Re: Diskette size (was: Repurposed Art (ahem...)

[Steve Malikoff via cctalk]

Eric said:
> I think Shugart settled on 5.25" for the size of a minifloppy at least a
> year, and more likely two years, before Steve Jobs would have visited. I
> don't have proof, but SA400 public intro was in 1976, and they probably
> took more than a year of development to get to that point.

For interest there's an SA-400 announcement article on page 86 of BYTE, 
December 1976:
https://archive.org/details/byte-magazine-1976-12

Steve.

Re: Diskette size (was: Repurposed Art (ahem...)

[Sam O'nella via cctalk]

Extremely interesting Fred. I hadn't heard of half of those experimental disk 
sizes.  Are those stories from your experience or from that article? (Yes I'll 
rtfm shortly).
The only odd one i have is a backup cartridge? that resembles around a 3.5" but 
is in fact closer to the mythical 12" floppy. Actually here's the picture i 
brought 8", 5.25" and a CED to show size comparison. 
http://www.main.org/ctacs/history/2015/20151001/20151001ctacs3744.html
null

Re: Diskette size (was: Repurposed Art (ahem...)

[Eric Smith via cctalk]

On Jul 19, 2017 10:15 AM, "Fred Cisin via cctalk" 
wrote:
> That Steve Jobs was pestering them for a cheap drive, but due to the
holes in his jeans and personal hygiene?, they never took him seriously.

I think Shugart settled on 5.25" for the size of a minifloppy at least a
year, and more likely two years, before Steve Jobs would have visited. I
don't have proof, but SA400 public intro was in 1976, and they probably
took more than a year of development to get to that point.

There's evidence in engineering notes recently published indicating that
Woz did some design work using a normal SA400 before Shugart was convinced
to sell Apple the SA390, which was the SA400 sans the standard drive
electronics PCB.

Re: PDP11 and Simh Floating point

[Eric Smith via cctalk]

On Jul 19, 2017 10:43 AM, "Douglas Taylor via cctalk" 
wrote:

The pdp11_fp.c code is quite intricate.  If simh was a simple simulation it
would take the easy route and use the intel fp co-processor as you point
out, but it doesn't.  It actually 'emulates' what the pdp11 would do in
hardware.


Do all PDP-11 FPP hardware (and/or microcode) implementations give the same
results in all cases? Does FIS?

RE: Removing Pitting and Rust From an Enclosure

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Chuck Guzis
> via cctalk
> Sent: 20 July 2017 14:43
> To: Brent Hilpert via cctalk 
> Subject: Re: Removing Pitting and Rust From an Enclosure
> 
> On 07/20/2017 12:02 AM, Brent Hilpert via cctalk wrote:
> 
> > A copper layer can perform some filling and smoothing function in a plating
> job.
> > Its perhaps more significant purpose however (as I understand it in my
> limited experience with having plating done*), is to provide an oxygen barrier
> for the steel substrate.
> 
> You can plate copper on steel to substantial thicknesses--it's often used as a
> filler material--plate more than you need, machine it to spec, then plate over
> with something durable (nickel is very common).
> 
> It's not cheap and probably not a do-it-yourself affair.   I don't know
> how OCD you want to get over this, but it'll be expensive.
> 
> You might also check out the finishing.com forum and caswellplating.com for
> alternative approaches.
> 
> --Chuck


I suppose really I want to stop any further corrosion and make it look at least 
presentable. I don't want to paint it, the finish is the usual silvery type 
finish (which I assume to be nickel) and I want to keep that. The biggest 
problem is the honeycomb grill on one side, that seems to be a bit corroded 
too, cleaning the rust off that with any kind of hand held abrasive is going to 
be pretty hard. I suspect the honeycomb may need to be sandblasted to get rid 
of the rust before electroplating. I will enquire with local companies about 
doing this work for me.

Thanks

Rob

RE: Removing Pitting and Rust From an Enclosure

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Paul
Koning
> via cctalk
> Sent: 20 July 2017 15:18
> To: Brent Hilpert ; General Discussion: On-Topic and
Off-
> Topic Posts 
> Subject: Re: Removing Pitting and Rust From an Enclosure
> 
> 
> > On Jul 20, 2017, at 3:02 AM, Brent Hilpert via cctalk

> wrote:
> >
> >> ...
> >
> > The yellowish plating is probably chromate conversion:
> > https://en.wikipedia.org/wiki/Chromate_conversion_coating
> 
> That sounds familiar from vague DEC memories.
> 
> As for those galvanized iron pieces attached to the cover, I have never
seen
> anything like that.  They are very unlikely to be original.  For one
thing, the
> mismatch in finish says so; for another, the fact they serve no clear
purpose
> and look like they were attached with no skill.
> 

I'll get rid of those horrible "feet", they actually prevent the machine
being moved around on a smooth surface, I will have to add rubber feet where
they are missing though.

Thanks

Rob

Re: iMac ethernet connection quit - help?

[Noel Chiappa via cctalk]

> From: Mark Tapley

> Next stop, I'll pull the cover off the machine and see whether I can
> spot any spilled battery electrolyte from the old battery or anything
> else suspicious looking on the logic board in that area

It probably wouldn't hurt to clean that area with a Q-tip dipped in distilled
water. (If you get noticeable grup on the Q-tip, repeat with a new Q-tip,
otherwise you'll just be spreading the ook around.)

Noel

Re: early (pre-1971) edge-triggered D flip-flop ICs

[Pete Lancashire via cctalk]

In 1978 the place I worked the cost per SSI/MSI TTL 38510 device was
between $100 and $200 each by the time they were released to production.
the key is the 38510 and the testing. In final use, the parts had power
applied for no more then an hour.

-pete

On Thu, Jul 20, 2017 at 1:35 AM, Eric Smith via cctalk <
cctalk@classiccmp.org> wrote:

> On Wed, Jul 19, 2017 at 11:29 PM, Ethan Dicks 
> wrote:
>
> > I have no datasheet, but I have examples on DEC M-series FLIP-CHIP
> > modules from my PDP-8/L, c. 1968.
> >
> > I am pretty sure I have examples with 1968 date codes and possibly
> > 1967 date codes.
> >
>
> Thanks! Also, the 1967 Allied catalog lists the SN7474 (flat pack) and
> SN7474N (plastic DIP), priced at $8.00.
>
>

Re: early (pre-1971) edge-triggered D flip-flop ICs

[Norman Jaffe via cctalk]

Or, in today's dollars - $58. Ouch. 

From: "General Discussion"  
To: "cctalk"  
Sent: Thursday, July 20, 2017 1:35:47 AM 
Subject: Re: early (pre-1971) edge-triggered D flip-flop ICs 

On Wed, Jul 19, 2017 at 11:29 PM, Ethan Dicks  wrote: 

> I have no datasheet, but I have examples on DEC M-series FLIP-CHIP 
> modules from my PDP-8/L, c. 1968. 
> 
> I am pretty sure I have examples with 1968 date codes and possibly 
> 1967 date codes. 
> 

Thanks! Also, the 1967 Allied catalog lists the SN7474 (flat pack) and 
SN7474N (plastic DIP), priced at $8.00. 

Re: Removing Pitting and Rust From an Enclosure

[Doug Ingraham via cctalk]

On Wed, Jul 19, 2017 at 1:52 PM, Rob Jarratt via cctalk <
cctalk@classiccmp.org> wrote:

> The TURBOchannel extender I got has a bit of rust and quite a lot of dark
> pitting on the steel surfaces. I am not sure what the finish is, whether it
> is anodized or galvanized. In any case, does anyone have recommendations
> for
> how to remove the unsightly pitting? Bear in mind that I am in the UK, so
> brands available in the US may not be available here and it may be more
> useful to know what the active ingredients are.
>

I have restored a couple of racks that have been shall we say mistreated.
The
approaches you can use are the same ones that automobile restoration people
use.

Remove the scale.  Steel brush works for this.
Fill the pits.  This might be something as simple as a sandable primer.
Prime.
Paint.

You want to use a primer and paint that is compatible.  If all you are
doing is gloss
black then there is nothing wrong with the Rustoleum product line.  The pro
version
seems to have a little better spray pattern.

There is a point beyond which the only solution is to replace or augment
the material.
You can cut out the sheet metal and weld in a new piece or you can
reinforce with
a fiberglass band aid in some cases.

If the surface is not normally visible you can remove the scale and then use
one of the rust converting primers.  A flat black topcoat will hide almost
anything
that is not directly visible.  Of course this does not apply if you are
trying to do a
museum quality restoration.

Look into restoration videos on youtube for detailed techniques.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Removing Pitting and Rust From an Enclosure

[Paul Koning via cctalk]

> On Jul 20, 2017, at 3:02 AM, Brent Hilpert via cctalk  
> wrote:
> 
>> ...
> 
> The yellowish plating is probably chromate conversion:
>   https://en.wikipedia.org/wiki/Chromate_conversion_coating

That sounds familiar from vague DEC memories.

As for those galvanized iron pieces attached to the cover, I have never seen 
anything like that.  They are very unlikely to be original.  For one thing, the 
mismatch in finish says so; for another, the fact they serve no clear purpose 
and look like they were attached with no skill.

paul

Re: Diehl Combitron

[Paul Koning via cctalk]

> On Jul 19, 2017, at 8:01 PM, Brent Hilpert via cctalk  
> wrote:
> ...
> Very nice, in addition I much appreciate the use of the period-appropriate 
> oscilloscope.
> 
> I've been offered a Tek 500 series recently, I'm reluctant to take it on as 
> they are in practice such boat anchors
> compared to a modern scope, but I hate to see them scrapped. They were *the* 
> scope of the '60s.

They are nice.  I used one for years, finally sold it after acquiring a 7603.  
The only trouble it ever gave me was air in the high voltage rectifiers, which 
wasn't all that hard to fix; the rectifier tubes were surprisingly easy to find.

paul

Re: Removing Pitting and Rust From an Enclosure

[Chuck Guzis via cctalk]

On 07/20/2017 12:02 AM, Brent Hilpert via cctalk wrote:

> A copper layer can perform some filling and smoothing function in a plating 
> job.
> Its perhaps more significant purpose however (as I understand it in my 
> limited experience with having plating done*), is to provide an oxygen 
> barrier for the steel substrate.

You can plate copper on steel to substantial thicknesses--it's often
used as a filler material--plate more than you need, machine it to spec,
then plate over with something durable (nickel is very common).

It's not cheap and probably not a do-it-yourself affair.   I don't know
how OCD you want to get over this, but it'll be expensive.

You might also check out the finishing.com forum and caswellplating.com
for alternative approaches.

--Chuck

Re: HP 300-series boot rom archive?

[r.stricklin via cctalk]

On Jul 19, 2017, at 10:21 PM, Josh Dersch via cctech wrote:

> On 7/18/2017 10:29 PM, r.stricklin via cctalk wrote:
> 
>> I don't have a 375, but I'll be glad to provide what I can. Having a sense 
>> of what, specifically, was being sought (and where to send it) would help me 
>> focus effort.
> 
> For my personal needs (which started this thread), I'm looking for a later 
> revision of the 350 Boot ROMs (later than A2).  For the 375 I need real 
> service docs.

Unfortunately, I don't have a 350 either. 310, 345, 360, and 380.

ok
bear.

-- 
until further notice

Re: early (pre-1971) edge-triggered D flip-flop ICs

[Eric Smith via cctalk]

On Wed, Jul 19, 2017 at 11:29 PM, Ethan Dicks  wrote:

> I have no datasheet, but I have examples on DEC M-series FLIP-CHIP
> modules from my PDP-8/L, c. 1968.
>
> I am pretty sure I have examples with 1968 date codes and possibly
> 1967 date codes.
>

Thanks! Also, the 1967 Allied catalog lists the SN7474 (flat pack) and
SN7474N (plastic DIP), priced at $8.00.

Re: Removing Pitting and Rust From an Enclosure

[TeoZ via cctalk]

It depends on what the object in question is for (decoration or durability) 
and what time period it was done.


Way back in the early 90's when I worked at a plating facility for the 
printing industry (Tide soap boxes, Marlboro cigarette boxes as an example) 
they used to copper plate  large and heavy steel (or aluminum which needed 
another step) cylinders. The copper layer was then diamond engraved with the 
design for each color  and then a heavy chrome plating was done for wear to 
keep the design from getting damaged from printing rolls of paper or what 
have you. No nickel plating at all back then. A final QC test was spinning 
the cylinder and running sandpaper over it to spot imperfections (shiny 
spots that show indentations where no design was) that would show up during 
printing , if it passed it went to the onsite printer for a proof print 
otherwise acid bath to remove the chrome then the lathe to cut off the 
designs and back to copper plating again. The chrome plating was pretty 
thick.


-Original Message- 
From: Brent Hilpert via cctalk

Sent: Thursday, July 20, 2017 3:02 AM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Removing Pitting and Rust From an Enclosure

A copper layer can perform some filling and smoothing function in a plating 
job.
Its perhaps more significant purpose however (as I understand it in my 
limited experience with having plating done*), is to provide an oxygen 
barrier for the steel substrate.


(* OT, FWIW: I once went through the trial, albeit educational, of having a 
chrome Scott radio chassis replated. Longer tale.
A proper chrome plate job is not chrome on steel, it's copper on the steel, 
then nickel, and finished with a few atoms of chrome.) 



---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Re: Repurposed Art (ahem...)

[Curious Marc via cctalk]

I like it, that's quite artfully done actually! Best paint job ever on an 024 
(am I right? 024, not 026 because it has no printer?). It would be perfect if 
you had a normal 024 or 026 to put right beside it with its drab gray wrinkle 
paint. What a pity it lost its keyboard. That ruined both the punch and the art 
in one fell swoop.

Marc

 

From: cctalk  on behalf of 
"cctalk@classiccmp.org" 
Reply-To: , "cctalk@classiccmp.org" 

Date: Tuesday, July 18, 2017 at 6:03 AM
To: "cctalk@classiccmp.org" 
Subject: Repurposed Art (ahem...)

 

 

Re-purposed art or vandalism?

 

http://www.ebay.com/itm/253015301943

 

Ed

--

Ik email, dus ik besta.

 

 

Re: Removing Pitting and Rust From an Enclosure

[Brent Hilpert via cctalk]

On 2017-Jul-19, at 11:37 PM, Rob Jarratt via cctalk wrote:
>> -Original Message-
>> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Chuck Guzis
>> via cctalk
>> Sent: 20 July 2017 03:34
>> To: Fred Cisin via cctalk 
>> Subject: Re: Removing Pitting and Rust From an Enclosure
>> 
>> On 07/19/2017 07:13 PM, Fred Cisin via cctalk wrote:
>> 
>>> In most places other than the south and Chicago, Coke and Pepsi are what
>>> is used.   I don't think that SNL (Saturday Night Live) ever did a "No
>>> Coke; RC" skit.
>> 
>> There's also some stuff called "Naval Jelly"
>> 
>> http://www.loctiteproducts.com/p/s_trmt_naval/overview/Loctite-Naval-Jelly-
>> Rust-Dissolver.htm
>> 
>> I was going to suggest leveling with Bondo, but that seemed the cheap way to
>> go.
>> 
>> I've used Bondo many times to fill missing bits of broken plastic
>> faceplates.   A little sanding and a coat of paint and it looks
>> downright presentable.
>> 
>> Machine tools (particularly Chinese ones) that use gray iron castings are 
>> often
>> smoothed with a Bondo-like putty before being painted.
>> (They're not very pretty under the putty).
>> 
>> If you were really serious about this, you could plate a generous coat
>> of copper, sand it smooth, then plate a layer of nickel.   But if you've
>> never done electroplating, it's probably not a good idea to start with 
>> something
>> valuable.
> 
> 
> Well I could always see if I can get electroplating done professionally 
> without spending a fortune, although trying myself with something unimportant 
> is also an option. But first I would need to know what the finish actually 
> is. There seem to be two common finishes to the metal used in MicroVAXen, 
> DECstations and the like, one is a sort of subtle yellow, the other is a 
> silvery finish. In this case it is a silvery finish. Can anyone tell me what 
> those two finished actually are? I am guessing it is nickel. If that is the 
> case, why the copper plating first?

The yellowish plating is probably chromate conversion:
https://en.wikipedia.org/wiki/Chromate_conversion_coating

A copper layer can perform some filling and smoothing function in a plating job.
Its perhaps more significant purpose however (as I understand it in my limited 
experience with having plating done*), is to provide an oxygen barrier for the 
steel substrate.

(* OT, FWIW: I once went through the trial, albeit educational, of having a 
chrome Scott radio chassis replated. Longer tale.
A proper chrome plate job is not chrome on steel, it's copper on the steel, 
then nickel, and finished with a few atoms of chrome.)

Re: HP 300-series boot rom archive?

[Josh Dersch via cctalk]

On 7/18/2017 10:29 PM, r.stricklin via cctalk wrote:


On Jul 18, 2017, at 8:38 AM, Al Kossow via cctech wrote:


When MAME started supporting the 68K 9000s, I made an effort to go through all 
of my machines
and dump the firmware. I didn't have a 375, which is why it isn't there. It 
would be nice if
some other collectors (Bear?) would dump any firmware out of their machines.

I don't have a 375, but I'll be glad to provide what I can. Having a sense of 
what, specifically, was being sought (and where to send it) would help me focus 
effort.


For my personal needs (which started this thread), I'm looking for a 
later revision of the 350 Boot ROMs (later than A2).  For the 375 I need 
real service docs.


- Josh




ok
bear.

RE: Removing Pitting and Rust From an Enclosure

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Chuck Guzis
> via cctalk
> Sent: 20 July 2017 03:34
> To: Fred Cisin via cctalk 
> Subject: Re: Removing Pitting and Rust From an Enclosure
> 
> On 07/19/2017 07:13 PM, Fred Cisin via cctalk wrote:
> 
> > In most places other than the south and Chicago, Coke and Pepsi are what
> > is used.   I don't think that SNL (Saturday Night Live) ever did a "No
> > Coke; RC" skit.
> 
> There's also some stuff called "Naval Jelly"
> 
> http://www.loctiteproducts.com/p/s_trmt_naval/overview/Loctite-Naval-Jelly-
> Rust-Dissolver.htm
> 
> I was going to suggest leveling with Bondo, but that seemed the cheap way to
> go.
> 
> I've used Bondo many times to fill missing bits of broken plastic
> faceplates.   A little sanding and a coat of paint and it looks
> downright presentable.
> 
> Machine tools (particularly Chinese ones) that use gray iron castings are 
> often
> smoothed with a Bondo-like putty before being painted.
> (They're not very pretty under the putty).
> 
> If you were really serious about this, you could plate a generous coat
> of copper, sand it smooth, then plate a layer of nickel.   But if you've
> never done electroplating, it's probably not a good idea to start with 
> something
> valuable.


Well I could always see if I can get electroplating done professionally without 
spending a fortune, although trying myself with something unimportant is also 
an option. But first I would need to know what the finish actually is. There 
seem to be two common finishes to the metal used in MicroVAXen, DECstations and 
the like, one is a sort of subtle yellow, the other is a silvery finish. In 
this case it is a silvery finish. Can anyone tell me what those two finished 
actually are? I am guessing it is nickel. If that is the case, why the copper 
plating first?

Regards

Rob

RE: Anyone Know Anything About This TURBOchannel Card?

[Rob Jarratt via cctalk]

> -Original Message-
> From: John Forecast [mailto:j...@forecast.name]
> Sent: 18 July 2017 16:27
> To: r...@jarratt.me.uk; Rob Jarratt ; General
> Discussion: On-Topic and Off-Topic Posts 
> Subject: Re: Anyone Know Anything About This TURBOchannel Card?
> 
> Rob,
> That’s probably a J-Video board, a prototype built by DEC SRC for the J300
> series of video and audio adapters. You can find more information in Digital
> Technical Journal, Volume 7, Number 4. Around that time, mid-1994,  I was
> working on the software for a PC ISA board which would inter-operate with J-
> Video to provide network-based desktop video conferencing (see DTJ Volume 5,
> Number 2). After 2 groups that were working on this were shutdown within a
> month of each other, I decided it was time to leave the company. I don’t know
> if any further development occurred.
> 

Thanks for the info John, that is very interesting.

Regard

Rob