-bit

computers and consoles),where to get

software to run on them, and how you

can even use Linux to develop new pro-

grams for these old computers.

found at http://www.libsdl.org . It is

probably best to download the source

and build it manually, so you can be sure

it doesn’t use older graphics systems like

svgalib .

Fuse emulates all the major revisions

of the Spectrum, including the American

Timex versions plus some of the Russian

clones. It also has a method of recording

applications you are using for later play-

back, so you can send proof that you

have completed Jet Set Willy to all your

friends. The interface is a little esoteric;

the menu system within the emulator is

custom built and accessed via the func-

tion keys. This makes reading the

accompanying documentation almost

essential, although for most cases, press-

ing F1, ‘F’ for File, and ‘O’ to load a

Spectrum image file will be enough to

get by.

World of Spectrum [1] is a repository

for Sinclair information, and it contains

scans of magazines and copies of the

manuals, as well as thousands of games

and other software. Five games that are

worth seeking out are: 3D Deathchase,

Sinclair Spectrum

The Spectrum, released in 1982, was the

most popular home computer in the UK,

and it is fondly remembered for its

strange rubber keyboard. Despite its lim-

ited color and sound abilities, it built up

an impressive software library, compris-

ing thousands of games and other types

of applications. It went through multiple

revisions, starting with the humble origi-

nal with 16 Kilobytes of RAM, to a

version with a 3” inch disk drive, a

proper keyboard, an improved sound

chip, and 128 Kilobytes of RAM. The

Spectrum also flourished in the Soviet

Union; the plans for the machine were

smuggled across the Iron Curtain, lead-

ing to the production of many illegal

clones.

Fuse is a Spectrum emulator for Linux

that can be found at http://fuse-

emulator.sourceforge.net . Like all the

emulators in this article, it works best

with the SDL libraries, which can be

December 2004

www.linux-magazine.com

Emulating Legacy Game Platforms

B efore the computer industry set-

Retro-Gaming

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Jet Set Willy (seen in Figure 1), Dan Dare

III, Robocop, and Chaos.

into the 16-bit era. It was popular with

filmmakers due to a hardware add-on

called the Video Toaster, which allowed

the Amiga to mix digital effects with

video, and was used to generate some of

the special effects for TV series such as

SeaQuest DSV and Babylon 5.

There were many different versions of

the Amiga, from the original Amiga 1000

in 1985, the more common Amiga 500

model, and even ending up as the

insides of a CD-ROM based console, the

unsuccessful CD-32. The Amiga is some-

thing of a survivor, with a committed

user base that has stuck by it as it was

passed from company to compnay fol-

lowing the collapse of Commodore in

1994. The Amiga is now owned by the

Amiga Corporation, which is trying to

market the technology for use in mobile

devices.

A Linux emulator called Unix Amiga

Emulator (UAE) has existed for several

years, but for the past year, development

has focussed on the Windows port, Win-

UAE, and the original version has been

neglected. Richard Drummond forked

the orignal codebase, and maintains

what he calls Experimental UAE at

http://www.rcdrummond.net/uae , which

incorporates many of the recent addi-

tions to WinUAE.

Unfortunately, you can’t just down-

load the emulator and expect it to work

straightaway. The Amiga stored part of

its operating system on a ROM chip

known as Kickstart, and EUAE requires a

copy of this ROM. While the Spectrum

and C64 ROM images have been released

for free distribution, the Amiga ROM is

the property of Amiga Corporation and is

still protected by copyright laws. You

can, however, buy a copy of the Kickstart

ROMs from the Amiga Forever website

[3], at the price of $29.99.

Commodore 64

While the Spectrum was the computer of

the UK and Russia, in the rest of the

world the Commodore 64 was the most

popular 8-bit system. For its time, it had

wonderful graphics, a proper keyboard,

and a sound chip that still sounds

impressive today. Over ten thousand

applications were released for it during

its lifespan, and the addition of a disk

drive meant that it had more ambitious

applications than the Spectrum, for

example GEOS, a primitive GUI window-

ing system.

There are several C64 emulators for

Linux, but the most comprehensive is

VICE ( http://www.viceteam.org ). Not

only does VICE emulate the C64, but it

also includes emulators to run the PET,

VIC-20, C-16, the Plus/4, and the C128

machines as well, which is almost every

Commodore machine up until the

release of the Amiga.

VICE can record snapshots for later

playback, and it also allows the video

and audio streams to be recorded in

MPEG form, as long as the ffmpeg library

is present. The user interface is rather

confusing; menus are accessed via hold-

ing the left or right mouse buttons, and

you must select the item before releasing

the button.

There are also some installation

issues; I built VICE from source and used

make install as usual, but when running

the emulator, I found I couldn’t type any-

thing on the C64 screen. It turned out

that I needed to set a keymap file indi-

vidually via the right-mouse button

menu. Apart from those glitches, VICE is

a very good emulator.

For C64 games, C64.com [2] is a good

resource. It isn’t as thorough as World of

Spectrum, but it contains most of the

best games available for the system. The

site has downloads available as tape and

disk images. From this archive, five rec-

ommended games are: International

Karate +, Little Computer People, Wiz-

ball, California Games, and Impossible

Mission (shown in Figure 2).

Figure 2: Impossible Mission on VICE.

EUAE is rather complex to use; it has

the standard GTK library for its user

interface, but because there are so many

different varieties of Amiga, each of

which can have different amounts of

hard drives, disk drives, and even types

of memory, the emulator has an over-

whelming amount of options available.

However, for most games, the standard

options will suffice.

Like the ROM, most Amiga games are

not freely available, but certain compa-

nies have given permission for their

games to be distributed at no charge. You

will find several at the Amiga In A Box

website [4]. Another good resource is

Aminet [5], which contains a vast array

of public domain/shareware/GPL games

and utilities. Commercial games you

should try and seek out are Sensible Soc-

cer (shown in Figure 3), Midwinter,

Cannon Fodder, Formula 1 Grand Prix,

and Gravity Power.

Atari ST

Atari’s answer to the Amiga was the ST,

a similar machine in some respects as it

used the same CPU, but it lacked the

Amiga’s custom-built sound and graph-

ics chips. However, a dedicated MIDI

interface on the machine made the ST

the system of choice of musicians

around the world. Like the Amiga, it

went through several revisions, eventu-

ally metamorphosing into the Atari

Falcon, an ill-fated machine that would

be the last Atari computer.

Hatari, found at http://hatari.

sourceforge.net , is an ST emulator for

Linux. It is in the beginning stages of

development, but although it isn’t com-

plete, it is advanced enough to run many

programs.

Commodore Amiga

The Amiga furthered Commodore’s rep-

utation for making impressive computers

Figure 1: Jet Set Willy running on FUSE.

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Retro-Gaming

Like the Amiga, the ST had its operat-

ing system stored on a ROM chip, and

again this isn’t freely available. To get

around this, Hatari includes a free re-

implementation of the ROM that uses

none of Atari’s code, so it doesn’t need

any more files (although you can supply

a proper ST ROM image if you have one).

Again, this emulator uses a custom

menu system, accessed by pressing F12.

Although the ST also came in many fla-

vors, Hatari’s menus are easy-to-follow

and straight-forward to use.

Little Green Desktops [6] contains

links to public domain and shareware ST

games, while the Cinemaware site

( http://www.cinemaware.com ) has a

Vault section where its old ST games are

available for free download. Also, the

Dungeon Master Encyclopaedia page

( http://dmweb.free.fr/FTLGames.htm )

contains Amiga and ST versions of Dun-

geon Master that can be downloaded.

Apart from Dungeon Master, interesting

games to find are Populous, Carrier Com-

mand, Stunt Car Race, and Oids (shown

in Figure 4).

find Gens at http://gens.consolemul.com .

However, every attempt I made at load-

ing a game caused a crash on my Fedora

Core 2 machine. I found another emula-

tor, Generator ( http://www.squish.net/

generator ), with fewer features and no

32X/Mega-CD support, that could load

games without crashing. It is basic, but it

runs games at a reasonable speed. I

would recommend trying Gens to see if it

works, since it claims a higher compati-

bility rate and more complete emulation

than Generator.

It is very hard to find legal games for

the consoles. Many titles are being re-

released for newer systems like the

Playstation, and so the games companies

are very protective of their intellectual

property. Some public domain games

can be found at Zophar’s Domain [7], a

general emulation site. Figure 5 shows

Generator playing Moonwalker, an

action game based around Michael Jack-

son’s film of the same name. Other

interesting games include: Sonic, Mortal

Kombat, Strider, and Gunstar Heroes.

Figure 5: The Generator emulator running Moon-

walker.

emulates most of the SNES’s features,

including the Super FX chip, which

appeared in later games like Super

Stunt Race FX and the SNES version of

Doom. It also includes an option for hav-

ing multiple players playing the same

game over the Internet, which opens up

game playing possibilities that never

existed on the real console. The Linux

version of ZSNES can be found at http://

ipherswipsite.com/zsnes .

As with the Megadrive, the ROM

images of game cartridges are not avail-

able to legally download. Again,

however, there are several public domain

games for downloading on Zophar.

SNES

The SNES was the other major 16-bit

console. Although it was second in pop-

ularity to the Megadrive, its specialized

graphics and sound chips meant that

there were many impressive titles avail-

able for the system, like F-Zero, Chrono

Trigger, Starfox, Super Streetfighter 2,

and Super Mario World (shown in Figure

6). Unlike the Megadrive, there were no

add-on improvements to the original

hardware; Sony and Nintendo worked

together on a CD-ROM add-on, but the

companies fell out, and Sony took their

side of the project and re-made it as the

Playstation.

ZSNES is a Windows SNES emulator

that has been around for several years

now, and it has been ported to Linux. It

Genesis

The Sega Megadrive (known as the Gen-

esis in America) was the first and most

popular 16-bit console. With its mascot

Sonic The Hedgehog, it ran rings around

Nintendo’s graphically superior SNES.

The system also sported a number of

add-ons in its later years, including a CD

drive called the Mega-CD, which brought

full-motion video and the huge capacity

of CDs to the console, and the 32X,

which provided an upgrade to the graph-

ics and CPU subsystems so the

Megadrive could run complex 3D games

like Virtua Racing and Star Wars Arcade.

Gens is a Megadrive emulator that

says it can run 32X and MegaCD games

in addition to standard ones. You can

Development

Even though these machines are no

longer made (except for the Amiga), all

of them still have thriving development

communites. Even the Spectrum and

Commodore 64 have programmers dedi-

cated to squeezing the last drop of

performance from their aging graphics

and sound capabilities, producing fabu-

lous animations known as demos. Some

of the best of these can be found at

http://www.c64.ch and http://www.

zxdemo.org .

The advent of emulators means

that you no longer need to own the ori-

ginal machine to write for them;

everything can be written on a current

machine and then tested in the emulator.

The Amiga and ST have ports of GCC

available, but if you want to program for

the consoles or the 8-bit systems, you

will have to delve into assembler pro-

gramming.

Each machine uses a different CPU, so

you’ll have to learn different types of

assembler for each one, as well as dis-

Figure 3: EUAE running Sensible Soccer.

Figure 4: Oids on the Hatari emulator.

December 2004

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Retro-Gaming

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covering how to drive the custom chips.

Thankfully, the Internet has collected

most of the information, turning this

from an impossible task into a merely

hard one. Programmer’s Heaven con-

tains guides for lots of different systems,

and USENET groups like comp.sys.

sinclair can offer help for people wishing

to program old systems.

While retro-programming

is mostly done for love,

there are a few companies

that actually make some

money out of it. For exam-

ple, various firms make

money selling cartridges of

new Atari 2600 games at

Atari Age ( http://www.

atariage.com/store/index.

php ).

most of the activity in the retro scene. As

you can imagine, many more emulators

are available for Linux. If you go to

http://linuxemu.retrofaction.com , you

will find many links to other emulators,

from gaming systems like the NeoGeo

Pocket, to more historical projects, such

as an emulator for the famous 1949 Man-

chester Baby.

■

Ian Pointer is a Com-

puter Science

graduate from the

University of Man-

chester. He grew up

with a Spectrum 48K,

until it melted after a

16-hour gaming

marathon. These days, he's upgraded to

a Linux box.

INFO

[1] World of Spectrum:

http://www.worldofspectrum.org

[2] C64.com:

http://wwww.64.com

[3] Amiga Forever:

http://www.amigaforever.com

[4] Amiga In A Box:

http://aiab.emuunlim.com

[5] Aminet:

http://wuarchive.wustl.edu/~aminet

[6] Little Green Desktops:

http://www.atari.st

[7] Zophar’s Domain

[8] Programmer’s Heaven:

http://www.programmersheaven.com/

zone8/index.htm

Conclusion

Hopefully this article has

introduced you to the world

of emulation. The emphasis

has been on old games,

since this is the source of

Figure 6: Super Mario World on ZSNES.

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