RD54 and RT-11 5.4D

From: Jerome Fine <jhfine_at_idirect.com>
Date: Sun Oct 28 07:47:16 2001

>Eric Dittman wrote:

> > Do you use RT-11 very much? Which monitor and what programs
> > do you run? Also, how did you boot RT-11?
> I haven't used RT-11 for several years. I booted from an RX50
> (and now I've tried an RX33) drive.

Jerome Fine replies:

Interesting!!!!!!!!!! Now how did you acquire a bootable RX33 floppy?
I presume from the same source as the RX50. Do you have the complete
V5.04D distribution? And now that I am thinking of it, do you have both
the RX50 and RX33 drives connected at the same time?

By the way, RT-11 is able to do an actual FORMAT (real Low Level Format)
on the RX33 drive with the RQDX3 controller. I think this was the first
(and probably last) time that DEC supported an LLF for a floppy. Of
course, it was not really of much help since the LLF for the RX33 media
results in the same LLF as is used for the HD 5 1/4" PC floppy and
of course the same capacity in terms of blocks. So at that point, with
pre-formatted 5 1/4" media available for the PC world, DEC could not
even pretend that media there were already sold with the LLF done
were unique. And since the drive was one of the standard PC options
which already have the ability to do a LLF on the PC, there was no
excuse for not being able to do an LLF under RT-11 as well.

> > Is it possible that the WRITE PROTECT button on the front panel
> > is pressed? You can determine that by sending the command:
> > If the DUMP works, then you are at least able to read the drive.
> The WRITE PROTECT is off, and I can read the drive with DUMP. I
> can even see the ODS-2 boot blocks.

Very confusing!!!!!!!!!!! While you did not show the output from the
command, I will assume that it was reasonable and that you stopped
it with a double CTRL/C command. I also showed the optional
switch (/START:789. is allowed as well with a decimal point) which
will DUMP only a single block.

If you can READ the logical partition DU0:, then I am at a complete
loss as to why you can't WRITE it. Does anyone know if the RD54
has a WRITE PROTECT jumper that can be placed on the drive?
Of course, it might also be the cables or the drive that have a
hardware problem, but that seems so unlikely. On the other hand
maybe the WRITE PROTECT button on the front panel for the
BA23 box is not lit and still pressed IN. I can't ever remember
seeing that happen. And if I am ever able to READ a drive on
RT-11, then baring my doing something explicit to prevent my
attempting to WRITE on the drive that I know about since it
would be something very explicit that would be required, I have
never been unable to WRITE to a hard drive under RT-11 when
a DUMP was already successful.

Does anyone else here have a suggestion?

Also, try just the command:
Maybe there is something funny with V5.04D of RT-11?????

> > In addition, also try the command:
> > which will also show the map between the logical MSCP units and the
> > physical hardware. Perhaps the ODS-2 mapping was different.
> Here's the output:
> .show dev:du
> Device Status CSR Vector(s)
> ------ ------ --- ---------
> DU Resident 172150 154
> DU0: is set UNIT=0, PART=0, PORT= 0
> DU1: is set UNIT=1, PART=0, PORT= 0
> DU2: is set UNIT=2, PART=0, PORT= 0
> DU3: is set UNIT=3, PART=0, PORT= 0
> DU4: is set UNIT=4, PART=0, PORT= 0
> DU5: is set UNIT=5, PART=0, PORT= 0
> DU6: is set UNIT=6, PART=0, PORT= 0
> DU7: is set UNIT=7, PART=0, PORT= 0

This looks completely correct and expected. It also says that
you booted from the RX50 which I presume is DU1: At this point,
don't try anything fancy until you can get DU0: to work. Then
you can try some tricks on RT-11.

> > I presume you are using an RQDX3 (M7555) and DS3 is used on
> > the drive. Also, which monitor are you using? A DEC distributed
> > monitor will not have any strange aspects, but a SYSGEN might.
> > RT11SJ and RT11FB use DU.SYS while RT11XM uses DUX.SYS
> > as the device driver. And check the cables on the drive a second time.
> > Finally, does the RX50 work? If not, begin to suspect hardware
> > problems?
> The RX50 (and RX33, if I swap it for the RX50) works. I'm using the
> DEC distribution. There's been no SYSGEN at this point.
> Eric Dittman
> dittman_at_dittman.net
> Check out the DEC Enthusiasts Club at http://www.dittman.net/

I am at a complete loss as to why the DU0: is not able to have an INIT
performed. One other test that might shed some light is:
and answer
press <RETURN> twice to get to the data entry part of the program.
Then type in any value that is different followed by <RETURN> and
on the next line type <CTRL/Y> followed by <RETURN>
If at this point you get an error message, then the drive is not
accepting a WRITE operation. I still will not be able to explain,
but it would be consistent.

Another test will be the command (assuming the RX50 is DU1:):
If this also does not work, then again it is consistent. The result will
be an exact copy of the 800 blocks from the RX50 onto DU0: of
the RD54, but that can VERY easily be fixed up by the command:
either before or after you send the command:

If any of these commands allow you to WRITE on the RD54, you
may have found a bug in V5.04D of RT-11.

>>Allison wrote:
>> It it was working before all you need to do is INIT the disk to establish
>> an RT file system. The problem is RT11 doesnt like 160mb as it wants
>> not more than 32mb per logical or physical drive.
>Doesn't the "/segment:5" split the disk up?

NO!!!!!!!!!!!!!!!!! This post is not the place for a seminar on splitting up
the RD54 disk into five logical partitions. Actually, that is already done by
the RQDX3, you just need to set up the MAP correctly. Once you can
that will be the time. The SET commands are trivial, but you have to
decide which logical partitions are which. In V5.04D of RT-11,
DEC omitted one instruction in the code for the secondary boot
program and as a result, RT-11 can not use a non-zero physical
partition as the system device. The extra instruction was added
in a later version, but DU.MAC can easily be fixed as well.

The command:
sets up the file structure for DU0: so that there are only 5 segments
in the file directory instead of the maximum of 31. Each file
directory segment is only two blocks (in RT-11 they always start
at physical block 6) and each of the logical (or physical depending
on how you view the mapping of the RD54) holds 65536 blocks
with block 65535 (blocks are numbered from 0 to 65535 decimal)
normally being inaccessible by convention. This means that you devote
only 68 blocks at most for the initially empty file structure set-up
out of 65535 blocks when there are 31 file directory segments.

Since each file directory segment can hold a maximum if 72 file
entries even after a SQUEEZE command is performed, having
only 5 file directory segments (from block 6 to 15) would normally
limit you to a maximum of 358 files (the last segment can hold only
70 files due to a software limitation). In practice, the actual total
for a novice would be only about half that number or even less.
THEREFORE, NOT RECOMMENDED for a partition with
65536 blocks.

If you are able to get the RD54 to work, please let us know. If
not, answers to what happens when you try the commands:
would be very helpful.

If you can get the RD54 to work, then comes the lesson on setting
up the MAP tables via SET commands so that you can access the
other physical (logical?) partitions.

Good luck!

Sincerely yours,

Jerome Fine
Received on Sun Oct 28 2001 - 07:47:16 GMT

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