Fast loader
A fast loader is a software program for a home computer, such as the Commodore 64 or ZX Spectrum, that accelerates the speed of file loading from floppy disk or compact cassette.
The serial bus was intended to be nearly as fast as its predecessor, due to the use of the 6522 VIA as a hardware shift register on both the drive and computer.
As a result, the KERNAL ROM routines were hastily rewritten to transfer a single bit at a time, using a slow software handshaking protocol.
Commodore chose not to redesign the 1541 hardware, also in order to retain backward compatibility with VIC-20 peripherals; this however came at the expense of speed.
Soon after the C64's release, some astute programmers realized that Commodore's bit-banging serial KERNAL routines were unnecessarily sluggish.
Since the CPU in the C64 ran at approximately the same speed as that in the 1541 disk drive, it was sufficient to synchronize only at the beginning of each byte, rather than at each individual bit.
On the C64, this required very careful timing to avoid interference from interrupts and from the VIC-II graphics chip, which could "steal" CPU cycles.
Machine language monitors, disk editors, and various convenience commands for Commodore BASIC were also common additions.
Some fast loader cartridges were very sophisticated, incorporating a reset button, "freeze" capabilities, and a simple onboard GUI.
[2][3][4][5] It was printed yet again in August 1986, without the VIC-20 version, but with several accompanying utilities to relocate the program in memory and to create auto-booting software that took advantage of TurboDisk's speed.
The prototype sat unused for about a year, but was finally picked up by Ocean Software on Daley Thompson's Decathlon, released in late 1984.
The system used several advanced features of the Spectrum's architecture, such as the memory refresh register and parity branch instructions of the Z80 processor, which made it harder to create illegitimate copies without the protection.
Later versions did not include this, but instead had a counter showing the time left to finish loading the program, similar to those of Technician Ted and Fairlight.
The loader was also memorable for the soundtrack, originally made by Rob Hubbard for the Mastertronic title One Man and His Droid.
In the UK, where the price of a 1541 disk drive was beyond the means of many of the target audience of C64 owners, there was enormous demand for fast loaders for C64 games.
U.S. Gold releases became infamous for playing the U.S. National Anthem and showing a character map version of the Stars and Stripes as their games loaded.
In 1995, Yoichi Hayashi of Namco Ltd. invented a variant of the Invade-a-Load technique for use with optical disc based platforms such as PlayStation and applied for a patent.
