You may want to adjust the sector interleave on your copy drive. Press I and then enter the sector interleave you require. The drive in question will retain that interleave setting until you change the setting to some other value or reset the drive. You won't be allowed to set the interleave to a greater value than 16, as it may make your drive malfunction with potential loss of data as a result. In addition, the interleave should not be set to zero unless your drive is equipped with JiffyDos. The interleave set feature will only be available if THE SERVANT identifies your drive as 1541 or 1571 (in all modes).
What is sector interleave anyway? When data is saved to disk it is organized in tracks and sectors. The tracks are like concentric rings on the disk, and each track is further divided into subsections much like a pie. These subsections are called sectors. To read a sector the disk drive must make sure the read/write head is on the right track, and then wait for the sector to come around to the head's position where it can be read.
This is where interleave comes in. If more than one sector on a track is to be read, which is most often the case, it is not desirable to have the sectors placed in succession. The drive needs a split second to process the data just read and send it to the computer through the serial bus. Then the next sector will have passed the read/write head and the drive will have to wait for nearly a whole revolution. When reading a large amount of data, a program for example, this waiting becomes quite noticeable. It is better to leave some space between each sector in a sequence so that the next sector is just ahead of the read/write head just when the drive needs it. Since the data has to be read in the same order it was written, the interleave between the sectors will have to be established as the data is written to the disk.
The 1541 normally uses a interleave spacing of 10 (reading every tenth sector) while the 1571 uses a interleave of 6. If your drive(s) are equipped with JiffyDos, it uses a custom interleave scheme when the interleave is set to zero. Please refer to your JiffyDos manual for details. The 1581 don't need sector interleave since it got enough internal memory to hold a whole track of data at the same time.
But why tinker with the sector interleave? The faster the drive, the less sectors has to be skipped to maintain maximum reload speed. So if the data is to be read using another drive than the one used for saving, or if it is to be reloaded using some kind of fast load, adjusting the interleave will often improve loading speed. Furthermore, if the files you are going to save or copy are not programs but data for some program, the program's access speed will often be affected by the interleave setting. Experimentation is the only way to get ultimate performance but here are some settings which can act as a rule of thumb:
Reload drive Stock Using fastloader
1541 10 6
1571 6 4-6
This table goes for program (PRG) files. For other file types the ideal interleave can only be found by experimentation. The above values may serve as a starting point, and you can try to increase or decrease these values.
