Ethan Dicks <erd_6502(a)yahoo.com> wrote: There are 5 different toggle-in bootstraps. TS-11 is one of them. As I understand it, TU80 looks like a TS-11 to software, so the original enquirer who was asking about TU80 should be all set. That is how it works with DEC OSes. It is also one option with BSD. BSD, however, offers another option, using only the magtape. Of course on the original big VAXen the magtapes were not "bootable", but Appendix B of Installing and Operating 4.3BSD UNIX on the VAX (SMM:1) contains little programs in hex that you can type into memory from the console (called toggle- in programs in reference to toggle switches that predated the console). There is a different version for each kind of tape controller. Each program is to be entered at 200 and run with certain registers manually set to the controller CSR address, etc. Each time you run one of these programs, it reads one 512- byte record from the magtape at 0 and halts. The first file on the 4.3BSD distribution tape had 512-byte records and the first 5 of them were secondary tape bootstraps for different tape controllers. You would run your toggle-in program with S 200 the right number of times to load the right secondary bootstrap and then run the latter with S 0. It would give you a = prompt at which you type the name of the standalone program you want to run. These standalone programs are stored in the first file on the tape after the secondary bootstraps, and the secondary bootstrap programs load them. Between the 5 secondary bootstraps (5 512-byte records) and the tp archive with standalone programs (in the same tape file also with 512-byte records) there were two unused records. I took advantage of this in 4.3BSD-Quasijarus0a to add MicroVAX booting ability to the same tape without breaking the big VAX boot mechanism described above. The MicroVAX tape boot program is 1024 bytes long and neatly fit in the room that was left, but because MicroVAXen boot automatically using their ROMs unlike the manual process above, the MicroVAX boot program had to be first. To satisfy this requirement I simply rearranged the order: now the MicroVAX bootblock is first, followed by the 5 big VAX secondary bootstraps, followed by the tp archive with standalone programs. The big VAX booting mechanism still works with the 4.3-QJ0a tape just like with the original 4.3, the only difference is that because the secondary bootstraps are now two records further down the tape, you type S 200 two more times than the manual says. To the software there is absolutely no difference between TK50 and magtape as long as both speak TMSCP. TMSCP magtapes are bootable on MicroVAXen just like TK50s. This is the reason why I do not make separate dist tapes for big VAXen and MicroVAXen, the same tape is used for both and you write magtapes and TK50s in exactly the same way from the same files on my FTP site. I don't need to cruft anything up: for big VAXen nothing changed except the order of boot blocks, and I simply need to update the manual to increment by 2 the number of times one types S 200. I'll do that in the 4.3-QJ0b release. MS