From 296d06f007d20630147f02b9dd4a7b07acba7913 Mon Sep 17 00:00:00 2001 From: Ken Unix Date: Sun, 14 Jan 2024 08:07:00 -0800 Subject: [PATCH] 3B Tape Drive Info 3B Tape Drive Info --- 3b2-Tape-Drives.txt | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 3b2-Tape-Drives.txt diff --git a/3b2-Tape-Drives.txt b/3b2-Tape-Drives.txt new file mode 100644 index 0000000..8470f10 --- /dev/null +++ b/3b2-Tape-Drives.txt @@ -0,0 +1,81 @@ +Edited 1-13-2024 + +There have been two major families of cartridge tapes on the 3B2 family, +and they are not at all interchangeable. We'll describe them here in +case you're sorting through what's in front of you. + +23MB Cartridge Tape Drive Model 3b2-400 + +The first tape drive available for the 3B2 family was the 23 megabyte +Cartridge Tape Drive, and these are not compatible with any of the +later SCSI drives. It was standard equipment on the 3B2/400 and was +available in the XM expansion module for the 3B2/300, /310 and the /400. +As far as we know, the 3B2 is the only system that can read these tapes. + +These units use the CTC driver and are accessed via the device +/dev/rSA/ctape1. There is a special ctccpio command that is able to put +the device into streaming mode, but we've seen enough problems with +this command that we prefer to use the standard cpio command for this +even though it's a bit slower. A noticeable feature of the non-streaming +mode is the very annoying back-and-forth running of the tape while +reading: we've heard it described as "wheezing". + +A particular oddity of these tape drives is that because they "look" +like a (very large) floppy disk drive, the drive provides a block device +interface (/dev/SA/ctape1), in addition to the expected character +(aka "raw") device interface (/dev/rSA/ctape1. This means that it's +possible to mount a tape drive as a filesystem. It works, but it's so +slow that it's hard to convey just how painful this is. + +Our particular unit is a Cipher FloppyTape 525 (model 960273), and it is +branded with AT&T part number KS-23165. It uses a floppy disk interface +with the familiar 34 pin card-edge connector as found on older 5-1/4" +floppy drives. A distinguishing mark of this drive is the flip-up lever +that is used to engage the tape after insertion: most of the drives +shipped with the 3B2 were of this type. We understand that there is also +a similar drive made by Wangtek that looks very much like the SCSI units. + +Our understanding of these drives is that they should not use the same +DC600 cartridge tapes as do the 60 and 120 MB SCSI drives, but after +recently reviewing the 3B2 service documentation we are no longer of +this view: AT&T says that DC600 tapes can be use in all their drives. +This is good news: we've been telling people for 10 years that they have +to use special tapes. Oh well. + +It is possible to add a 23 MB tape drive to the 3B2/600 and newer units: +we simply install the CTC I/O card (CM195H) into the 3B2/600 and install +the CTC driver. We've done this on our system, though the mechanical +arrangements are "suboptimal". Because the 23MB drive doesn't really have +any provisions for external cabling. the only real way to do this is to +mount the 23MB unit inside the cabinet and put the displaced SCSI tape +drive into an external case: then use "regular" external SCSI cables to +connect them. + +This "floppy tape" interface is used in other computer systems, including +many on the PC. As such, the Linux floppy tape project might prove fruitful +for those determined to read and write many tapes on their own systems. +We are not even close to motivated enough to try this ourselves, but we'd +surely love to report on the experiences of others. + +60/120MB SCSI Tape Drives Model 3b2-700 + +The 3B2/600 and later models (including the low-profile /522) all came with +SCSI tape drives of either 60 or 120 megabyte capacity, and these are +standard units as found in many other pieces of equipment. + +We believe that AT&T only used Wangtek drives, and they are of the type +where you push the tape in, hear a click, and let go: now the drive is +engaged. To release, just push again and the tape pops out. The drives +from AT&T have a small "60" or "120" stamped on the faceplate to report +the capacity. + +These drives all use the ST01 driver, and the device name is /dev/rSA/qtape1. +Not surprisingly, there is no block device. + +A 120 MB drive can read a 60 megabyte tape but cannot write one. Neither +of these drives can read or wrote the 23 MB format. Sorry. + + + +From Steve Friedl's 3B2 Tech Tips unixwiz.net/3b2/tapedrives.html +