Another pass through the bulk-erase procedure should do it. I've had lots
of diskettes and tapes which were rejuvenated by a serious bulk-erase.
From: Charles E. Fox <foxvideo(a)wincom.net>
To: Discussion re-collecting of classic computers
Date: Sunday, May 02, 1999 5:30 AM
Subject: Re: Fun with degaussers
>At 07:18 PM 5/1/1999 -0700, you wrote:
>>At 09:50 PM 5/1/99 -0400, Tim wrote:
>>>That said, 12 (or even 6) is way too many errors for a floppy disk.
>>>Cleaning the heads, re-aligning, or buying new media (there are lots
>>>of places that still sell 8" floppies) may be the real solution.
>>The issue isn't with the disk I don't believe (I don't have an alignment
>>disk to prove it so I can't be sure). The goal of demagnetizing is to
>>recreate a uniform state of non-magnetism on the media.
> Yesterday one of our local industries was selling off some equipment to
>benefit Jr Acheivment, so I went down, found a 5 1/4" disk file with a
>bunch of disks, and was told I could have it for $ 2.00. The lady on the
>desk, however was determined no data could leave. I came home, returned
>with a bulk tape eraser and demagnitized them on the spot.
> However when I tried to format them with my trusty XT it spit them out as
>"can't read track 0" on both A and B drives. I formatted the disks
>successfully on a Compaq clone and a Commodore PC10, and now the XT will
>read them. Any ideas?
> Charlie Fox
> Charles E. Fox
> Chas E. Fox Video Productions
> 793 Argyle Rd. Windsor N8Y 3J8 Ont. Canada
> email foxvideo(a)wincom.net Homepage http://www.wincom.net/foxvideo
The state (Qld, Australia) main roads department are selling a job lot of 16
x HP1000 A-series systems.
Are these the same HP 1000's that are listed in the Comprehensive Computer
Catalog as being introduced in 1976? The pictures on the Main Roads Web page
do not look that old.
in Brisbane, Australia
- just a few km from that stash of HP1000's, but they are way out of my
<Bah, it's a VAX, it should be running VMS. I totally fail to understand
<why, especially now that licenses are free for hobbyist use, anyone would
<want to run UNIX on a VAX! A system like that should be part of a nice VM
Here, here! The OS (VMS) is a classic too!
>Ok, so on my distribution disk if I boot it up it comes up as RT-11 V20B
>SJ but if I boot DXMNTFB.SYS it comes up RT-11 V20B FB. What's the
>difference? Floating point?
SJ is the single-job monitor. One job is all you have, period.
FB is the foreground-background monitor. You have two jobs. The
foreground job is the higher-priority job. When it blocks, the
background job gets a chance to run (actually, completion routines
for the jobs are slightly higher than the jobs themselves).
So, you can run a data collection program in the foreground, and
the data reduction or storage program in the background.
If you need to direct terminal input to the foreground, you type
<Control-F> first, then type... To then have terminal input go
to the background job, type <Control-B>.
Later versions of RT-11 had foreground/background and up to 6
system jobs (with priorities in between background the foreground).
Former RT-11 Developer
| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com |
| Unix Support Engineering Group | (home): mbg!world.std.com |
| Compaq Computer Corporation | addresses need '@' in place of '!' |
| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ |
| Nashua, NH 03062 | "pdp-11 programmer - some assembler |
| (603) 884 1055 | required." - mbg |
Ok, it looks like the only way I have of getting source code from the 'net
on to the disks is to use EDIT and the "stuff text down the serial line"
hack in hyperterm. Assuming that I set hyperterm to send text slowly. What
are the minimum commands in EDIT to:
1) Open a new file.
2) Go into Insert Mode
3) Exit insert mode and save the file.
Executive Summary: Very Cool.
Ok, the adventure is nearly complete, the solutions are found, all that is
left is to collect the crystals at the back of the cave. Recapping the
RT/HT-11 saga ...
Overview, I've been recussitating an H-11 with dual H27 8" floppy drives
into working condition. This constitutes the first complete working example
of a PDP-11 in my collection. The system consists of a M7270 w/FIS,
M8044-Dx, H-11-5 serial, H-11-2 parallel, and H-11-Z floppy card. This
system was picked up at a local auction in two lots (one the H11 the other
the H27), the cable to the H27 had been cut off.
After taking apart the system, verifying the operation of the PSU, I put
together the minimum system (CPU, memory, and serial card) and powered it
up. I got the ODT prompt and that was cool. But I had no software for the
I then saw an advertisement for an H-11 with software that was near by and
asked if I could copy his disks. He said ok, and off I went box of disks in
hand. Only to find they were the wrong type. I scrounged a couple of mangy
disks and managed to get the HT-11B distribution disk and a disk called
"DCOPY" copied. The disk labelled DCOPY also included FORMAT so this was
the disk to have.
Next I got hold of the correct format disks from a fellow list member, and
formatted them on my system. After formatting I tried to Dcopy them and
sometimes it worked and sometimes it didn't. I suspected my drives.
Round 2 with the H-11 software owner and I format 10 disks at his place and
dcopy 10 volumes of software. One of which is the HT-11 distribution
(RT-11V10A). Encountering problems I tried the PIP command "/K" which
Megan's note described as a bad block scan. When I did this I found _lots_
of bad blocks on the disks. Very weird! The disk surfaces looked fine but I
doubted Control Data Corp was going to honor their 5-year warranty :-)
So I came home again late. At home I took the worst disk and used a
tape/video demagnetizer on it and then tried to reformat it. Half the bad
blocks went away! (now down to 12). A few more rounds of this and I finally
got the technique perfectly.
Take a stack of 1 or more but not more than 5 disks and
place them on a flat surface.
Run a demagnetizer horizontally and vertically over the disks
starting beyond the edge of the disk, crossing the disk, and then
passing over the opposite edge.
Hold the Demagnetizer about 1/4" above the disks and move it
around clockwise and anti-clockwise several times, then while
moving it in circles, slowly lift it up until it is about 12"
above the disks and turn it off.
The whole operation should take about 20 - 30 seconds.
Once I did this, the disks would format and scan with zero bad blocks and
zero retrys (no marginal blocks either).
To initialize a disk in RT/HT-11 (ver A or B) the following steps are used:
1) Format the disk.
2) Run PIP and type "DX1:/Z" (this will ask for confirmation)
3) From PIP type "DX1:/K" (this will scan for bad blocks)
If you get through step 3 with no bad blocks and no retries you have a
solidly formatted disk and it is ready for use.
Another mystery was some of the programs on the disk, in particular:
Because on my disk MACRO quit into ODT and ASEMBL failed to interpret the
In the DOC file for DCOPY that the author wrote, he gave the steps to
reassemble DCOPY.MAC and they were:
It turns out that EXPAND is the "macro" part of the macro assembler, and
MACRO is the RT-11 MACRO-11 assembler from V02 (it crashed on the V01 disk)
Now with good media in hand, I make one more pilgrammage and I should have
everything I need to really enjoy this system.
Thank you everyone for your help, it has been invaluable!