On Tue, Nov 13, 2018 at 1:47 PM Ethan Dicks via cctalk < [email protected]> wrote:
> 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. > > Is Opcode #10 the "Enter MRSP Mode" or is that something else? > I'm still not sure what it does, but it was present in the early 23-089e2 firmware, and gone (acts as no-op) in the later 23-294e2 and 23-389e2 firmware versions. MRSP mode requires a command 12 (hexadecimal?) according to this page: http://www.willsworks.net/pdp-11/tu58-emu but neither the 23-089e2 nor 23-389e2 firmware seem to include that. I haven't checked 23-294e2. Maybe there are other firmware versions that include the Enter MRSP command, or maybe I'm not correctly understanding how the command packet parsing works in the firmware.
