>From: "Tom Jennings" <tomj at wps.com>
>
>I've been working on my car project
>(http://wps.com/AMC/1970-AMC-Hornet/index.html) because car season
>is coming up soon enough, but I peeled time out for the Nova here
>and there.
>
>I originally repaired a popped +5V logic bypass cap on the
>Read/Write Board, (some monolithic ceramic job), and changed all
>the funky old caps for new ceramic disks. That worked for 20 - 40
>hours of operation without a single error. Disk had formatted with
>zero media defects. Then the disk started throwing read errors
>that moved around (bad blocks later good; more and more bad
>blocks...). Diagnostics never indicated any error other than read
>errors; seek, format, diags all run 100% perfect except read
>errors.
>
>I suspect the Read/Write Board. So I ordered modern monolithic
>replacements for the remaining old mono chips from Digikey, and
>shotgunned all the old electrolytics etc for good measure, in two
>places electrolytics replaced with tantalums (didn't have
>.82uF's).
>
>Install board with all new chips and alcohol wash, format -- hard
>100% read failure! D'OH! Long story short, I found internal +6V
>was not; turns out I installed a tant backwards. doh. New tant,
>+6V fine.
>
>Formats, reads OK, then errors again! Sheesh! System has been on
>for two hours (I'm getting paranoid, so temp stabilize the whole
>thing); halted diags, loaded disk heads, installed drive cover,
>pushed into the rack, left for an hour for the drive temp to
>stabilize (this is a religious rite, might as well kill a chicken)
>then format and test again.
>
>After warm-up, it's worse. Signals all through the path look
>OK, hot and cold. I can see no difference, but this is 10 MHz
>NRZ data, in a two-state amp with AGC. I think I'm screwed.
>
>
>The R/W board is a piece of work too. I suspect it's an early
>revision, as the board is a hack job, covered in cut traces,
>components and jumpers on the bottom, and there's a !#$%!! trimpot
>crammed in somewhere as well as kludgey RC (lopass) networks in
>some digital logic. Plus, the PC board was milled out for access
>to a middle layer. Not Good. Plus, it doesn't match the schematic
>(though it's close enough to poke around in with a scope).
>
>Photos of the nasty board here,
>
>http://wps.com/NOVA4/pitchas.html
>
>About halfway down.
>
>
>Anyone got a spare board?!
Hi Tom
Most of these old circuits used 1-shots to decode things.
Take a look at these to see if the timings seem reasonable.
Most have pulse widths around 0.7RC.
Dwight
>
>Subject: Information on IC 8287 help
> From: "Dwight K. Elvey" <dwight.elvey at amd.com>
> Date: Mon, 25 Apr 2005 09:30:35 -0700 (PDT)
> To: cctalk at classiccmp.org
>
>
>Hi
> In may searches for a DP8303, I have found nothing.
>I did find with the help of those in this group that
>the 8304 was the same except non-inverted. Looking
>for this part, I found that several places list
>a 8286 as being the same. This is also refered to
>as a uPD71086. While looking at the Jameco catalog,
>I found the next list stated as an inverting buffer
>with the number 8287. I believe this may be the same
>as the 8303 that I've been looking for.
> Can anyone tell me what the pinout is for either
>a i8287 or a uPD71087 ??
>Thanks
>Dwight
the 8286/7 is an intel part. the 8286 is non inverting and the 87 inverts
data. They are both octal bidirectional bus transceivers.
look it up here as "8286" to get a full PDF datasheet.
http://www.datasheetarchive.com/index.html
Allison
>From: "Scott Stevens" <chenmel at earthlink.net>
>
>On Sat, 23 Apr 2005 16:11:11 -0700 (PDT)
>Vintage Computer Festival <vcf at siconic.com> wrote:
>
>>
>> I'm currently using Anadisk to dump disks into image files. The
>> problem is, Anadisk, like 22disk, is retarded. If it hits an error it
>> skips the sector but does not put a blank sector in the image file.
>> You have the option of placing a sector header before each sector, but
>> for manipulating disk images, this is a piss poor way to mark missing
>> sectors. Anadisk also has the annoying habit of ignoring the start
>> and finish cylinders and merrily proceeds to read the entire disk,
>> relegating the need to ask you what cylinders you want dumped
>> superfluous.
>>
>> Is there anything in Linux that will dump a disk image and put blank
>> space where bad sectors are? It's not certain if dd does this.
>>
>> I'm sick of the crap programming of others. Must I write *EVERYTHING*
>> myself?
>>
>
>Well, the cool thing about the free Unices (and Linux) is that you can
>dig into the source code for dd and find out. And if it doesn't put
>blank space where errors occur, you can modify it to do so. Perhaps
>with a command-line switch option, if one doesn't already exist.
>
>> I'm sick of the crap programming of others. Must I write *EVERYTHING*
>> myself?
>
>Naw, just the bit that will scratch your particular itch. And if you
>make changes to dd and submit your changes back, nobody else will have
>to rewrite it either.
>
Hi
Not only should it pad the empty space but it should also
write the buffer values that may have been read if it was
just a crc error on the data portion. These are often just
missing one bit and can be recovered with a little bit of
work.
Dwight
>Subject: Re: small valves and RE: OT
> From: "Dwight K. Elvey" <dwight.elvey at amd.com>
> Date: Mon, 25 Apr 2005 09:38:10 -0700 (PDT)
> To: cctalk at classiccmp.org
>
>>From: "Allison" <ajp166 at bellatlantic.net>
>>
>>Myself as well. The design of this radio is early 50s. I have a similar
>>circuits from the 1960 RCA tube manual that require only A and B(HT) voltages.
>>However this radio had a battery based on destructive examination and markings
>>that provided 7.5V, 1.5V and 90V. So the likely case is "C" voltage or as
>---snip---
>
>Hi
> The 1.5v cell was most likely for the panel light.
>This was common on many of the battery powered sets.
>Dwight
>
Nope, No dial light. I opened the chassis up and traced the 1.5V.
It runs the audio output 3v5 other half of the filiment.
I suspect they did that to balance the filiment currents.
Odd but, thats the story.
Allison
>From: "SP" <spedraja at ono.com>
>This is the old OS named Oasis. I knew Oasis in 1986, in one version for the
>Olivetti M-20. I couldn't take the manual and disks before they go to the
>dumpster when my old employeer went down (together with one M-20, one AT&T
>3b1, some Amstrad PCW's, some Olivetti M-24 and M-28, and so on... all with
>software, licenses, and documentation).
>
Hi
If anyone has Oasis for the M-20, I'd love to get a copy. Infact
If anyone has any software for the M20 I would be interested in
seeing what you have.
Dwight
>From: "Stan Barr" <stanb at dial.pipex.com>
>
>Hi,
>
>Tony Duell said:
>
>
>>
>> I must try the circuit that was in Elektor a couple of months back to get
>> 90V from low-voltage batteries.
>
>See http://hometown.aol.co.uk/kitradioco/uk.htm for a commercial one,
>it even looks like a battery. But IIRC you're like me - you don't like
>_buying_ things you can make!
>
Hi Stan
I've done similar. I've taken one of those small 100W
inverters and rewound the transformer on it to provide
all the voltages for my older battery powered Atwater
set. It just runs from a 12 volt gel cell. I tapped
of the primary to provide the filament voltage and
used the secondary with tape to provide the rest.
As I recall, there was one -C and two +B voltages.
I used no regulation, just used the right rinding
ratios. One has to remember, these old radios
were made to run form carbon-zinc cell in most cases.
I did put a pot on my C cell. The original was -4.5v
but I found that it works better, with less distortion,
when set at about -3.5v.
Dwight
>From: "John Honniball" <coredump at gifford.co.uk>
---snip---
>
>I've just remembered that Magic Eye valves/tubes have (I think)
>an amplifying triode in the same envelope as the indicator. And I
>think they're internally linked together. Does anyone have any
>data on these gadgets that would show this sort of information?
>
Hi John
If you remember the tube number, you can find
some information at:
http://www.nostalgiaair.org/Tubes/
They alos have quite a few schematics for old
radios. One of the tuning eye tubes that I can
think of is the 6U5.
Later
Dwight
>From: "Allison" <ajp166 at bellatlantic.net>
>
>Myself as well. The design of this radio is early 50s. I have a similar
>circuits from the 1960 RCA tube manual that require only A and B(HT) voltages.
>However this radio had a battery based on destructive examination and markings
>that provided 7.5V, 1.5V and 90V. So the likely case is "C" voltage or as
---snip---
Hi
The 1.5v cell was most likely for the panel light.
This was common on many of the battery powered sets.
Dwight
Hi
In may searches for a DP8303, I have found nothing.
I did find with the help of those in this group that
the 8304 was the same except non-inverted. Looking
for this part, I found that several places list
a 8286 as being the same. This is also refered to
as a uPD71086. While looking at the Jameco catalog,
I found the next list stated as an inverting buffer
with the number 8287. I believe this may be the same
as the 8303 that I've been looking for.
Can anyone tell me what the pinout is for either
a i8287 or a uPD71087 ??
Thanks
Dwight
>
> I checked out sdd and it does not mention anything about errors.
Hmm,
[panther:~]$ sdd -help
Usage: sdd [option=value] [-flag]
Options:
if=name Read input from name instead of stdin
of=name Write output to name instead of stdout
-inull Do not read input from file (use null char's)
-onull Do not write output to any file
ibs=#,obs=#,bs=# Set input/outbut buffersize or both to #
cbs=# Set conversion buffersize to #
ivsize=#,ovsize=# Set input/output volume size to #
count=# Transfer at most # input records
iseek=#,iskip=# Seek/skip # bytes on input before starting
oseek=#,oskip=# Seek/skip # bytes on output before starting
seek=#,skip=# Seek/skip # bytes on input/output before starting
ivseek=#,ovseek=# Seek # bytes on input/output volumes before starting
-notrunc Do not trunctate existing output file
-pg Print a dot on each write to indicate progress
-noerror Do not stop on error
-noerrwrite Do not write blocks not read correctly
-noseek Don't seek
try=# Set error retrycount to # if -noerror (default 2)
-debug Print debugging messages
-fill Fill each record with zeros up to obs
-swab,-block,-unblock,-lcase,-ucase,-ascii,-ebcdic,-ibm
[panther:~]$
The -noerror and try=# parameters should take care about errors.
regards,
chris
