Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Pontus Pihlgren]

On Tue, Mar 01, 2016 at 08:02:47AM -0500, John H. Reinhardt wrote:
> 
> On 2/29/2016 8:07 PM, Rich Alderson wrote:
> >From: David Griffith
> >Sent: Friday, February 26, 2016 4:05 PM
> >
> >>One of my ongoing wish projects is to learn to program a pdp-10 so I can
> >>port Frotz to it.
> >
> >The canonical textbook is Ralph Gorin's _Introduction to DECSYSTEM-20
> >Assembly Language Programming_ (Digital Press, 1981).  Lots of examples,
> >well thought out presentation.
> >
> 
> There is a similar document online at Columbia with parts written by Ralph 
> Gorin
> 

I think this is the same file, but in HTML-formatted with one page per 
chapter:

http://pdp10.nocrew.org/docs/instruction-set/pdp-10.html

/P

Re: cctalk Digest, Vol 20, Issue 29

[Fred]

On Mon, 29 Feb 2016 cctalk-requ...@classiccmp.org wrote:

> From: Murray McCullough 
> Subject: Techno-savvy...
> Message-ID:
>   
> Content-Type: text/plain; charset=UTF-8
>
> What is a techno-savvy student? Can classic computers possibly give an
> answer? I used early microcomputers in my electronics classroom I
> taught in the 70?s. Computers back then were rather primitive, not
> much better than calculators, but did mimic human learning ? well
[story cut]

I liked this story, reminded me of my education in the late 80's early
90's - I was the "computer go to guy" so instead of the shiny new PS/2's
the district had recently purchased they "stuck" me witth the 5150 in the
back that no one wanted to use.  The things I was able to make that thing
do with just two floppies :)

>
> So what is a techno-savvy student now: Conversant in using a
> technological gadget to enhance his/her life? Or being able to build a
> computing workstation in high school? Or for simply possessing a basic
[chop]

Whenever this comes up in the context of today's youth (where they tell me
they'll take my job one day) I just have to laugh.  The vast majority (not
all, as that would be unfair, and I have met some younger than me folks
that know their stuff) of youth today know how to USE the device, but not
necessarily how to fix it if it breaks physically or logically (I'll leave
out that fixing of these tablets/phones/pads physically is usually a board
swap ).

As Kirk said in Star Trek II, The Wrath of Khan, "You have to learn WHY
things work on a starship."

Fred

Re: cctalk Digest, Vol 20, Issue 29

[Liam Proven]

On 1 March 2016 at 14:27, Fred  wrote:
> The vast majority (not
> all, as that would be unfair, and I have met some younger than me folks
> that know their stuff) of youth today know how to USE the device, but not
> necessarily how to fix it if it breaks physically or logically


http://coding2learn.org/blog/2013/07/29/kids-cant-use-computers/

-- 
Liam Proven • Profile: http://lproven.livejournal.com/profile
Email: lpro...@cix.co.uk • GMail/G+/Twitter/Flickr/Facebook: lproven
MSN: lpro...@hotmail.com • Skype/AIM/Yahoo/LinkedIn: liamproven
Cell/Mobiles: +44 7939-087884 (UK) • +420 702 829 053 (ČR)

MM11-U G235 bias/strobe jumpers

[Noel Chiappa]

So, the MM11-U manual (EK-MF11U-MM-003) describes (pg. 3-12) a set of jumpers
(W5-W7) on the G235 card (X and Y selection line current generators - those
for the inhibit lines are on the G114) which adjust the bias current for the
selection line generators. It goes on to say:

  "Jumpers W5-W7 are factory cut to adjust the bias current to its
  optimal value and they should not be changed."

There's apparently a similar adjustment for the timing of the sense strobe
(although I can't find the description of that circuitry). So I have two
observations, based on this.


The first is that the original procedure for setting those jumpers is likely
lost, it's probably only in some internal DEC documentation. The manual says
(Section 5.4.2, "Sense Strobe Delay and Drive Current Adjustments"):

  "Correction of any failure in either the sense strobe delay or drive
  current circuits on the G235 module that would require reconfiguration
  of the jumpers within these circuits should _not_ be attempted in the
  field. Replace the faulty module with a spare G235 module and return the
  faulty G235 module to the factor for repair."

These cards are old, component values may have drifted, and so perhaps these
might need to be adjusted - but we'll need to work out a procedures for doing
so, if so.

We _do_ seem to have a test to know _if_ the bias current is properly
adjusted - see Section 5.3.4, "Drive Current Checks", and also for the strobe
delay (Section 5.3.3, "Sense Strobe Delay Checks"). So I guess in theory, if
a G235 card fails one of these tests, we could change the smallest value
jumper, and see if that made things worse or better, and then loop. So
perhaps all is not lost.


The second is that I was worried that these boards were 'tuned' to be part of
a set. E.g. one of the components, in the circuit that the W5-W7 jumpers are
part of, is a thermistor on the core stack board. I couldn't tell if the
jumpers were just for dealing with component variations on the G235 board, or
if they also include variation elsewhere - i.e. that MM11-U's came as tuned
board sets which should not be 'mix and matched'.

However, that second chunk of text I quoted alleviated that concern:
apparently one _can_ replace one G235 with another, without swapping out all
the boards in the set.

Which means that the 'mixing and matching' that has happened to these boards
since they were removed from their machines (I myself am guilty of this - I
pulled a couple of MM11-U sets, and didn't carefully keep the boards in their
original sets) has probably not caused any problems.

Noel

Re: MM11-U G235 bias/strobe jumpers

[william degnan]

On Tue, Mar 1, 2016 at 10:40 AM, Noel Chiappa 
wrote:

>
> So, the MM11-U manual (EK-MF11U-MM-003) describes (pg. 3-12) a set of
> jumpers
> (W5-W7) on the G235 card (X and Y selection line current generators - those
> for the inhibit lines are on the G114) which adjust the bias current for
> the
> selection line generators. It goes on to say:
>
>   "Jumpers W5-W7 are factory cut to adjust the bias current to its
>   optimal value and they should not be changed."
>
> There's apparently a similar adjustment for the timing of the sense strobe
> (although I can't find the description of that circuitry). So I have two
> observations, based on this.
>
>
> The first is that the original procedure for setting those jumpers is
> likely
> lost, it's probably only in some internal DEC documentation. The manual
> says
> (Section 5.4.2, "Sense Strobe Delay and Drive Current Adjustments"):
>
>   "Correction of any failure in either the sense strobe delay or drive
>   current circuits on the G235 module that would require reconfiguration
>   of the jumpers within these circuits should _not_ be attempted in the
>   field. Replace the faulty module with a spare G235 module and return the
>   faulty G235 module to the factor for repair."
>
> These cards are old, component values may have drifted, and so perhaps
> these
> might need to be adjusted - but we'll need to work out a procedures for
> doing
> so, if so.
>
> We _do_ seem to have a test to know _if_ the bias current is properly
> adjusted - see Section 5.3.4, "Drive Current Checks", and also for the
> strobe
> delay (Section 5.3.3, "Sense Strobe Delay Checks"). So I guess in theory,
> if
> a G235 card fails one of these tests, we could change the smallest value
> jumper, and see if that made things worse or better, and then loop. So
> perhaps all is not lost.
>
>
> The second is that I was worried that these boards were 'tuned' to be part
> of
> a set. E.g. one of the components, in the circuit that the W5-W7 jumpers
> are
> part of, is a thermistor on the core stack board. I couldn't tell if the
> jumpers were just for dealing with component variations on the G235 board,
> or
> if they also include variation elsewhere - i.e. that MM11-U's came as tuned
> board sets which should not be 'mix and matched'.
>
> However, that second chunk of text I quoted alleviated that concern:
> apparently one _can_ replace one G235 with another, without swapping out
> all
> the boards in the set.
>
> Which means that the 'mixing and matching' that has happened to these
> boards
> since they were removed from their machines (I myself am guilty of this - I
> pulled a couple of MM11-U sets, and didn't carefully keep the boards in
> their
> original sets) has probably not caused any problems.
>
> Noel
>


I have found (oops) that I could swap the G235's without issue, although I
had been keeping them with the rest of the core set they came with just in
case.
-- 
@ BillDeg:
Web: vintagecomputer.net
Twitter: @billdeg 
Youtube: @billdeg 
Unauthorized Bio 

RE: Needs help w/ diagnosing and hopefully repairing of a DEC Tape Drive

[tony duell]

> In my continuing quest for a 9-track drive I got my hands on DEC TSZ07-CA w/
> a narrow SCSI interface that was supposedly "tested working". On arrival to
> me I found it wrapped in a thin layer of bubble wrap w/ some broken piece of
> Styrofoam thrown in for "packing".

This looks very like a Cipher drive to me. Rather later than the F880 I've had 
in
bits on my bench recently, but some parts look very similar

The technical manual implies these are simple DC motors (the F880 ones certainly
are). It appears there are 2 connectors. One going to a cable going into the 
side of the motor (is this just 2 wires?) and one going to something on the 
bottom.
Since unlike the F880 the arm against the takeup hub is not a tachometer I am 
guessing
there is  tacho on the bottom of each motor and that's what the second cable 
connects
to.

The F880 motors just have 2 wires. When I had mine in bits I tested the motors 
by
connecting a bench supply to said wires. Those were designed to run at 30V or 
so. 
No ideas what your ones run at, but if I am right about 2 wires going into the 
motor
itself you could try applying DC between then (disconnected from the rest of 
the unit,
of course), turning up the voltage and seeing if the motor will run.

My guess is that it will. A DC motor rarely goes intermittant in the way yours 
has. It may
fail totally, it may need to be flicked by hand to get it going, but it is 
unlikely to sometimes
only make a partial turn.

My next guess is that he problem is the tachometer on the bottom of the motor. 
That, I 
assume, is how the control circuitry detects if the motor is turning in the 
self-test. If it 
doesn't get what it likes, then it will give the error. I don't know how easy 
it is to take that
apart (as my F880 doesn't have it) but it might be worth invetigating. I set up 
the F880 tacho
arm from scratch so it can't be that hard!.

It may be a good idea to remove the motor first. 

On the F880 you need a special tool to set the hub height if you take said hub 
off. I had to
make said tool (assuming my drive was initially rght). It looks as though you 
can set up this
unit without anything like that, but it is still worth measuring the height of 
the hub (in some
way) so you can get it back in the same position. 

Have you tried service aid 111? That should let you run the motors. 

It appears that error 50 is not a generic motor error, it is given as 'No 
Tachometer
phasing'. Since it suggests replacing the supply motor, I think that my guess 
that the
tacho on said motor is at fault is not a bad one :-). Of course it could be a 
problem
with the electronics it connects to, or the wiring, but you have to start 
somewhere. The
sensors in the F880 are quite simple and it didn't take me long to work out 
what to 
ecpect from them, the one on this motor may be understandable too. How many
wires does it have? If it's 3 then I would expect power, ground and signal. If 
4, then
I would expect 2 signals in quadrature to give speed and direction. I don;t 
know how
easy it is to take the motor apart (I did the ones in the F880, but they do not 
have 
tachos on the bottom) but it's got to be worth a try!

-tony

Re: Needs help w/ diagnosing and hopefully repairing of a DEC Tape Drive

[shadoooo]

Hello,
I have two TSZ07 here.
As they were sold as "for parts" obviously they both needed some repair.

One of the two had severe mechanical problems.
One motor had a loose unglued magnet inside, so there was a motor fault 
error, and the motor couldn't rotate freely,

making a rattle noise inside when operated by hand.
Of course it was better not to act on that before repair, to avoid to 
damage the magnet.
To repair it I needed to unscrew the reel (in my case the front reel 
with the loading mechanism to
hold the interchangeable reel with the tape), unscrew the motor from the 
frame, then remove the tacho (very delicate!)

and then finally open the motor.
The loose magnet appeared to be originally glued to the metal housing 
with cyanoacrilic glue, so I positioned it by hand
aligning it with the remaining glue traces on the housing, held it in 
place with a clamp tool then finally added new abundant glue all around, 
letting it to flow under the magnet. Then waited for 24 hours and 
reassembled.
The tacho wheel needed to be cleaned, as the very thin steel growth with 
some oxide in the small holes,

not being optically open enough to work.
You can see how this wheel is delicate... maximum care not to bend or 
crack it!


It worked!

PS= check very carefully your PSU, as both drives had severe problems on 
it, they are very prone to fail!
One simply ceased to operate after some time, and needed some component 
replacement to work again.
The second one did worst! It did fail beginning suddenly to put out 
pulsed voltage (8-10V peak) on the 5V.
I turned it off within a couple of seconds, but unluckly it fried some 
ICs on the digital board...

It had to change two Z80-serie ICs on the board, to let it finally work...
And of course to repair the PSU and test it for some hours with load 
before testing it again with the real hardware.


Andrea

Re: Precision Instruments PI1200 7 track tape drive, interest anyone?

[Gerry Schlosser]

Hello Mattis,



We do have interest in the 7 track drive. Is it still available?



Gerry Schlosser



Absolute Imaging Inc.

Suite 400, 1011-1st Street S.W.

Calgary, Alberta, Canada

T2R 1J2



ge...@absoluteimaging.ca

1-403-209-6846

RE: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Rich Alderson]

From: Glen Slick
Sent: Monday, February 29, 2016 7:43 PM

> On Feb 29, 2016 5:07 PM, "Rich Alderson" 
> wrote:

>> From: David Griffith
>> Sent: Friday, February 26, 2016 4:05 PM

>>> One of my ongoing wish projects is to learn to program a pdp-10 so I can
>>> port Frotz to it.

>> The canonical textbook is Ralph Gorin's _Introduction to DECSYSTEM-20
>> Assembly Language Programming_ (Digital Press, 1981).  Lots of examples,
>> well thought out presentation.

>> It's a shame that Ralph's book has become so rare.  (Seriously, who
>> does the seller asking $1,441.25 for a copy think he's talking to???)
>> Probably remaindered in the 1990s at any library that had a copy.

> FWIW Amazon lists used copies of ISBN-13 978-0932376121 around $100. I
> bought a used copy a couple of years ago that turned out to be an
> ex-library copy. Don't think I paid too much at the time. Still haven't
> gotten around to looking at it much.

For most hobbyists, even $100 is too much.  I was simply astounded at the
chutzpah of the seller--right there on the Amazon list--who was asking
nearly $1500 for a copy.


From: Mark Wickens
Sent: Monday, February 29, 2016 11:32 PM

> There is a copy on archive.org: 
> https://archive.org/details/introductiontode00step

Well, I was going to point that out to my friend Ralph, but I see that
it is a different book with the same title, by one Stephen Longo, which
has been stolen.


From: John H. Reinhardt
Sent: Tuesday, March 01, 2016 5:03 AM

> There is a similar document online at Columbia with parts written by
> Ralph Gorin

> 

Rather, adapted from Ralph's early course notes (he was teaching the
class at Stanford for a few years before the book was published) by
Frank da Cruz and Chris Ryland.  I know that Frank and Ralph were
friendly, so I'm not surprised that Ralph shared his notes.


From: Pontus Pihlgren
Sent: Tuesday, March 01, 2016 5:13 AM

On Tue, Mar 01, 2016 at 08:02:47AM -0500, John H. Reinhardt wrote:

>> 

> I think this is the same file, but in HTML-formatted with one page per
> chapter:

> http://pdp10.nocrew.org/docs/instruction-set/pdp-10.html

No, that's an HTMLized version of the INFO file that accompanies the
original EMACS (the one written in MIT AI Lab TECO for the PDP-10).


So David, there are alternatives to the Gorin textbook.  I simply prefer
it for paedogogical reasons.


Rich


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134

mailto:ri...@livingcomputermuseum.org

http://www.LivingComputerMuseum.org/

Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Sean Conner]

It was thus said that the Great Rich Alderson once stated:
> 
> For most hobbyists, even $100 is too much.  I was simply astounded at the
> chutzpah of the seller--right there on the Amazon list--who was asking
> nearly $1500 for a copy.

  I think that comes from an unchecked computer algorithm, not simple greed.
I think what's happening here is someone (some Amazon third party) offered
the book for, say, $5.  Another third party scans Amazon for such books, and
offers it for say, $6, with the hope that you (the potential buyer) will
only see their their offer for $6 and buy from them, at which point they
will buy it for $5 from the original seller, sell it to you for $6 and
pocket the $1 profit.  The problem comes when a third third-party seller
sees the offer for $6 and does the same thing as the second one, only now
they're offering it for $7, will pay $6 for it and pocket $1 profit.

  Keep repeating that process and you end up with books selling for $1500.

  -spc (Who knows?  If you keep searching, you might find the original
seller selling it for $5 ... )

Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Brent Hilpert]

On 2016-Mar-01, at 4:36 PM, Sean Conner wrote:
> It was thus said that the Great Rich Alderson once stated:
>> 
>> For most hobbyists, even $100 is too much.  I was simply astounded at the
>> chutzpah of the seller--right there on the Amazon list--who was asking
>> nearly $1500 for a copy.
> 
>  I think that comes from an unchecked computer algorithm, not simple greed.
> I think what's happening here is someone (some Amazon third party) offered
> the book for, say, $5.  Another third party scans Amazon for such books, and
> offers it for say, $6, with the hope that you (the potential buyer) will
> only see their their offer for $6 and buy from them, at which point they
> will buy it for $5 from the original seller, sell it to you for $6 and
> pocket the $1 profit.  The problem comes when a third third-party seller
> sees the offer for $6 and does the same thing as the second one, only now
> they're offering it for $7, will pay $6 for it and pocket $1 profit.
> 
>  Keep repeating that process and you end up with books selling for $1500.
> 
>  -spc (Who knows?  If you keep searching, you might find the original
>   seller selling it for $5 ... )


For example:

http://www.digitaltrends.com/computing/why-did-amazon-charge-23698655-93-for-a-textbook/
I've come across other articles about this in the past. Don't know the 
specifics of the book mentioned by Rich.

Algorithmic pricing gone critical - Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Toby Thain]

On 2016-03-01 7:36 PM, Sean Conner wrote:

It was thus said that the Great Rich Alderson once stated:


For most hobbyists, even $100 is too much.  I was simply astounded at the
chutzpah of the seller--right there on the Amazon list--who was asking
nearly $1500 for a copy.


   I think that comes from an unchecked computer algorithm, not simple greed.
I think what's happening here is someone (some Amazon third party) offered
the book for, say, $5.  Another third party scans Amazon for such books, and
offers it for say, $6, with the hope that you (the potential buyer) will
only see their their offer for $6 and buy from them, at which point they
will buy it for $5 from the original seller, sell it to you for $6 and
pocket the $1 profit.  The problem comes when a third third-party seller
sees the offer for $6 and does the same thing as the second one, only now
they're offering it for $7, will pay $6 for it and pocket $1 profit.

   Keep repeating that process and you end up with books selling for $1500.


Or more:
http://www.michaeleisen.org/blog/?p=358
etc.

Remind me why HFT is a great idea...



   -spc (Who knows?  If you keep searching, you might find the original
seller selling it for $5 ... )

Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Ian S. King]

On Tue, Mar 1, 2016 at 5:11 PM, Brent Hilpert  wrote:

> On 2016-Mar-01, at 4:36 PM, Sean Conner wrote:
> > It was thus said that the Great Rich Alderson once stated:
> >>
> >> For most hobbyists, even $100 is too much.  I was simply astounded at
> the
> >> chutzpah of the seller--right there on the Amazon list--who was asking
> >> nearly $1500 for a copy.
> >
> >  I think that comes from an unchecked computer algorithm, not simple
> greed.
> > I think what's happening here is someone (some Amazon third party)
> offered
> > the book for, say, $5.  Another third party scans Amazon for such books,
> and
> > offers it for say, $6, with the hope that you (the potential buyer) will
> > only see their their offer for $6 and buy from them, at which point they
> > will buy it for $5 from the original seller, sell it to you for $6 and
> > pocket the $1 profit.  The problem comes when a third third-party seller
> > sees the offer for $6 and does the same thing as the second one, only now
> > they're offering it for $7, will pay $6 for it and pocket $1 profit.
> >
> >  Keep repeating that process and you end up with books selling for $1500.
> >
> >  -spc (Who knows?  If you keep searching, you might find the original
> >   seller selling it for $5 ... )
>
>
> For example:
>
> http://www.digitaltrends.com/computing/why-did-amazon-charge-23698655-93-for-a-textbook/
> I've come across other articles about this in the past. Don't know the
> specifics of the book mentioned by Rich.
>
>
On abebooks.com, the lowest price is right around $100 with shipping.  Yes,
this sucks.  Yes, this is how capitalism works.  :-)  I've paid serious
money for books that are relevant to my research that aren't available in
libraries - one of them was no closer than Paris.  (I bought it from India
for about $50, and I won't loan it out.)

-- 
Ian S. King, MSIS, MSCS, Ph.D. Candidate
The Information School 
Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical
Narrative Through a Design Lens

Archivist, Voices From the Rwanda Tribunal 
Value Sensitive Design Research Lab 

University of Washington

There is an old Vulcan saying: "Only Nixon could go to China."

RE: Needs help w/ diagnosing and hopefully repairing of a DEC Tape Drive

[Ali]

Shad and Tony,

Thank you very much for the information and advice. I spoke further to the
seller and he wants the broken drive back. As there is no guarantee I can
fix this I am going to return the drive to the seller.

-Ali

Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[Alan Perry]

I loaned Rich my big bag of DECsystem-20 docs, including the Gorin book, from 
my days as a systems programmer on a couple of -20s in college. Guess I should 
have taken a deposit or some ID ;)

I had some time to kill in SoDo and went to LCM for the first since it opened 
to the public. I tried to say 'hi' to Rich and instead got my bag of DEC stuff 
back. Didn't really need it back then.

I had been asking Rich about the stuff because I had been trying to get some 
other docs back from another museum and they couldn't find them. I just wanted 
to make sure Rich knew where my -20 stuff was. Oh well.

I was one of the first outside people to get an account on LCM's Toad, but one 
day I found my account was gone, so I have been doing -20 work on SIMH since 
then.

alan

> On Mar 1, 2016, at 17:40, Ian S. King  wrote:
> 
>> On Tue, Mar 1, 2016 at 5:11 PM, Brent Hilpert  wrote:
>> 
>>> On 2016-Mar-01, at 4:36 PM, Sean Conner wrote:
>>> It was thus said that the Great Rich Alderson once stated:
 
 For most hobbyists, even $100 is too much.  I was simply astounded at
>> the
 chutzpah of the seller--right there on the Amazon list--who was asking
 nearly $1500 for a copy.
>>> 
>>> I think that comes from an unchecked computer algorithm, not simple
>> greed.
>>> I think what's happening here is someone (some Amazon third party)
>> offered
>>> the book for, say, $5.  Another third party scans Amazon for such books,
>> and
>>> offers it for say, $6, with the hope that you (the potential buyer) will
>>> only see their their offer for $6 and buy from them, at which point they
>>> will buy it for $5 from the original seller, sell it to you for $6 and
>>> pocket the $1 profit.  The problem comes when a third third-party seller
>>> sees the offer for $6 and does the same thing as the second one, only now
>>> they're offering it for $7, will pay $6 for it and pocket $1 profit.
>>> 
>>> Keep repeating that process and you end up with books selling for $1500.
>>> 
>>> -spc (Who knows?  If you keep searching, you might find the original
>>>  seller selling it for $5 ... )
>> 
>> 
>> For example:
>> 
>> http://www.digitaltrends.com/computing/why-did-amazon-charge-23698655-93-for-a-textbook/
>> I've come across other articles about this in the past. Don't know the
>> specifics of the book mentioned by Rich.
> On abebooks.com, the lowest price is right around $100 with shipping.  Yes,
> this sucks.  Yes, this is how capitalism works.  :-)  I've paid serious
> money for books that are relevant to my research that aren't available in
> libraries - one of them was no closer than Paris.  (I bought it from India
> for about $50, and I won't loan it out.)
> 
> -- 
> Ian S. King, MSIS, MSCS, Ph.D. Candidate
> The Information School 
> Dissertation: "Why the Conversation Mattered: Constructing a Sociotechnical
> Narrative Through a Design Lens
> 
> Archivist, Voices From the Rwanda Tribunal 
> Value Sensitive Design Research Lab 
> 
> University of Washington
> 
> There is an old Vulcan saying: "Only Nixon could go to China."

Re: Algorithmic pricing gone critical - Re: PDP-10 programming [was RE: Dumb Terminal games (was Re: Looking for a small fast VAX development machine)]

[william degnan]

On Mar 1, 2016 8:19 PM, "Toby Thain"  wrote:
>
> On 2016-03-01 7:36 PM, Sean Conner wrote:
>>
>> It was thus said that the Great Rich Alderson once stated:
>>>
>>>
>>> For most hobbyists, even $100 is too much.  I was simply astounded at
the
>>> chutzpah of the seller--right there on the Amazon list--who was asking
>>> nearly $1500 for a copy.
>>
>>
>>I think that comes from an unchecked computer algorithm, not simple
greed.
>> I think what's happening here is someone (some Amazon third party)
offered
>> the book for, say, $5.  Another third party scans Amazon for such books,
and
>> offers it for say, $6, with the hope that you (the potential buyer) will
>> only see their their offer for $6 and buy from them, at which point they
>> will buy it for $5 from the original seller, sell it to you for $6 and
>> pocket the $1 profit.  The problem comes when a third third-party seller
>> sees the offer for $6 and does the same thing as the second one, only now
>> they're offering it for $7, will pay $6 for it and pocket $1 profit.
>>
>>Keep repeating that process and you end up with books selling for
$1500.
>
>
> Or more:
> http://www.michaeleisen.org/blog/?p=358
> etc.
>
> Remind me why HFT is a great idea...
>
>>
>>-spc (Who knows?  If you keep searching, you might find the original
>> seller selling it for $5 ... )
>>
>

I would think pdp 10 original books / manuals are hard to find.

Random VGA question: 160x200 "high color" mode?

[Josh Dersch]

Awhile back a "pre-alpha" version of the PC classic "DOOM" was unearthed 
(dated Feb 28, 1993), and it claims to support a "high color" VGA mode.  

From the README.TXT:


"Use High-color DAC (160 x200, but great color!)
(Only newer VGA cards have this-if it looks OK, ya got it)
(This may--okay, will--REALLY screw up the playscreen's
 graphics.  Just look at the neat colors and don't worry.)"

I've tried it on a number of machines (from the 386 era to a modern PC) 
and they all just end up showing garbage when this mode is enabled.  I 
cannot for the life of me find a reference to this mode existing 
anywhere, but I assume it must have worked on *some* SVGA chipset of the 
era since ID programmed in support for it.  I'm guessing it was cut 
because nothing else supported it (and because 160x200 must have looked 
awful, even with lots of colors...)


Does this odd video mode ring any bells with anyone out there?  Any idea 
what hardware to look for that might support it?  At this point I'm more 
curious about the actual hardware than getting this pre-alpha to run 
with it...


- Josh

Re: PDP-11/20 vd one that just says pdp 11 what are the date differences?? OEM?

[Michael Thompson]

>
> Date: Fri, 26 Feb 2016 07:21:13 -0500 (EST)
> From: j...@mercury.lcs.mit.edu (Noel Chiappa)
> Subject: Re: PDP-11/20 vd one that just says pdp 11 what are the date
> differences?? OEM?
>
> That's an -11/15, then. The -11/20 has a KA11 processor. So the front panel
> just says "pdp-11"?
>
> Noel
>

It was an OEM system and has a Applied Color Systems, Inc. front panel.
The system is missing all of the boards and backplanes.
Someday we will find enough parts to put it back together.

-- 
Michael Thompson