Fast loader
Encyclopedia
A fast loader is a software program for a home computer
- most commonly, the Commodore 64
- that accelerates the speed of file loading from the floppy disk
drive.
's default routines. This discrepancy was most pronounced on the Commodore VIC-20
and 64
. While the earlier Commodore PET
series had used an industry-standard IEEE-488
parallel bus
, this was replaced with a custom serial bus on the VIC-20. 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. However, hardware bugs were discovered in the 6522 that prevented this function from working consistently. As a result, the KERNAL
ROM
routines were hastily rewritten to transfer a single bit at a time, using a slow software handshaking
protocol.
Although the C64 replaced the 6522 VIA with two 6526 CIA
chips, which did not suffer from this bug, the companion 1541
disk drive still had a 6522 VIA. 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. Because of the transfer protocol, the Commodore 1540
and 1541
disk drives soon gained a reputation for extreme slowness. Only at the introduction of the Commodore 128
computer and the Commodore 1571
disk drive was the original plan put into action and a hardware shift register was used, reducing the need for special fast loaders.
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
. Moreover, this transfer method allowed two bits to be sent simultaneously, one over the standard
graphics chip
, which could "steal" CPU cycles. Some fast loaders disabled interrupts and blanked the screen for this reason. A fast loader would generally "wedge" itself into the
at
This technique was used for a few of the many fast-load systems made (such as JiffyDOS). Others were simply more efficient in I/O and file handling, offering marginal to good improvement. Other products added parallel hardware.
, probably the most popular such cartridge was the Epyx FastLoad
. Most fast loader cartridges also incorporated other features to increase ease of use. An on-board implementation of Commodore's DOS Wedge
was included in most fast loader cartridges. Machine language monitors, disk editor
s, 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
. The Final Cartridge III
was perhaps the most successful of this genre. A few commercial fast loaders, most notably CMD's
JiffyDOS, were not cartridge-driven but instead replaced the KERNAL
ROM
in the C64 and the DOS ROM in the 1541. While these were more difficult to install, they offered greatly increased compatibility, being almost invisible to software running on the machine.
The cartridge, Action Replay MK6 RAM loader loads a 202 Block program in around 9 seconds. Its Warp loader is 25 times faster. (Programs can only be loaded with a loader saved to disk when cartridge it not present)
Whereas the ARMK6 fastloader were compatible with most software, the TFC III were known to crash often, so you had to load a program in normal C64 mode, deactivating the cartridge, making it more or less useless.
Many commercial programs for the C64, especially games, contained their own fast-loading routines on the distribution media. The user would load a small "stub" program from the disk with the standard slow routines, which would then install faster transfer routines in both the computer and the drive before proceeding to load the rest of the program at high speed. This way, the user benefited from the fast loader without having to buy or know about a dedicated fast-loader product.
fast loading software. In April 1985, COMPUTE!
published TurboDisk, a fast loader that included C64 and VIC-20 versions. This program proved popular and was republished in the July 1985 issue of COMPUTE!'s Gazette
.
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 TurboDisks speed. A Commodore 128
version was also included for those C128 users who still had 1541 disk drives.
COMPUTE!'s Gazette also published several other utilities that speeded up C64-to-1541 communications, including Turbo Copy (a 4-minute full-disk copier), TurboSave (a utility that accelerated the speed of disk saves) and Quick! (another fast loader).
RUN Magazine published Sizzle! in December 1987, an integrated package that included a relocatable fast loader with autoboot generation capability.
Home computer
Home computers were a class of microcomputers entering the market in 1977, and becoming increasingly common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user...
- most commonly, the Commodore 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...
- that accelerates the speed of file loading from the floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
drive.
Background
Fast loaders came about because of a discrepancy between the actual speed at which floppy drives could transfer data and the speed that was provided by the operating systemOperating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
's default routines. This discrepancy was most pronounced on the Commodore VIC-20
Commodore VIC-20
The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...
and 64
Commodore 64
The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...
. While the earlier Commodore PET
Commodore PET
The Commodore PET was a home/personal computer produced from 1977 by Commodore International...
series had used an industry-standard IEEE-488
IEEE-488
IEEE-488 is a short-range digital communications bus specification. It was created for use with automated test equipment in the late 1960s, and is still in use for that purpose. IEEE-488 was created as HP-IB , and is commonly called GPIB...
parallel bus
Parallel port
A parallel port is a type of interface found on computers for connecting various peripherals. In computing, a parallel port is a parallel communication physical interface. It is also known as a printer port or Centronics port...
, this was replaced with a custom serial bus on the VIC-20. The serial bus was intended to be nearly as fast as its predecessor, due to the use of the 6522 VIA
MOS Technology 6522
The 6522 Versatile Interface Adapter was an integrated circuit made by MOS Technology, as well as second sources including Rockwell and Synertek. It served as a I/O port controller for the 6502 family of microprocessors, providing the parallel I/O capabilities of the PIA as well as timers and a...
as a hardware shift register
Shift register
In digital circuits, a shift register is a cascade of flip flops, sharing the same clock, which has the output of any one but the last flip-flop connected to the "data" input of the next one in the chain, resulting in a circuit that shifts by one position the one-dimensional "bit array" stored in...
on both the drive and computer. However, hardware bugs were discovered in the 6522 that prevented this function from working consistently. As a result, the KERNAL
KERNAL
The KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, followed by the extended but strongly related versions used in its successors; the VIC-20, Commodore 64, Plus/4, C16, and C128...
ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
routines were hastily rewritten to transfer a single bit at a time, using a slow software handshaking
Handshaking
In information technology, telecommunications, and related fields, handshaking is an automated process of negotiation that dynamically sets parameters of a communications channel established between two entities before normal communication over the channel begins...
protocol.
Although the C64 replaced the 6522 VIA with two 6526 CIA
MOS Technology CIA
The 6526/8520 Complex Interface Adapter was an integrated circuit made by MOS Technology. It served as a I/O port controller for the 6502 family of microprocessors, providing for parallel and serial I/O capabilities as well as timers and a Time-of-Day clock...
chips, which did not suffer from this bug, the companion 1541
Commodore 1541
The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...
disk drive still had a 6522 VIA. 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. Because of the transfer protocol, the Commodore 1540
Commodore 1540
The Commodore 1540 was the companion floppy disk drive for the Commodore VIC-20 home computer. It used single-sided 5¼" floppy disks, on which it stored roughly 170 KB of data utilizing Commodore's GCR data encoding scheme.Because of the low price of both the VIC-20 and the 1540, this...
and 1541
Commodore 1541
The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...
disk drives soon gained a reputation for extreme slowness. Only at the introduction of the Commodore 128
Commodore 128
The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...
computer and the Commodore 1571
Commodore 1571
The Commodore 1571 was Commodore's high-end 5¼" floppy disk drive. With its double-sided drive mechanism, it had the ability to utilize double-sided, double-density floppy disks natively. This was in contrast to its predecessors, the 1541 and 1570, which could fully utilize such disks only if the...
disk drive was the original plan put into action and a hardware shift register was used, reducing the need for special fast loaders.
Development
Soon after the C64's release, some astute programmers realized that Commodore's bit-bangingBit-banging
Bit banging is a technique for serial communications using software instead of dedicated hardware. Software directly sets and samples the state of pins on the microcontroller, and is responsible for all parameters of the signal: timing, levels, synchronization, etc...
serial KERNAL routines were unnecessarily sluggish. Since the CPU
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
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
Byte
The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
, rather than at each individual bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
. Moreover, this transfer method allowed two bits to be sent simultaneously, one over the standard
DATA line and one over the CLK line (which was normally used to perform the handshaking). On the C64, this required very careful timing to avoid interference from interrupts and from the VIC-IIMOS Technology VIC-II
The VIC-II , specifically known as the MOS Technology 6567/8562/8564 , 6569/8565/8566 , is the microchip tasked with generating Y/C/composite video graphics and DRAM refresh signals in the Commodore 64 and C128 home computers.Succeeding MOS's original VIC , the VIC-II was one of the two chips...
graphics chip
Graphics processing unit
A graphics processing unit or GPU is a specialized circuit designed to rapidly manipulate and alter memory in such a way so as to accelerate the building of images in a frame buffer intended for output to a display...
, which could "steal" CPU cycles. Some fast loaders disabled interrupts and blanked the screen for this reason. A fast loader would generally "wedge" itself into the
LOAD vectorInterrupt vector
An interrupt vector is the memory address of an interrupt handler, or an index into an array called an interrupt vector table that contains the memory addresses of interrupt handlers...
at
$HexadecimalIn mathematics and computer science, hexadecimal is a positional numeral system with a radix, or base, of 16. It uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F to represent values ten to fifteen...
0330, thus intercepting any calls to the KERNAL LOAD routine. Next, the fast loader would transfer the necessary code into the drive RAM and order its execution, then receive the file sent by the altered transfer code. Depending on the exact nature of the routines used, the loading speed could be improved by as much as a factor of five.This technique was used for a few of the many fast-load systems made (such as JiffyDOS). Others were simply more efficient in I/O and file handling, offering marginal to good improvement. Other products added parallel hardware.
Commercial fast loaders
Various software companies released fast loaders for the C64, usually in cartridge form. In the United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, probably the most popular such cartridge was the Epyx FastLoad
Epyx FastLoad
The Epyx FastLoad is a floppy disk fast loader cartridge made by American software company Epyx in 1984 for the Commodore 64 home computer. It was programmed by Epyx employee Scott Nelson, who later designed the Epyx Vorpal fastloading system for the company's games.Epyx FastLoad allowed programs...
. Most fast loader cartridges also incorporated other features to increase ease of use. An on-board implementation of Commodore's DOS Wedge
DOS Wedge
The DOS Wedge was a popular piece of Commodore 64 system software. Written by Bob Fairbairn, it was included by Commodore on the 1541 disk drive Test/Demo Disk and also packaged with the C64 Macro Assembler...
was included in most fast loader cartridges. Machine language monitors, disk editor
Disk editor
A disk editor is a computer program that allows its user to read, edit, and write raw data on disk drives ; as such, they are sometimes called sector editors, since the read/write routines built into the electronics of most disk drives require to read/write data in...
s, and various convenience commands for Commodore BASIC
Commodore BASIC
Commodore BASIC, also known as PET BASIC, is the dialect of the BASIC programming language used in Commodore International's 8-bit home computer line, stretching from the PET of 1977 to the C128 of 1985...
were also common additions. Some fast loader cartridges were very sophisticated, incorporating a reset button
Reset button
In electronics and technology, a reset button is a button that can reset a device. On video game consoles, the reset button restarts the game, losing the player's unsaved progress. On personal computersOn IBM mainframes reset neither clears memory nor initiates an IPL., the reset button clears the...
, "freeze" capabilities, and a simple onboard GUI
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...
. The Final Cartridge III
The Final Cartridge III
The Final Cartridge III was a popular extension cartridge which was created for the Commodore 64 and Commodore 128, produced by Riska B.V. Home & Personal Computers...
was perhaps the most successful of this genre. A few commercial fast loaders, most notably CMD's
Creative Micro Designs
Creative Micro Designs is a computer technologies company which today sells PCs and related equipment, but which started out in 1987 selling self-designed firmware updates and hardware for the Commodore 64 and C128 8-bit home/personal computers....
JiffyDOS, were not cartridge-driven but instead replaced the KERNAL
KERNAL
The KERNAL is Commodore's name for the ROM-resident operating system core in its 8-bit home computers; from the original PET of 1977, followed by the extended but strongly related versions used in its successors; the VIC-20, Commodore 64, Plus/4, C16, and C128...
ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...
in the C64 and the DOS ROM in the 1541. While these were more difficult to install, they offered greatly increased compatibility, being almost invisible to software running on the machine.
The cartridge, Action Replay MK6 RAM loader loads a 202 Block program in around 9 seconds. Its Warp loader is 25 times faster. (Programs can only be loaded with a loader saved to disk when cartridge it not present)
Whereas the ARMK6 fastloader were compatible with most software, the TFC III were known to crash often, so you had to load a program in normal C64 mode, deactivating the cartridge, making it more or less useless.
Many commercial programs for the C64, especially games, contained their own fast-loading routines on the distribution media. The user would load a small "stub" program from the disk with the standard slow routines, which would then install faster transfer routines in both the computer and the drive before proceeding to load the rest of the program at high speed. This way, the user benefited from the fast loader without having to buy or know about a dedicated fast-loader product.
Type-in fast loaders
Several of the popular Commodore magazines published type-inType-in program
A type-in program, or just type-in, is a computer program listing printed in a computer magazine or book, meant to be typed in by the reader in order to run the program on a computer....
fast loading software. In April 1985, COMPUTE!
COMPUTE!
Compute! was an American computer magazine that was published from 1979 to 1994, though it can trace its origin to 1978 in Len Lindsay's PET Gazette, one of the first magazines for the Commodore PET computer. In its 1980s heyday Compute! covered all major platforms, and several single-platform...
published TurboDisk, a fast loader that included C64 and VIC-20 versions. This program proved popular and was republished in the July 1985 issue of COMPUTE!'s Gazette
COMPUTE!'s Gazette
COMPUTE!'s Gazette was a computer magazine of the 1980s, directed at users of Commodore's 8-bit home computers. Publishing its first issue in July 1983, the Gazette was a Commodore-only daughter magazine of the computer hobbyist magazine COMPUTE!....
.
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 TurboDisks speed. A Commodore 128
Commodore 128
The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...
version was also included for those C128 users who still had 1541 disk drives.
COMPUTE!'s Gazette also published several other utilities that speeded up C64-to-1541 communications, including Turbo Copy (a 4-minute full-disk copier), TurboSave (a utility that accelerated the speed of disk saves) and Quick! (another fast loader).
RUN Magazine published Sizzle! in December 1987, an integrated package that included a relocatable fast loader with autoboot generation capability.