here's the e-mail that I sent on to Mark in the hope that it would give him enough information to get his 5th Edition kernel working with a tape device. He has also now joined the list. Welcome aboard, Mark. Warren ----- Forwarded message from Warren Toomey <wkt(a)tuhs.org> ----- On Thu, Jul 10, 2014 at 05:56:04PM -0400, Mark Longridge wrote: Mark, glad to hear you were able to rebuild the kernel. I've never tried on 5th Edition. Just reading through the 6th Edition docs, it says this: ----- Next you must put in all of the special files in the directory /dev using mknod‐VIII. Print the configuration file c.c created above. This is the major device switch of each device class (block and character). There is one line for each device configured in your system and a null line for place holding for those devices not configured. The block special devices are put in first by executing the fol‐ lowing generic command for each disk or tape drive. (Note that some of these files already exist in the directory /dev. Examine each file with ls‐I with −l flag to see if the file should be removed.) /etc/mknod /dev/NAME b MAJOR MINOR The NAME is selected from the following list: c.c NAME device rf rf0 RS fixed head disk tc tap0 TU56 DECtape rk rk0 RK03 RK05 moving head disk tm mt0 TU10 TU16 magtape rp rp0 RP moving head disk hs hs0 RS03 RS04 fixed head disk hp hp0 RP04 moving head disk The major device number is selected by counting the line number (from zero) of the device’s entry in the block con‐ figuration table. Thus the first entry in the table bdevsw would be major device zero. The minor device is the drive number, unit number or partition as described under each device in section IV. The last digit of the name (all given as 0 in the table above) should reflect the minor device number. For tapes where the unit is dial selectable, a special file may be made for each possible selection. The same goes for the character devices. Here the names are arbitrary except that devices meant to be used for teletype access should be named /dev/ttyX, where X is any character. The files tty8 (console), mem, kmem, null are already correctly configured. The disk and magtape drivers provide a ‘raw’ interface to the device which provides direct transmission between the user’s core and the device and allows reading or writing large records. The raw device counts as a character device, and should have the name of the corresponding standard block special file with ‘r’ prepended. Thus the raw magtape files would be called /dev/rmtX. When all the special files have been created, care should be taken to change the access modes (chmod‐I) on these files to appropriate values. ----- Looking at the c.c generated, it has: int (*bdevsw[])() { &nulldev, &nulldev, &rkstrategy, &rktab, &tmopen, &tmclose, &tmstrategy, &tmtab, /* 1 */ &nulldev, &tcclose, &tcstrategy, &tctab, 0 }; int (*cdevsw[])() { &klopen, &klclose, &klread, &klwrite, &klsgtty, &nulldev, &nulldev, &mmread, &mmwrite, &nodev, &nulldev, &nulldev, &rkread, &rkwrite, &nodev, &tmopen, &tmclose, &tmread, &tmwrite, &nodev, /* 3 */ &dcopen, &dcclose, &dcread, &dcwrite, &dcsgtty, &lpopen, &lpclose, &nodev, &lpwrite, &nodev, 0 }; Following on from the docs, you should be able to make the /dev/mt0 device file by doing: /etc/mknod /dev/tm0 b 1 0 And possibly also: /etc/mknod /dev/rmt0 c 3 0 Cheers, Warren