On Sat, Nov 24, 2012 at 4:08 AM Eric Smith <[email protected]> wrote: > I spent some time reverse-engineering the firmware. There is only one > undocumented opcode, decimal 10, and I haven't yet figured out what it > does, but it definitely doesn't format a tape.
I looked at the firmware disassemblies. Opcode 10 appears to only point to code (vs NOP) on one version of the firmware https://gitlab.com/NF6X_Retrocomputing/tu58firmware/blob/master/disassembly/23-089e2.asm op_undoc_10: ld hl,l07e4 call s06a ld a,018h ld (r2003),a jp op_nop (I think the jump to op_nop is just there to handle regular opcode processing cleanup) I have TU58 drives in VAXen (11/750, 11/730, 11/725), a VT103, and one standalone unit that I pulled from an 11/725 that we bought to strip for parts to keep our 11/730 running. I really haven't explored the differences in the firmware since mostly, I've used them as intended, for loading SA Backup, Microcode patches, and, of course, as Console Media to boot the 730 and 725. -ethan
