Subject: Re: random hardware questions
To: Blaz Antonic <>
From: Brian Chase <>
List: port-vax
Date: 05/04/2003 13:14:01
On Sun, 4 May 2003, Blaz Antonic wrote:

> It doesn't have a hole for CD-ROM drive in front plastic panel and i'm
> apparently too dumb to figure out how on earth a CD-ROM could fit
> there - unllike PC enclosure it doesn't seem to have that plastic
> thingy that can be removed or replaced at will. So .. do i need
> special plastic thingy to replace this one if i want to add a CD-ROM ?

The VS3100s came with varying front plates.  Some of them had cut-outs
for internal 3.5" floppies and internal 5.25" CD-ROMs or tape drives.
If you don't care so much about aesthetics, and you have the internal
drives, you can always run the system without its cover.  Other options
would be to get a cutting tool, like a Dremel, to chop out appropriately
sized and positioned holes from the plastic front panel.  Also of
general usefulness for connecting external SCSI devices is DEC's BC09J
cable; it takes the proprietary (pinout-wise) 68-pin female external
SCSI port to standard 50-pin male centronics SCSI connector.

> WHile i'm at it, how do i detach the existing plastic thingy ? I'm
> afraid to use force as i don't want to damage the enclosure :)

I've never tried removing one.  It's probably possible to replace it,
but I don't have of these systems handy to investigate.

> The only PCB that i can access inside the box is obviously SCSI
> controlelr (it has NCR chip). It also has two geatures i'm not sure
> what function they serve: first is a square chip, about the size of a
> CPU with number starting with 21... on it; i believe DEC labells their
> (CPU) chips this way; so what is this chip ?

Probably a dedicated I/O daughter card controller processor.

> Second thing is a two-row, 108 or so pin male connector (pins are
> close together like those of 68-pin SCSI connector); what is this
> connector used for ?

If it's what I think it is, there's a ribbon cable connected to it that
goes down and under the steel plate; it connects to the system board.
I'm not sure what the official DEC name for this is, but it's for the
proprietary I/O bus between the system board and the I/O daughterboard.

> Below that PCB and HD is a steel plate which i'm apparently unable to
> remove - i unscrewed the all three screws on the right side (opposite
> of the PSU) and both screw-like thingies in the front so they popped
> out from bottom plate. I don't see any other screws there yet i cannot
> (re)move the upper steel plate. Are there any screws on the back
> (perhaps near that propertiary 68-pin connector) still holding it ?

Try harder.  The steel plate does indeed come out of the case.
Underneath it is the system board, memory boards, and possibly color
graphics option board.  Maybe your plate is wedged in there a bit funny
given that you've the guts of a VAXstation 3100/m38 in the enclosure for
an m76?  ISTR that they refined the m76's enclosure very slightly,
making it a little friendlier than those of the m30s and m38s.
Generally, you only have to loosen a couple of thumb screws (slotted
for use with a flathead screwdriver).  With the I/O board mounted on
the steel plate, you'll have to disconnect it from the I/O bus and
you'll want to make sure that the external SCSI port terminator (or the
BC09J cable) is disconnected.

> My HD is RZ26L-W, made by Quantum. I can't find any info about this
> drive via Google (tried "rz26l w quantum"), just a bunch of resellers.
> Does anybody have any docs for this drive ? I'm curious as to what 'SP
> sync' jumper is used for (it's open now); write protection i figured
> out and 'spn dly' must be spin delay or something (the only one
> closed). Does that 'SP sync' jumper affect the speed of the drive ?

Look for details on older Quantum Fireball series drives, say like the
1050 or 1080.  I believe the RZ26 is similar enough to those that you
can probably use info about their jumpering with your RZ26.  I make no
promises on that advice; you'll have to use your own judgement when
looking at your drive.

> IIRC NetBSD says something about 8-bit transfers during bootup;
> according to what little info i could find this drive is not SCSI-1
> but SCSI (-2 ?) Wide drive so i don't understand why it is so slow and
> what that 8-bit blurb is all about ?

The VAXstation 3100s have SCSI-1 interfaces.  The controllers and drives
negotiate the best speed at they can both operate.  The 3100's
controller is somewhat older than your SCSI-2 drive, so the drive
t-a-l-k-s sl-ooooow to it so the controller will understand it.

> Is there some way to speed up that drive (apart from throwing it out
> the window) ?
> says it's a 5400 RPM drive with 0.5 MB of cache (!) and transfer rate
> of 32.8 MB/s (!!)

Even with the best SCSI controller in the universe, on the fastest
Pentium-VII++ 20GHz system money can imagine, I'd say 32.8 MB/s
throughput is bit optimistic for that drive.

> but it feels slower than my old 130 MB 3600 or so rpm IDE in 386SX/25
> i used to have.

Do remember that, in terms of CPU integer performance, the VAXstation
3100/m38 probably ranks somewhere in the same area as a 386SX/16 to 25.
The CVAX+ it uses is clocked at 16.67MHz (60ns cycle time).

> WHile on topic of drive speed, is there some method for drive
> benchmarking under NetBSD that would give results that can be compared
> with other machines ?

There are quite a few benchmarks available in the benchmark section of
pkgsrc.  You can also use `dd' to test sequential access performance
against the raw disk devices.  Here are some numbers from my MicroVAX
3100/20e, using various block sizes for sequential reads:

  % dd if=/dev/rsd2c of=/dev/null bs=4k count=4k
  4096+0 records in
  4096+0 records out
  16777216 bytes transferred in 36.040 secs (465516 bytes/sec)

  % dd if=/dev/rsd2c of=/dev/null bs=8k count=4k
  4096+0 records in
  4096+0 records out
  33554432 bytes transferred in 52.510 secs (639010 bytes/sec)

  % dd if=/dev/rsd2c of=/dev/null bs=16k count=4k
  4096+0 records in
  4096+0 records out
  67108864 bytes transferred in 85.811 secs (782054 bytes/sec)


  % dd if=/dev/rsd2c of=/dev/null bs=1024k count=64
  64+0 records in
  64+0 records out
  67108864 bytes transferred in 68.620 secs (977978 bytes/sec)

The numbers for my setup peaked for reads at the (somewhat impractical)
1MB block size.  Similar `dd' tests can be done for write speeds, as
long as you don't mind trashing the contents of the partition you're
testing against. The tech-perform mailing list will be able to offer you
the best help in tuning your filesystems and NetBSD to get the most out
of your drives.

> Is there any way to add a floppy drive to this box of mine ? It has 2
> SCSI controllers (that means no MFM controller i guess .. but that
> would in term mean no MFM floppy -> RX23).

DEC sold a SCSI version of the RX23 that'll work in a VAXstation 3100.
I've only ever seen one; it's in one of my m38s that I have in storage.
There do exist other SCSI floppy drives which should work.  During the
mid-1990s, SGI's used SCSI floptical drives that support standard 1.44MB
3.5" floppies as well as 20MB 3.5" floptical disks.  I'd imagine these
would work with the VAXstation 3100.  SCSI Iomega Zip and Jaz drives
also work well.

> Last question: what's your experience with use of CD-ROM drives in
> VS3100 ? Mine is KA42B, m38. Will its firmware be able to deal with
> not-so-obsolete drive like Pioneer DR-U12X for example ? The drive
> supports 512 byte blocks. If firmware won't be able to cope with it
> will NetBSD be able to use it regardless ?

I've had good luck with old Apple Mac CD-ROM drives and Plextor drives.
I think nearly at SCSI CD-ROM that supports 512 byte sectors should
work fine for you.