Cut and pasted from Wikipedia, not that it has any
Deep history of the subject, but to start the
conversation:
* Data scrubbing?is an error correction technique which
* uses a background task that periodically inspects memory
* for errors, and then corrects the error using?ECC memory
* or another copy of the data. It reduces the likelihood that
* single correctable errors will accumulate; thus, reducing
* the risk of uncorrectable errors.
Some on-topic hardware relation:
I first found out about data scrubbing back when it
was a way to deal with flaky DRAM (what Wikipedia calls
"Memory Scrubbing".) Mid-70's stuff. Later found out
that the Xerox Alto had done it in that era too. Not
sure where it first originated, I would be surprised
if this hadn't been done back to the first storage media.
In the context of large data/disk archives it is reassuring
to have this done not just at the media layer, but above
the transport (e.g. SATA or SCSI or USB bus) layer.
e.g. I store my files as bzip2 format, and every so
often not just make sure the drive thinks it can read
the sectors, but that also it passes a bunzip2 -v checksum
validation. This habit probably dates from flaky SCSI
bus/network protocols in the past that had this odd
way of dropping or mangling random bytes or sectors
without any error indication.
When I'm truly paranoid not only do I count on bzip2 checksums
but also resort to storing MD5's or SHA-1's of the
uncompressed contents.
Every so often I get ultra-paranoid and worry that the file
System is not mangling files but simply losing them. It's been
A long time since I've witnessed this, but storing the MD5's/SHA1's
In a text listing gives me some reassurance. Of course the
Filesystem might not just lose the file but also hide that it lost
The file by removing the file from the listing so I also print out
The listing and attach it to the drive/tape/CD etc... this is getting
To 2001/HAL eras of paranoia to talk about this using a
Computer (never mind locking ourselves into a space pod to discuss
Verbally and then finding out the computer can read lips!)
It is very reassuring to me to do these validations not
Just automatically but manually too. And I even purposefully
Mangle some backup files to make sure my tools would kick
Out a failure.
Probably just paranoia on my part. Wondering if others
might even be more extreme :-).
Tim.
Just got a bunch of IC?s from ?buy it all and I?ll throw in some connectors
and other stuff? lot :) have a lot of 82-84 date code chips, and some that
I personally think are kind of cool, like Signetics chips in Signetics
labeled anti-static sleeves :)
Although I have no idea what I?m going to do with well over a hundred
74ls164?s
Got a bunch of 74S logic and some oddball chips like Mostek DTMF encoder
chips, some DIP-14 or 16 Voltage regulators... A definite odd lot.
Some of these are being a pain to ID from part #?s, namely the TRW SIP
resistor networks, and some from a couple other manufacturers that don?t
seem to exist anymore nor have I had any luck finding datasheets for...
Multimeter time to ID which type of resistor array they are I guess....
Also some programmed (I presume) 68HC705 microcontrollers and some 40 pin
chips from Ztec I think it was, they are upstairs and I?m downstairs.
Hello all,
I'm looking for a bit of help in wiring up a cable for my DLV11-J. I
can understand the wiring for the BC21B-05 cable transmit, reciever
and ground lines, however I'm rather confused by the rest of the
wiring on the cable. If possible would someone be able to explain the
wiring for the cable?
I've attached the relevant pages from the 1983 QBUS Interfaces manual.
Thanks in advance for any help.
Cheers,
C. M. Gauger-Cosgrove
> From:?Ethan Dicks <ethan.dicks at gmail.com>
> Did you have to do any work on that -8/S? ?I have one that needs a lot
> of replacement bulbs and some sleuthing in the "lock" circuit (the
> switch is fine, but the machine behaves as if it's always in "lock"
> mode).
We (RICM) were very lucky with this donated machine, and everything
works. The main power supply lasted about one hour after reforming the
caps. We actually had a brand-new 40 year old spare power supply for a
replacement. We had to clean the switches, but they generally work OK.
All of the bulbs worked, but one is bright. I have been told that we
will break bulbs trying to replace the bright one so we will leave it
alone. The system ran for about another 5 hours before the power
supply for the PT08, PC01, PC02, and PC03 suffered the same fate and
shorted the cap in the ferroresonant circuit. New caps from eBay fixed
it.
I am interested in corresponding with PDP-8/S owners. There doesn't
seem to be very many of these slowpokes in existance.
--
Michael Thompson
Salt Water load devices were not used just for dummy loads.
in the very days of live theatere (think Vaudville) the first electric light dimmers were square wooden boxes filled a water based brine with the electrodes fitted to a wood handle.
the handle was moved up or down in the brine to dim or brighted the stage light!
i yahoo search the info once and found it interesting and dangerous.
i think the were also called "brine tank dimmers"
Bill
At 18:59 -0500 4/26/11, ard wrote:
>If you are really crazy, use containers of salt water with suitable
>electrodes in them :-). Just don't knock them over and spill the liquid
>into the machine under test.
...and do work in a ventilated area. The bubbles evolving off the
salt water will be, er, flammable, yes?
Did this with the kids, 12V supply = jump cables from my car,
foil "electrodes" in salt water, inverted test tube on a long holder,
and a candle to verify the type of gas (used the holder to move the
tube over the candle). Lucked out and collected the Hydrogen on the
first try (well, it wasn't really luck. The electrode with twice as
many bubbles had to be the H2.) They were suitably impressed. I was
impressed how fast the aluminum foil went away (into solution).
--
- Mark 210-379-4635
-------------------------------------------------------------------
Hi! I am giving away the remaining uPD7220 GDC prototype boards. If there is
anyone interested in working on a 7220 GDC project please let me know. These
boards are designed for ECB although will interface to any Z80 quite easily.
Other systems would take some work but still possible.
Also, there is a page on the N8VEM wiki for the uPD7220 V2 prototype board
with schematics, PCB layout, test software, etc. There will be a new board
coming out soon but these prototype boards work fine with some very minor
tweaks.
For more details see here
http://groups.google.com/group/n8vem/t/2b566d452dd7b460
Thanks and have a nice day!
Andrew Lynch
PS, pair this board up with an SBC-188 or your homebrew 8088 board and we
could have a completely free/open FreeDOS/OpenGEM solution!
I've uploaded photos of a Nuclear Data ND 812 system that I obtained
recently. Its a little dirty, but its a rare system. It is the
companion lab equipment that goes with the Nuclear Data ND 6600
terminal that I obtained earlier. I haven't reverse engineered all
the subsystems yet, so some of my current understanding is guesswork.
However, the system appears to consist of:
- ND 812 CPU rack chassis
- (2) peripheral control rack chassis
- 1 dual 8" floppy drive rack chassis with drives and controller
- 1 dual 8" floppy drive rack chassis containing only a power supply
- (2) ND 600 data entry terminals with 4 NIM slots each
Pictures:
<https://picasaweb.google.com/legalize.slc/NuclearDataND812#>
Bitsavers docs on the ND 812: <http://bitsavers.org/pdf/nd/>
NIM standard:
<http://en.wikipedia.org/wiki/Nuclear_Instrumentation_Module>
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://legalizeadulthood.wordpress.com/the-direct3d-graphics-pipeline/>
Legalize Adulthood! <http://legalizeadulthood.wordpress.com>
