>
>Subject: Re: OT for a sec: US wiring sources of info
> From: Alistair MacDonald <a.macdonald+classiccmp at slitesys.demon.co.uk>
> Date: Fri, 07 Oct 2005 17:50:53 +0100
> To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
>
>Chuck Guzis wrote:
>
>> If I remember what my friend from Aylesbury told me aobut UK wiring, it
>> isn't uncommon for a 50 amp 220 volt pair to be run to all outlets;
>
>Your friend would appear to live in a different UK to me. It is however
>common practice for the outlets to be in a ring with a 30A fuse in the
>fusebox.
Well UK and USA differ on wiring and voltage. We often have large
numbers of outlets (parallel connection) per fuse/breaker. For example
this house has 9 rooms and three breakers control the bulk of the outlets
(1957 construction). And added outlets since then are on new breakers.
This is typical of homes more than 15-20 yers old and varies a lot.
the other is MY understanding is UK is 230V where we use 115/120. Further
the mains are Line/Line in UK and here they are line/neutral. The differnce
is under nominal conditions one side of the outlet is at earth potential
(or very close). We add the third prong as earth or safety ground.
>> the fuse being in the plug of the appliance. He also mentioned that,
>> although in theory, each appliance is to be fused according to its
>> current use, the common practice is to install a 13 amp fuse in
>> everything as a replacement.
>
>Most people don't understand the difference and it is more annoying to
>get the correct fuse. It isn't helped by the manufacturers supplying
>items with the wrong fuse. Those of us who perform Portable Appliance
>Tests on things get very annoyed at having to replace the fuses on the
>first test. Anyone want any 13A fuses? 8-)
While a good practice the design differnce here is internal fuse
(or on equipment) for equipment fault and circuit (breaker box) fuse
to protects building wiring from fault or overload. fire people often
report that electrical fires resulting from circuit overload (impropper
fusing or use of under weight extension cords.) more often than an
appliance causing fires. From what you say it's done the same there
only location of the equipment fuse is at the connector. Each has
it's merits.
I may add here we also have fixed appliences that use 230V line/line
for power too allow lower line currents that come with higher voltages.
Devices like that are electric ranges, Ovens, clothes dryers and generally
any non portable appliance that would draw 20A or more at 115/120V.
US household generally have power delivers from the pole as 230V Line/Line
aand 115/120V line/neutral. A code specifies that neutral will be bonded
to earth (via pipe or ground rod) at only one point. From that point
protective ground and neutral will be distributed to all loads either as
star or bus.
Allison
Hi, does anyone have the April/June and July/September issues (Vol. 24, nos.
2 and 3) of the IEEE Annals of the History of Computing? I need these for a
research project.
Thanks!
- Evan
-----------------------------------------
Evan Koblentz's personal homepage: http://www.snarc.net
Computer Collector Newsletter: http://news.computercollector.com
Mid-Atlantic Retro Computing Hobbyists & Museum:
http://groups.yahoo.com/group/midatlanticretro/
On Oct 6 2005, 22:03, Tony Duell wrote:
> > fear it's more likely a 6530, and I assume they're unobtanium. Has
> > anyone ever come up with a kludge to effectively use a 6532
> My Commodore 8250LP disk drive has an official kludgeboard in what
seems
> to be a socket designed for an 6530. It contains a 6532, a ROM, and a
> simple TTL chip ('04 or something like that).
Sounds like a start. I obviously can't get this fixed for, er, today,
but perhaps I can look at it over the weekend. If not, it will just
have to be a static display on Wednesday.
--
Pete Peter Turnbull
Network Manager
University of York
Does anyone know what the pinout for this PTR is? This is a EECO model
TRS9200BBDED. It appears to be ann 8 bit reader and has a DB-25M connector
and mounts in a 19" rack.
Joe
>
>Subject: 8" floppy system needed to recover old game data
> From: "Barry Watzman" <Watzman at neo.rr.com>
> Date: Fri, 07 Oct 2005 11:46:29 -0400
> To: <cctech at classiccmp.org>
>
>
>Let's simplify this ... A LOT.
>
>The most common disk format (BY FAR) for CP/M was 8-inch, single sided,
>single density.
Already stated but it's very important to repeat it.
>If they are in that format, then virtually any CP/M system with 8" floppy
>disk drives can read the disks (assuming that they are still readable). It
>is very unlikely to matter what disk controller was used to write the disks,
>it is very unlikely to matter what system originally created the disks. The
>8" SSSD format is "gold standard interchangeable" among virtually all CP/M
>systems with 8" floppy drives. And it was, BY FAR, the most common CP/M
>disk format.
Most 8" softsector systems that did "other formats" also maintained
the 8" SSSD standard.
>Finding a working CP/M system with 8" drives should not be difficult. I
>have 3 of them here (I'm in Ohio, USA). There are still many thousands of
>running CP/M systems around. A slightly greater problem is getting the
>files moved from the 8" CP/M floppy disks to another [more useful] form of
>media. What you really want is a system with both 8" and 5.25" floppy
>drives, and a PC with 5.25" floppy drives. Such a system would allow you to
>move the files from 8" CP/M to DOS/Windows, which is probably the objective.
The latter, moving the files is trivial. Procomm on a PC and any of the
modem programs on the CP/M system is easily done. Some systems like mine
runs 3.5" floppies as well plus a program called dos to write 720k format
DOS floppies which is very handy! Other do it by writing 8" to 360k 5.25
and relying on a pc with same disk and using one of many programs to read
the disk at the file level.
>My experience in reading 8" diskettes written in the 1970's has been
>excellent. I have hundreds, probably a couple of thousand such disks, and I
>have only had a single digit number of diskettes that I have been unable to
>read out of all of those. Others who have actually had experience with
>large numbers of 8" disks also report very high success rates with disks
>that have been stored in climate-controlled environments. Now if the disks
>were outside in a garage for 20 years, that would be another matter of
>course, but for well stored disks, readability is not usually an issue.
My experience is mixed, I generally assume readable but occasional bad media
show up. I've had more likely due to poor storage they were subjected to
beforehand. A side note is that most of the bad media was mid 80s 3M
manufacture [remember the "blackwatch" audio tape that binder crapped after
a few years] or poorly stored. My PDP-11 (RX01) disks are typically 35
years old for some masters. Yet some of the early 80s cheap (third party)
8" media has failed. Maxell Dysan and BASF were always the best and I still
have an unopened box or two.
>It is possible that the disks are not SSSD (single sided, single density),
>and if that is the case, then the problem becomes far more complex. Once
>you get away from 8" SSSD, there is no standard disk format, rather there
>are hundreds of different formats specific to each implementation of CP/M.
>This could [greatly] complicate recovery, however, under no circumstances
>would this make recovery impossible. CP/M is highly adaptable, and with
>some effort (programming) it would be possible, first, to determine the
>format, and, second, to adapt any CP/M system to be able to read any disks
>for which it had the correct type of drive.
The only other format that shows up is Intel MDS using the double density
M2FM(oddball), I must have a dozen of these that I can't read. I point
this out as some games developers used MDS as their development platform
and debug platoform using the MDS ICE. Usually thier budget was smaller
and they used generic systems.
>In general, unless the format is ***VERY*** non-standard, it doesn't matter
>what the controller was that wrote the disks. Most systems used Western
>Digital 17xx controllers, some did use NEC 765 controllers (which existed
>for a couple of years before the PC came out), and a few used discreet logic
>controllers. But for the most part (and in particular between the WD and
>NEC based controllers), disks were interchangeable with regard to being
>READ.
FYI: the NEC 765 was sampled in early 1980, production 1980 4thQ, IBM PC was
Q3 1981. It wasnt a few years. The 1771/1793 was the defacto CP/M FDC
through 1981 and dominent after that with only new designs after '81 picking
up on the 765 (compupro and some of the system on a single board vendors).
In any case for 8" SSSD it was not an issue as both NEC and WD controllers
were fully capable and compatable.
>A few people mentioned hard-sectored media. While hard sector 8" disk
>systems did exist (I have two of them here), it was very, very rare for
>hard-sectored media or systems to run CP/M. Invariably, systems using
>hard-sector 8" media ran proprietary operating systems. You can assume that
>any 8" CP/M system was soft-sectored and be correct at about the 99% level.
Hard sector 8" system were rare, unusual and many of the host systems
were difficult to program (new bios) or unsuitable for CP/M operation.
Another watch for thing. I have media (Maxel 2Dxd, two sided) that was
usually used for two sided and the sector hole is different and some older
drives do not see index as a result. This occured to me using an old
SA800 and the media was actually used and formatted as as single sided
SD on a Compupro Disk1 using QUME drives. It was a simple matter of using
an 8" drive that could sense index in either location (sa860). I mention
this as users and integrators of CP/M systems often did an occasional
strange thing and if a disk doesnt read it can be an innocent error thats
easily fixed.
As been repeated else where and by myself the 5.25" world was not as orderly.
Allison
Let's simplify this ... A LOT.
The most common disk format (BY FAR) for CP/M was 8-inch, single sided,
single density.
If they are in that format, then virtually any CP/M system with 8" floppy
disk drives can read the disks (assuming that they are still readable). It
is very unlikely to matter what disk controller was used to write the disks,
it is very unlikely to matter what system originally created the disks. The
8" SSSD format is "gold standard interchangeable" among virtually all CP/M
systems with 8" floppy drives. And it was, BY FAR, the most common CP/M
disk format.
Finding a working CP/M system with 8" drives should not be difficult. I
have 3 of them here (I'm in Ohio, USA). There are still many thousands of
running CP/M systems around. A slightly greater problem is getting the
files moved from the 8" CP/M floppy disks to another [more useful] form of
media. What you really want is a system with both 8" and 5.25" floppy
drives, and a PC with 5.25" floppy drives. Such a system would allow you to
move the files from 8" CP/M to DOS/Windows, which is probably the objective.
My experience in reading 8" diskettes written in the 1970's has been
excellent. I have hundreds, probably a couple of thousand such disks, and I
have only had a single-digit number of diskettes that I have been unable to
read out of all of those. Others who have actually had experience with
large numbers of 8" disks also report very high success rates with disks
that have been stored in climate-controlled environments. Now if the disks
were outside in a garage for 20 years, that would be another matter of
course, but for well stored disks, readability is not usually an issue.
It is possible that the disks are not SSSD (single sided, single density),
and if that is the case, then the problem becomes far more complex. Once
you get away from 8" SSSD, there is no standard disk format, rather there
are hundreds of different formats specific to each implementation of CP/M.
This could [greatly] complicate recovery, however, under no circumstances
would this make recovery impossible. CP/M is highly adaptable, and with
some effort (programming) it would be possible, first, to determine the
format, and, second, to adapt any CP/M system to be able to read any disks
for which it had the correct type of drive.
In general, unless the format is ***VERY*** non-standard, it doesn't matter
what the controller was that wrote the disks. Most systems used Western
Digital 17xx controllers, some did use NEC 765 controllers (which existed
for a couple of years before the PC came out), and a few used discreet logic
controllers. But for the most part (and in particular between the WD and
NEC based controllers), disks were interchangeable with regard to being
READ.
A few people mentioned hard-sectored media. While hard sector 8" disk
systems did exist (I have two of them here), it was very, very rare for
hard-sectored media or systems to run CP/M. Invariably, systems using
hard-sector 8" media ran proprietary operating systems. You can assume that
any 8" CP/M system was soft-sectored and be correct at about the 99% level.
3 or so meter grounding rod driven into the earth and then attached with a single run of wire to the meter box and the service panel. Current standards usually require 12 gauge copper wire with three wires in it for 110v runs. White, black, and a ground wire (usually 14 gauge). For the 110v runs, each has the ground wire and white wire connected to the panel's ground. Black goes to the breaker and becomes the hot lead to circuits. The ground wire should be connected to any metal boxes and should be attached to the ground terminals on switches and outlets.
hope that covers what you were asking.
What is the earthing arrangement?
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh
I've been looking for a list of the various hard drive units available
for the PDP-11 and their capacites, but have not been able to find one
online. Can anybody help me out here?
On Oct 6 2005, 18:25, Dwight K. Elvey wrote:
> I've seen this done for pinball machines.
[ ... ]
> http://www.6502.org/oldmicro/buildkim/buildkim.htm
Thaks -- I'd seen that link but it's good to know someone's seen
another instance in real life :-)
--
Pete Peter Turnbull
Network Manager
University of York
