Jerome Fine replies: I wonder if that was done to help avoid the problems with the TK50 drive? At one point, I heard that the TQK70 was developed to be used with the TK50 in order to correct some of the problems that the TK50 drive exhibits with the TQK50 controller. During my use of the TK70 drive, I sometimes placed the TK50 on the TQK70 controller and noticed a bit of an improvement with the TK50 drive. I never investigated all of the possible modes of operation, so I can't suggest any specific improvements. As for being faster, the TQK70 / TK70 almost certainly has the ability to buffer records internally and do a read of the next record. I conclude that to be true since I note the following: (a) I often make a backup image of an RT-11 partition which requires a file of 32 MBytes. This takes about 7 minutes on a TK70. (b) I then do a verify of the file against the original RT-11 partition. Using a TK50, it was almost impossible to complete due to the TK50 drive having to rewind all the time when the program (BUP.SAV under RT-11) stopped to read the disk drive and then compare the two sources of data (tape buffer with hard disk buffer). BUT with the TK70, the verify time was also 7 minutes - leading me to assume that while the BUP.SAV program was comparing the data in the two RAM buffers, the TQK70 continued to transfer the bytes from the next tape record (always 8192 bytes) into a hardware buffer within the TQK70 controller. As soon as the BUP.SAV program finished the verify of the current RAM buffers, a read request to the TQK70 that took place sufficiently soon before the end of the tape record on the TK70 media was reached was able to keep the TK70 tape drive in streaming mode and no rewinds were ever (or extremely rarely) required. I fail to understand how else the verify time was also 7 minutes. If anyone else has an alternate explanation, it would be appreciated! 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.

Jerome Fine replies: The aspect that I think is not being considered is that the comparison between the ( TQK50 / TK50 ) and the ( TQK70 / TK70 ) was run using the IDENTICAL program (BUP.SAV) running under RT-11. Since the verify program runs efficiently only with the TK70 drive, it seem to be the hardware which makes the difference - or at least the firmware on the TQK70 controller - which is outside the software for both RT-11 and the BUP.SAV application program. Again, I can only conclude that the ( TQK70 / TK70 ) keeps the streaming tape reads of the TK70 in operation by starting the next read of the next record on the tape without being asked to do so by either RT-11 or the BUP.SAV program. If I were to make a guess, it might be possible to verify this by the use of a test program. Perhaps 10 tape records could be read after which the test program would idle until the tape movement of the TK70 stooped. Then the test program would read 1 more tape record and the user could manually observe if there was any tape movement. If YES, especially if there was first a backward motion followed by a forward motion, I would conclude that the TQK70 had scrapped the extra record read - if that was ever the actual situation. BUT, if NO (no additional tape movement), then the TQK70 had obviously stored and saved within a hardware buffer on the TQK70 the eleventh (next) 8192 byte record. Further tests and timing might be able to establish just how long the test program can wait to issue the next read of the next tape record (after the current tape record has been received) before streaming motion is lost on the TK70. The basic timing information is that 32 MBytes are written in about 7 minutes using 8192 byte records - if my math is correct, about 100 records per second. So a delay of even 1 millisecond between each read of each record would quickly become too much of a delay. I am not sure where this paragraph is leading, just a few thoughts being written down at this point. 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.