IIRC, the TK50 and TK70 use *exactly* the same media, with a different format. You can bulk-erase them and reformat them for either. Eric

Jerome Fine replies: As has already been stated, it is possible to BULK ERASE a used TK50 media and then use it as a TK70. Since I have done that many times, I know it is possible. It is also possible to used a completely NEW TK50 media as a TK70. If the TK50 is totally blank, then the TK70 will also be happy. I have done that as well, although ONLY once or twice since it was rare to find an unused TK50 media. At one point, there was a web page providing the characteristics of all DLT media which included TK50 and TK70. The magnetic and physical properties are IDENTICAL. The only 2 differences are: (a) CompacTape usually have a brown ID and CompacTape II usually have a blue ID (b) DEC always charged substantially more for the media with a blue label Finding a bulk eraser may not be easy. I also tried it with a large magnetic from an old speaker - about 10 lb. It seems to work, but takes about 5 times as long. On the other hand, the bulk eraser I user had a cycle life of only ONE tape at a time after which it took about 10 minutes to cool down. I was also told that if I had attempted to bulk erase until it actually did overheat (the bulk eraser, not the tape), then the life span of the bulk eraser was greatly reduced. As for the TK70 tape drive, when used with the TKQ70 controller and a reasonable blocking factor (I believe that BUP in RT-11 used 8192 bytes per record), I was able to archive about 280 MBytes per media. What was even more important was that the WRITE speed was twice (in FULL streaming mode) that for a TK50 drive. EVEN MORE IMPORTANT was that when I did a VERIFY (I do a VERIFY 99% of the time what I do an archive) the time was usually equal the the WRITE time - I assume that the TKQ70 controller has a buffer and firmware which is able to continue streaming with the next record on the TK70 while the comparison was performed with the current record. As long as the next READ took place within a reasonable time limit (maybe before the end of the record was reached), the TK70 tape drive was able to continue in streaming mode. Sincerely yours, Jerome Fine -- If you attempted to send a reply and the original e-mail address has been discontinued due a high volume of junk e-mail, then the semi-permanent e-mail address can be obtained by replacing the four characters preceding the 'at' with the four digits of the current year.

As others have mentioned, all you need to do is bulk erase them and they'll work perfectly well. If they are official release tapes, you might consider imaging their contents before bulk-erasing ... you never know, you might have some interesting software! Antonio -- --------------- Antonio Carlini arcarlini at iee.org