<s>
A	O
fast	B-Device
loader	I-Device
is	O
a	O
software	O
program	O
for	O
a	O
home	O
computer	O
,	O
such	O
as	O
the	O
Commodore	O
64	O
or	O
ZX	B-Operating_System
Spectrum	I-Operating_System
,	O
that	O
accelerates	O
the	O
speed	O
of	O
file	O
loading	O
from	O
floppy	B-Device
disk	I-Device
or	O
compact	B-Device
cassette	I-Device
.	O
</s>
<s>
Fast	B-Device
loaders	I-Device
came	O
about	O
because	O
of	O
a	O
discrepancy	O
between	O
the	O
actual	O
speed	O
at	O
which	O
floppy	B-Device
drives	I-Device
could	O
transfer	O
data	O
and	O
the	O
speed	O
that	O
was	O
provided	O
by	O
the	O
operating	B-General_Concept
system	I-General_Concept
's	O
default	O
routines	O
.	O
</s>
<s>
This	O
discrepancy	O
was	O
most	O
pronounced	O
on	O
the	O
VIC-20	B-Device
and	O
Commodore	O
64	O
.	O
</s>
<s>
While	O
the	O
earlier	O
Commodore	B-Device
PET	I-Device
series	O
had	O
used	O
an	O
industry-standard	O
IEEE-488	O
parallel	B-Device
bus	I-Device
,	O
this	O
was	O
replaced	O
with	O
a	O
custom	B-Protocol
Commodore	I-Protocol
serial	B-Protocol
bus	I-Protocol
on	O
the	O
VIC-20	B-Device
.	O
</s>
<s>
The	O
serial	B-Protocol
bus	I-Protocol
was	O
intended	O
to	O
be	O
nearly	O
as	O
fast	O
as	O
its	O
predecessor	O
,	O
due	O
to	O
the	O
use	O
of	O
the	O
6522	B-Device
VIA	I-Device
as	O
a	O
hardware	O
shift	B-General_Concept
register	I-General_Concept
on	O
both	O
the	O
drive	O
and	O
computer	O
.	O
</s>
<s>
However	O
,	O
hardware	O
bugs	O
were	O
discovered	O
in	O
the	O
6522	B-Device
that	O
prevented	O
this	O
function	O
from	O
working	O
consistently	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
KERNAL	B-Operating_System
ROM	B-Device
routines	O
were	O
hastily	O
rewritten	O
to	O
transfer	O
a	O
single	O
bit	O
at	O
a	O
time	O
,	O
using	O
a	O
slow	O
software	O
handshaking	B-Protocol
protocol	O
.	O
</s>
<s>
Although	O
the	O
C64	O
replaced	O
the	O
6522	B-Device
VIA	I-Device
with	O
two	O
6526	B-Device
CIA	I-Device
chips	O
,	O
which	O
did	O
not	O
suffer	O
from	O
this	O
bug	O
,	O
the	O
companion	O
1541	B-Device
disk	O
drive	O
still	O
had	O
a	O
6522	B-Device
VIA	I-Device
.	O
</s>
<s>
Commodore	O
chose	O
not	O
to	O
redesign	O
the	O
1541	B-Device
hardware	O
,	O
also	O
in	O
order	O
to	O
retain	O
backward	O
compatibility	O
with	O
VIC-20	B-Device
peripherals	O
;	O
this	O
however	O
came	O
at	O
the	O
expense	O
of	O
speed	O
.	O
</s>
<s>
Because	O
of	O
the	O
transfer	O
protocol	O
,	O
the	O
Commodore	B-Device
1540	I-Device
and	O
1541	B-Device
disk	O
drives	O
soon	O
gained	O
a	O
reputation	O
for	O
extreme	O
slowness	O
.	O
</s>
<s>
Only	O
at	O
the	O
introduction	O
of	O
the	O
Commodore	B-Device
128	I-Device
computer	O
and	O
the	O
Commodore	B-Device
1571	I-Device
disk	O
drive	O
was	O
the	O
original	O
plan	O
put	O
into	O
action	O
and	O
a	O
hardware	O
shift	B-General_Concept
register	I-General_Concept
was	O
used	O
,	O
reducing	O
the	O
need	O
for	O
special	O
fast	B-Device
loaders	I-Device
.	O
</s>
<s>
Soon	O
after	O
the	O
C64	O
's	O
release	O
,	O
some	O
astute	O
programmers	O
realized	O
that	O
Commodore	O
's	O
bit-banging	B-Algorithm
serial	O
KERNAL	B-Operating_System
routines	O
were	O
unnecessarily	O
sluggish	O
.	O
</s>
<s>
Since	O
the	O
CPU	B-General_Concept
in	O
the	O
C64	O
ran	O
at	O
approximately	O
the	O
same	O
speed	O
as	O
that	O
in	O
the	O
1541	B-Device
disk	O
drive	O
,	O
it	O
was	O
sufficient	O
to	O
synchronize	O
only	O
at	O
the	O
beginning	O
of	O
each	O
byte	B-Application
,	O
rather	O
than	O
at	O
each	O
individual	O
bit	O
.	O
</s>
<s>
Moreover	O
,	O
this	O
transfer	O
method	O
allowed	O
two	O
bits	O
to	O
be	O
sent	O
simultaneously	O
,	O
one	O
over	O
the	O
standard	O
DATA	O
line	O
and	O
one	O
over	O
the	O
CLK	O
line	O
(	O
which	O
was	O
normally	O
used	O
to	O
perform	O
the	O
handshaking	B-Protocol
)	O
.	O
</s>
<s>
On	O
the	O
C64	O
,	O
this	O
required	O
very	O
careful	O
timing	O
to	O
avoid	O
interference	O
from	O
interrupts	O
and	O
from	O
the	O
VIC-II	O
graphics	B-General_Concept
chip	I-General_Concept
,	O
which	O
could	O
"	O
steal	O
"	O
CPU	B-General_Concept
cycles	O
.	O
</s>
<s>
Some	O
fast	B-Device
loaders	I-Device
disabled	O
interrupts	O
and	O
blanked	O
the	O
screen	O
for	O
this	O
reason	O
.	O
</s>
<s>
A	O
fast	B-Device
loader	I-Device
would	O
generally	O
"	O
wedge	O
"	O
itself	O
into	O
the	O
LOAD	O
vector	B-General_Concept
at	O
$0330	O
,	O
thus	O
intercepting	O
any	O
calls	O
to	O
the	O
KERNAL	B-Operating_System
LOAD	O
routine	O
.	O
</s>
<s>
Next	O
,	O
the	O
fast	B-Device
loader	I-Device
would	O
transfer	O
the	O
necessary	O
code	O
into	O
the	O
drive	O
RAM	O
and	O
order	O
its	O
execution	O
,	O
then	O
receive	O
the	O
file	O
sent	O
by	O
the	O
altered	O
transfer	O
code	O
.	O
</s>
<s>
Various	O
software	O
companies	O
released	O
fast	B-Device
loaders	I-Device
for	O
the	O
C64	O
,	O
usually	O
in	O
cartridge	B-Protocol
form	O
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
probably	O
the	O
most	O
popular	O
such	O
cartridge	B-Protocol
was	O
the	O
Epyx	B-Application
FastLoad	I-Application
.	O
</s>
<s>
Most	O
fast	B-Device
loader	I-Device
cartridges	B-Protocol
also	O
incorporated	O
other	O
features	O
to	O
increase	O
ease	O
of	O
use	O
.	O
</s>
<s>
An	O
on-board	O
implementation	O
of	O
Commodore	O
's	O
DOS	B-Operating_System
Wedge	I-Operating_System
was	O
included	O
in	O
most	O
fast	B-Device
loader	I-Device
cartridges	B-Protocol
.	O
</s>
<s>
Machine	B-General_Concept
language	I-General_Concept
monitors	I-General_Concept
,	O
disk	B-Application
editors	I-Application
,	O
and	O
various	O
convenience	O
commands	O
for	O
Commodore	B-Language
BASIC	I-Language
were	O
also	O
common	O
additions	O
.	O
</s>
<s>
Some	O
fast	B-Device
loader	I-Device
cartridges	B-Protocol
were	O
very	O
sophisticated	O
,	O
incorporating	O
a	O
reset	B-Application
button	I-Application
,	O
"	O
freeze	O
"	O
capabilities	O
,	O
and	O
a	O
simple	O
onboard	O
GUI	B-Application
.	O
</s>
<s>
The	B-Device
Final	I-Device
Cartridge	I-Device
III	I-Device
was	O
perhaps	O
the	O
most	O
successful	O
of	O
this	O
genre	O
.	O
</s>
<s>
A	O
few	O
commercial	O
fast	B-Device
loaders	I-Device
,	O
most	O
notably	O
CMD	O
's	O
JiffyDOS	O
,	O
were	O
not	O
cartridge-driven	O
but	O
instead	O
replaced	O
the	O
KERNAL	B-Operating_System
ROM	B-Device
in	O
the	O
C64	O
and	O
the	O
DOS	O
ROM	B-Device
in	O
the	O
1541	B-Device
.	O
</s>
<s>
The	O
cartridge	B-Protocol
,	O
Action	O
Replay	O
MK6	O
RAM	O
loader	O
loads	O
a	O
202	O
block	O
program	O
in	O
around	O
9	O
seconds	O
.	O
</s>
<s>
Its	O
Warp	O
loader	O
is	O
25	O
times	O
faster	O
,	O
but	O
programs	O
can	O
only	O
be	O
loaded	O
with	O
a	O
loader	O
saved	O
to	O
disk	O
when	O
the	O
cartridge	B-Protocol
is	O
not	O
present	O
.	O
</s>
<s>
Whereas	O
the	O
ARMK6	O
fastloader	B-Device
was	O
compatible	O
with	O
most	O
software	O
,	O
The	B-Device
Final	I-Device
Cartridge	I-Device
III	I-Device
was	O
known	O
to	O
crash	O
often	O
,	O
so	O
programs	O
had	O
to	O
be	O
loaded	O
in	O
normal	O
C64	O
mode	O
,	O
deactivating	O
the	O
cartridge	B-Protocol
,	O
making	O
it	O
more	O
or	O
less	O
useless	O
.	O
</s>
<s>
This	O
way	O
,	O
the	O
user	O
benefited	O
from	O
the	O
fast	B-Device
loader	I-Device
without	O
having	O
to	O
buy	O
or	O
know	O
about	O
a	O
dedicated	O
fast-loader	O
product	O
.	O
</s>
<s>
published	O
TurboDisk	O
,	O
a	O
fast	B-Device
loader	I-Device
that	O
included	O
C64	O
and	O
VIC-20	B-Device
versions	O
.	O
</s>
<s>
It	O
was	O
printed	O
yet	O
again	O
in	O
August	O
1986	O
,	O
without	O
the	O
VIC-20	B-Device
version	O
,	O
but	O
with	O
several	O
accompanying	O
utilities	O
to	O
relocate	O
the	O
program	O
in	O
memory	O
and	O
to	O
create	O
auto-booting	O
software	O
that	O
took	O
advantage	O
of	O
TurboDisk'''s	O
speed	O
.	O
</s>
<s>
A	O
Commodore	B-Device
128	I-Device
version	O
was	O
also	O
included	O
for	O
those	O
C128	O
users	O
who	O
still	O
had	O
1541	B-Device
disk	O
drives.COMPUTE	O
!	O
</s>
<s>
'	O
s	O
Gazette	O
also	O
published	O
several	O
other	O
utilities	O
that	O
speed	O
up	O
C64-to-1541	O
communications	O
,	O
including	O
Turbo	O
Copy	O
(	O
a	O
4-minute	O
full-disk	O
copier	O
)	O
,	O
TurboSave	O
(	O
a	O
utility	O
that	O
accelerated	O
the	O
speed	O
of	O
disk	O
saves	O
)	O
and	O
Quick	O
!	O
</s>
<s>
(	O
another	O
fast	B-Device
loader	I-Device
)	O
.RUN	O
Magazine	O
published	O
Sizzle	O
!	O
</s>
<s>
in	O
December	O
1987	O
,	O
an	O
integrated	O
package	O
that	O
included	O
a	O
relocatable	O
fast	B-Device
loader	I-Device
with	O
autoboot	O
generation	O
capability.BYTE	O
published	O
Loader	O
,	O
a	O
machine-language	O
fast-loading	O
software	O
for	O
Apple	B-Operating_System
DOS	I-Operating_System
3.3	O
,	O
in	O
November	O
1983	O
.	O
</s>
<s>
The	O
type-in	O
fast	B-Device
loader	I-Device
fashion	O
continued	O
in	O
the	O
age	O
of	O
the	O
Internet	O
.	O
</s>
<s>
Krill	O
's	O
Loader	O
(	O
2009	O
)	O
and	O
Spindle	O
(	O
2013	O
)	O
are	O
two	O
examples	O
of	O
C64-to-1541	O
"	O
IRQ	B-General_Concept
loaders	O
"	O
,	O
fast	B-Device
loaders	I-Device
that	O
allow	O
programs	O
(	O
mainly	O
games	O
)	O
to	O
keep	O
their	O
own	O
IRQs	B-General_Concept
during	O
loading	O
.	O
</s>
<s>
The	O
built-in	O
routines	O
for	O
storing	O
and	O
reading	O
data	O
to	O
and	O
from	O
Compact	B-Device
Cassette	I-Device
tapes	I-Device
were	O
made	O
for	O
safe	O
storing	O
rather	O
than	O
speed	O
.	O
</s>
<s>
The	O
PET	O
Rabbit	O
was	O
one	O
such	O
program	O
for	O
the	O
PET	O
,	O
while	O
TurboTape	O
was	O
one	O
for	O
the	O
Commodore	B-Device
Datassette	I-Device
.	O
</s>
<s>
Speedlock	O
was	O
a	O
software	O
protection	O
system	O
used	O
on	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
and	O
the	O
Amstrad	B-Device
CPC	I-Device
,	O
written	O
by	O
David	O
Aubrey-Jones	O
and	O
David	O
Looker	O
in	O
1983	O
.	O
</s>
<s>
The	O
prototype	O
sat	O
unused	O
for	O
about	O
a	O
year	O
,	O
but	O
was	O
finally	O
picked	O
up	O
by	O
Ocean	O
Software	O
on	O
Daley	B-Application
Thompson	I-Application
's	I-Application
Decathlon	I-Application
,	O
released	O
in	O
late	O
1984	O
.	O
</s>
<s>
Speedlock	O
was	O
also	O
ported	O
to	O
the	O
Amstrad	B-Device
CPC	I-Device
in	O
1985	O
.	O
</s>
<s>
The	O
system	O
used	O
several	O
advanced	O
features	O
of	O
the	O
Spectrum	O
's	O
architecture	O
,	O
such	O
as	O
the	O
memory	O
refresh	O
register	O
and	O
parity	O
branch	O
instructions	O
of	O
the	O
Z80	B-General_Concept
processor	O
,	O
which	O
made	O
it	O
harder	O
to	O
create	O
illegitimate	O
copies	O
without	O
the	O
protection	O
.	O
</s>
<s>
Later	O
versions	O
did	O
not	O
include	O
this	O
,	O
but	O
instead	O
had	O
a	O
counter	O
showing	O
the	O
time	O
left	O
to	O
finish	O
loading	O
the	O
program	O
,	O
similar	O
to	O
those	O
of	O
Technician	B-Application
Ted	I-Application
and	O
Fairlight	B-Application
.	O
</s>
<s>
Some	O
companies	O
created	O
software	O
to	O
bypass	O
protection	O
schemes	O
,	O
including	O
Speedlock	O
,	O
for	O
the	O
purpose	O
of	O
backing	B-Protocol
up	I-Protocol
or	O
transferring	O
to	O
ZX	B-Device
Microdrive	I-Device
,	O
the	O
ZX	B-Operating_System
Spectrum	I-Operating_System
+3	O
,	O
or	O
other	O
proprietary	O
disk	O
systems.Invade-a-Load	O
was	O
a	O
fast	B-Device
loader	I-Device
for	O
cassette-based	O
games	O
which	O
not	O
only	O
accelerated	O
the	O
loading	O
of	O
blocks	O
from	O
the	O
tape	O
,	O
but	O
also	O
contained	O
a	O
mini-game	O
(	O
in	O
this	O
case	O
,	O
a	O
clone	O
of	O
Space	B-Application
Invaders	I-Application
)	O
that	O
could	O
be	O
played	O
while	O
waiting	O
for	O
the	O
main	O
game	O
to	O
finish	O
loading	O
.	O
</s>
<s>
It	O
mostly	O
appeared	O
in	O
games	O
sold	O
in	O
the	O
United	O
Kingdom	O
,	O
as	O
,	O
by	O
the	O
time	O
it	O
was	O
written	O
,	O
the	O
Commodore	O
market	O
in	O
the	O
United	O
States	O
had	O
mostly	O
switched	O
to	O
floppy	B-Device
disk	I-Device
media	O
.	O
</s>
<s>
The	O
loader	O
was	O
also	O
memorable	O
for	O
the	O
soundtrack	O
,	O
originally	O
made	O
by	O
Rob	O
Hubbard	O
for	O
the	O
Mastertronic	O
title	O
One	B-Application
Man	I-Application
and	I-Application
His	I-Application
Droid	I-Application
.	O
</s>
<s>
In	O
the	O
UK	O
,	O
where	O
the	O
price	O
of	O
a	O
1541	B-Device
disk	O
drive	O
was	O
beyond	O
the	O
means	O
of	O
many	O
of	O
the	O
target	O
audience	O
of	O
C64	O
owners	O
,	O
there	O
was	O
enormous	O
demand	O
for	O
fast	B-Device
loaders	I-Device
for	O
C64	O
games	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
to	O
use	O
such	O
a	O
loader	O
was	O
Llamasoft	O
where	O
Jeff	O
Minter	O
's	O
classic	O
Revenge	B-Application
of	I-Application
the	I-Application
Mutant	I-Application
Camels	I-Application
came	O
with	O
a	O
fast	O
loading	O
version	O
on	O
one	O
side	O
of	O
the	O
cassette	O
and	O
a	O
conventional	O
loading	O
version	O
on	O
the	O
other	O
.	O
</s>
<s>
Daley	B-Application
Thompson	I-Application
's	I-Application
Decathlon	I-Application
was	O
a	O
very	O
visible	O
example	O
of	O
this	O
.	O
</s>
<s>
In	O
1995	O
,	O
Yoichi	O
Hayashi	O
of	O
Namco	O
Ltd	O
.	O
invented	O
a	O
variant	O
of	O
the	O
Invade-a-Load	O
technique	O
for	O
use	O
with	O
optical	B-Device
disc	I-Device
based	O
platforms	O
such	O
as	O
PlayStation	B-Device
and	O
applied	O
for	O
a	O
patent	O
.	O
</s>
