Re: MicroVAX I console port question. - TUHS

4 Feb 1999

...
  From owner-pups(a)minnie.cs.adfa.edu.au Wed Feb  3 11:35
PST 1999
 Date: Wed, 3 Feb 1999 11:11:56 -0800 (PDT)
 From: Brian D Chase &lt;bdc(a)world.std.com&gt;
 To: PUPS Mailing List &lt;pups(a)minnie.cs.adfa.oz.au&gt;
 Subject: MicroVAX I console port question.
 Mime-Version: 1.0

 Off-topic, but maybe somewhat related to MicroPDP-11's... I've got a
 MicroVAX I in a BA23 enclosure.  I'm presently a bit thrown by the serial
 console port.  I'm used to the 9pin MicroVAX II ports.  From what I've
 been told, the DB25-M connector for the console requires a special serial
 cable for connecting the MicroVAX I up to a terminal.  A null modem cable
 is not adequate.  
My MicroVax (I and only) handbook vintage 1984 says the cable is a "BC22D-10".

VAX Systems and Options Catalog Oct 1984 describes the BC22D-10 as
"A fully shielded null modem cable".  Two DB25F connectors, 6 wires.

The pins in use are 1,2,3,6,7,20.  I would expect that "null modem"
means (from one end to the other) connect 2-3, 3-2, 7-7, 6-20, 20-6.

The implication is that the computer might need to see DTR asserted
before it talks to the terminal.

    carl

        carl lowenstein         marine physical lab     u.c. san diego
        {decvax|ucbvax} !ucsd!mpl!cdl                 cdl(a)mpl.ucsd.edu
                                                  clowenstein(a)ucsd.edu

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 From Brian D Chase &lt;bdc(a)world.std.com&gt; Thu Feb  4
07:24:36 1999 
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From: Brian D Chase &lt;bdc(a)world.std.com&gt;
To: Carl Lowenstein &lt;cdl(a)mpl.ucsd.edu&gt;
Cc: pups(a)minnie.cs.adfa.oz.au
Subject: Re: MicroVAX I console port question.
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On Wed, 3 Feb 1999, Carl Lowenstein wrote:

...
  My MicroVax (I and only) handbook vintage 1984 says
the cable is a "BC22D-10".

 VAX Systems and Options Catalog Oct 1984 describes the BC22D-10 as
 "A fully shielded null modem cable".  Two DB25F connectors, 6 wires.

 The pins in use are 1,2,3,6,7,20.  I would expect that "null modem"
 means (from one end to the other) connect 2-3, 3-2, 7-7, 6-20, 20-6.

 The implication is that the computer might need to see DTR asserted
 before it talks to the terminal. 
Or given that everything seems to be fine on my end null modem cable-wise,
it's possible that something more serious is wrong with my MicroVAX I.
Does your handbook list what a flashing "1" LED error code means?  
I'll double-check my cabling as well.

-brian.
---
Brian "JARAI" Chase | http://world.std.com/~bdc/ | VAXZilla LIVES!!!

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 From Johnny Billquist &lt;bqt(a)Update.UU.SE&gt; Fri Feb 
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From: Johnny Billquist &lt;bqt(a)Update.UU.SE&gt;
To: "Erin W. Corliss" &lt;erin(a)coffee.corliss.net&gt;
cc: pups(a)minnie.cs.adfa.oz.au
Subject: Re: Memory Management
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On Thu, 21 Jan 1999, Erin W. Corliss wrote:

...
  The documentation that Warren gave me describes the
memory management
 scheme.  It says that when the machine is first started, the memory
 management unit is disabled -- anyone know how to enable it, and where the
 segmentation registers are (I'm assuming they are in the 0160000-0177777
 range somewhere)? 
I haven't seen anyone answering this, so here I go...

Reg.	Addr.

MMR0	777572
MMR1	777574
MMR2	777576
MMR3	772516
UIPAR	777640-777656
UDPAR	777660-777676
UIPDR	777600-777616
UDPDR	777620-777636
SIPAR	772240-772256
SDPAR	772260-772276
SIPDR	772200-772216
SDPDR	772220-772236
KIPAR	772340-772356
KDPAR	772360-772376
KIPDR	772300-772316
KDPDR	772320-772336

xy in xyP?R is:

x:	U - User
	S - Supervisor
	K - Kernel
y:	I - Instruction
	D - Data

PAR is Page Address Register
PDR is Page Description Register

Okay, so for the layout of the registers...

MMR0:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 ! ! ! !     ! ! ! \-/ ! \---/ +-- Enable relocation
 ! ! ! !     ! ! !  !  !   +------ Page number
 ! ! ! !     ! ! !  !  +---------- Page address space I/D
 ! ! ! !     ! ! !  +------------- Page mode
 ! ! ! !     ! ! +---------------- Instruction completed
 ! ! ! !     ! +------------------ Maintenance mode
 ! ! ! !     +-------------------- Enable memory management trap
 ! ! ! +-------------------------- Trap-Memory management
 ! ! +---------------------------- Abort-Read only access violation
 ! +------------------------------ Abort-Page length error
 +-------------------------------- Abort-Non resident

The page info is for when a trap/fault occurs, and tells in which page it
occured.The rest should be pretty obvious.

MMR1:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 \-------/ \---/ \-------/ \---/
     !       !       !       +---- Register number
     !       !       +------------ Amount changed (2 compl.)
     !       +-------------------- Register numbe
     +---------------------------- Amount changed (2 compl.)

Low byte is written first, and this register tells how much registers have
changed part way through an instruction, which needs to be undone to start
the intruction again.

MMR2:

Virtual address of instruction where fault occured.

MMR3:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     ! !   ! ! +--- Enable user D space
                     ! !   ! +----- Enable supervisor D space
                     ! !   +------- Enable kernel D space
                     ! +----------- Enable 22-bit mapping
                     +------------- Enable unibus map

If 22-bit mapping isn't enabled, the machine will be in 18-bit addressign
when MMU is enabled. Unibus-mapping is something I'll skip for now. You
need it for DMA on a 22-bit unibus machine only.

Note that at the end of a MMU trap/abort, MMR0 bit 15-12 must be cleared
for MMR1 and MMR2 to become active again.

...
 From a virtual address (VA), you get to the physical
address (PA) like this:

APF=VA[15:13]
DF=VA[12:0]

PA=PAR(APF)*64+DF

The PDR looks loke this:

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   \-----------/ ! !     ! \---/
         !       ! !     !   +----- ACF
         !       ! !     +--------- ED
         !       ! +--------------- W
         !       +----------------- A
         +------------------------- PLF

ACF - Access Control Field
	000 - Non resident; abort on all accesses
	001 - Read only; abort on write attempt, memory mgmt trap on read
	010 - Read only; abort on write attempt
	011 - Unused; abort on all accesses - reserved for future use
	100 - Read/Write; memory mgmt trap upon completion of read or write
	101 - Read/Write; memory mgmt trap upon completion of write
	110 - Read/Write; no system trap/abort action
	111 - Unused; abort on all accesses - reserved for future use

A - Access to page has been made.
W - Page has been written to since PAR/PDR was loaded
ED - Expansion direction
PLF - Page length field

Now, have fun...
	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt(a)update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol