RL02 Disk Cartridge Problems - why that particular pack is junk

The RL01/RL02 manual that I won on E-Bay last week arrived in the mail today. It has quite a good write up on the drive formatting, including the structure of each sector. The sector format is as follows: Sector Pulse: 62.5 microseconds, generated by slots on bottom of disk hub Header (Described Below) Data 128 16 bit words, or 256 8 bit bytes, or 170 12 bit words The sector header occurs after the the sector pulse and contains the sector number, track number, and head number of the sector in the following format: Preamble: 47 Zero Bits followed by a 1 bit Address: 16 bits - Sector: 6 bits Head: 1 bit cylinder:9 bits Zeroes: 16 bits of zeros CRC: 16 bits generated by CRC logic when data is written to the sector Postamble: 16 zero bits There is also a "guard track" on each side of the data track,whose purpose is to cause the head to go back to the center of the data track should it drift. When a drive is told to seek to a particular sector, it reads the factory written sector header to determine if it is the correct sector. If the drive can not find this info quickly enough, it will fault. Internal drive circuitry prevents the drive from writing to any part of the header (except the CRC word). It seems to me that to correctly format one of these disks after a bulk erasure, you would have to be able to do the following: 1. Correctly position the head - probably the easiest part 2. Write the correct sector header, including addressing 3. Write the guard tracks ( I bet this is the most difficult) 4. Make sure all the header data gets written to the disk in the required 62.5 milliseconds (one sector requires 625 milliseconds to pass under the head, the data part of the sector takes 500 milliseconds, the servo pulse takes 62.5 milliseconds. 5. Create the "Bad Block" file at the end of the disk. So, looking at the above, I can see where it would very difficult to format one of these guys using a stock RL01/RL02 drive, even modified. It may be possible, however, to do it with another manufacturer's 5440 type disk drive, but I'm just guessing. -- Christopher L McNabb Operating Systems Analyst Email: cmcnabb(a)4mcnabb.net Virginia Tech ICBM: 37.1356N 80.4272N GMRS: WPSR255 ARS: N2UX Grid Sq: EM97SD