Hello again,

okay, as i thought, the DECsystem 5500 _IS_ a quite perverted system. I'll
summarize all the mails now, maybe someone also gets this machine, has the =
same
problems, and also uses google. This time maybe resulting in this very
interesting thread.

To start: i have a DECsystem 5500 here, KN220 CPU, 160 MB RAM, no disks, br=
oken
operator panel, found at ebay.de for a price i don't want to mention here
because i don't want to get hated :)

After fixing the operator panel (someone seemed to be confused about the
meading of "console" and "power", there were 5 lines in some middle layers =
of
the PCM burned down, and 3 protection diodes for the serial port shorted,
thanks god the machine didn't get any problems with this, and thanks to my =
VAX
4000/200, where i hade a reference panel to check the problems), the machin=
e
falls down to some vaxoid looking prompt after showing some failures:

lots of register dumps -> you may want to terminate the SCSI bus
79? and a register dump -> NVRAM problem, i think, this is an empty battery=
=2E

If you do a "test 9e", you see all tests, the number matches the number
reported right before the CPU register dump, so you can hunt for potential
problems here.

According the the information of Magnus B=E4ckstr=F6m, this machine does no=
t just
have the MIPS CPU inside, but also a VAX CPU as some kind of console proces=
sor.
If a selftest error occurs, you fall into this "VAX mode". And really, you
can't boot pmax-compatible CDs, you can boot VAX-compatible CDs. You can bo=
ot
NetBSD/vax, VMS, Ultrix/VAX. No problem. Okay, the OS fails because of not
detecting some kind of known hardware, but it starts booting. BTW... extrem=
ely
slow :)

You can leave this VAX thingie by simply typing "exit". Here you see someth=
ing
like the familiar pmax monitor. The optical difference: VAX shows a
">>>"-prompt, pmax shows a ">>"-prompt.

If you got this far, you are done and can boot anything you want to boot.
Currently, this might be just Ultrix/RISC, which is currently installing on=
 my
new hardware. NetBSD goes home because it doesn't know about this machine.
Maybe inside, there are more things to fix to get it running. As soon as i =
find
the time, i will have a closer look inside this, maybe we get it running
somewhen.

If you get such a machine, you want to have it. The style factor of this sy=
stem
in the pmax era if about that large as the VAX 8000 series or the old 11/78=
0 in
the vax era. This pmax is in many points more a VAX like a pmax, but with t=
he
fine RISC cpu. Maybe i find some really dirty things to abuse the VAX insid=
e
it, while the MIPS executes NetBSD.

Thanks to anyone who contributed some words to the thread, i finally got th=
is
beast installing Ultrix on a RF72, and i know to have another very nice mac=
hine
in my quite nice collection.

So long... Michael

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