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Re: Address of second TMSCP controller




On 2021-01-26 7:57 a.m., Mouse wrote:
In addition to a broken TK70, which is being recognised fine by
NetBSD as mt0, I want to use a 40/80GB DLT on a Dilog SQ703 SCSI
TMSCP adapter.

      
NetBSD doesn't recognise it on booting.=C2=A0 I don't see anything
about addressing in the hardware wiki, does anybody know the address
where NetBSD looks for a second controller?
As far as I can tell, it doesn't.  The only TMSCP device I see is

mtc*		at uba? csr 0174500	# Tape MSCP ctlr

Since there's no other mtc in sight, I rather wonder why it's mtc*
rather than mtc0 - perhaps for machines with multiple buses?

I imagine you could add a second mtc line to your config at whatever
address you put your Dilog card at.  ISTR that DEC had a bunch of rules
for such addresses - the phrase "floating CSR space" comes to mind -
but I don't think anything keeps you from putting it anywhere as long
as (a) it doesn't overlap with any other device and (b) you tell the
kernel where you put it (in your second mtc line).

/~\ The ASCII				  Mouse
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Thanks, Mouse.  Yes, as an FE I used to have to figure out those floating assignment from charts - some DEC systems (RSTS, RT11) could not be told where to look - they had to be in the right place.  IIRC, there was a strict ranking, and to make it start looking for a device of the next rank, you had to skip the number of registers that each device took so it would get a bus timeout and then look for the next device in the list! Seems like it was intended to save core memory which was so expensive in those days!  I do remember that if you got it wrong, it would treat whatever it found as the device that should be there, used the wrong driver, and crashed!


Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype:  TILBURY2591 nw.johnson%ieee.org@localhost








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