Turbo tape
Turbo Tape is the name of the most famous cassette fast loader . Cassette fast loaders are a whole series of programs for Commodore home computers, especially for the C-64 , which accelerate the loading and saving of programs on compact cassettes . Often all of these programs were colloquially referred to as turbo tape.
technology
The recording format for the datasette implemented in the Kernal (operating system) of the Commodore home computer came from PET 2001 from 1976/77 with its much smaller memory and was optimized for high data security instead of high speed. All data blocks were simply written twice and verified when loading in order to be able to compensate for drop-outs of the tape. Furthermore, very long marking lengths were used for data recording, each bit was written with two marks (short-long or long-short), each byte was given a parity bit , and the bytes were separated from one another by another marking in order to be able to recognize them reliably when reading can. Overlong headers were also used to compensate for very long unrecordable parts of the tape at the beginning of the cassette. Due to all these properties, the effective bit rate of the user data was limited to approx. 300 bits per second. With the PET 2001, the maximum loading time of a memory-filling program (approx. 3 KiB) was less than two minutes, but with the C64, loading times of one-part, memory-filling programs (approx. 50 KiB) were over 20 minutes, multi-part programs could require even longer total loading times .
With better tape material, which became inexpensive in the course of the 1980s, it was possible to dispense with double recording, to record each bit with only one marker (short or long), instead of using a single checksum instead of the parity bits , bytes no longer to delimit, and to shorten the marking lengths and the opening credits considerably, without provoking an excessive probability of failure of the ligaments. As a result, ten times the amount of user data could be accommodated on a given tape length, the maximum loading time for one-part programs was now well below 3 minutes.
The various accelerator programs each implemented their own tape formats optimized for high data density. The compatibility of these formats with each other and with the original format was not taken into account.Instead, the appropriate quick loader program - in order to save memory and time, only the portion required for reading in the data - was installed in the original Commodore recording format directly in front of the actual program, which was then saved in the compressed format played on the tape.
Since with the Datasette, in contrast to the Commodore floppy disk drives, it is not the data transfer from the drive to the computer (see VC1541 # Langsamkeit_und_Floppy-Speeder ), but the recording format of the data that is the limiting factor, the cassette fast loaders only work when the data is loaded have also been recorded beforehand with the appropriate quick storage program. Programs that have been saved in the Commmodore standard format cannot be loaded faster with such a quick loader.
The denser recording on the tape was also combined with a packer by later fast loading programs , which resulted in a reduction in the volume of data stored and thus a further shortening of the loading time.
The "sound image" of the stored tones differs significantly from the standard storage (see audio example under Datasette ). The sound frequencies are generally higher. It was therefore no problem for experienced users to determine by listening to a data cassette in an ordinary audio cassette recorder whether they were recorded in the standard Commodore format or with a fast loader.
distribution
Almost all games sold commercially on cassettes from around 1983/84 onwards used their own fast loader, almost always in connection with a short lead in the standard Commodore format, which then automatically reloaded the rest of the program in its own format. Most commercial fast chargers did not shorten the marking lengths quite as much as the original turbo tape in order to reduce the number of warranty claims due to illegible tapes. The copy protection of these tapes was often integrated directly into the fast loader by encrypting data, changing the sequence or storing it mixed with useless filler data.
Well-known "fast charger"
- Turbo Tape 64
- Programmed in 1983 by Stephan Senz for the home computer C-64 . The program was later published for the C16 , C116 and Plus / 4 . In 1987 an extended version Turbo Plus (by Andreas Arens) followed, with additional basic commands, correction of some software errors of the operating system and a scroll function, in which one can scroll listings on the screen back and forth.
- V3 turbo tape
- V4 turbo tape
- Turbo Tape 61K
- Flashload
- SuperTape D2
- MultiTape I
- Hypratape 64
Tape fast charger in modules
Some plug-in modules (cartridges) have built-in tape quick chargers. This offers an enormous advantage: You don't have to wind to the fast charger and load it before winding to the program and loading it from tape.
Have a fast charger included (at least) the following modules:
- Final Cartridge 2
- Final Cartridge 3
- Action Cartridge 6+
- Nordic Power 2.1
- Action Replay 6
Action Replay 6 uses its own format with approx. 2200 bits per second. The other cartridges use a bit rate of approx. 3700 bps and are compatible with most TurboTape versions.