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* Re: [TUHS] Spacewar at Bell Labs
@ 2020-01-15  3:32 Brian Walden
  2020-01-15  4:01 ` Jon Steinhart
  2020-01-15  6:17 ` Lars Brinkhoff
  0 siblings, 2 replies; 15+ messages in thread
From: Brian Walden @ 2020-01-15  3:32 UTC (permalink / raw)
  To: tuhs

> Papertape reader?

The last Cyphercon had a paper tape reader in their badge --

https://hackaday.com/2019/04/12/cyphercon-badge-has-a-paper-tape-reader-built-in/

You can proably buy one from the con https://cyphercon.com/, or the makers
http://www.tymkrs.com/ or ebay...

-Brian

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs
  2020-01-15  3:32 [TUHS] Spacewar at Bell Labs Brian Walden
@ 2020-01-15  4:01 ` Jon Steinhart
  2020-01-15  4:50   ` Bakul Shah
  2020-01-15  6:17 ` Lars Brinkhoff
  1 sibling, 1 reply; 15+ messages in thread
From: Jon Steinhart @ 2020-01-15  4:01 UTC (permalink / raw)
  To: tuhs

Brian Walden writes:
> > Papertape reader?
>
> The last Cyphercon had a paper tape reader in their badge --
>
> https://hackaday.com/2019/04/12/cyphercon-badge-has-a-paper-tape-reader-built-in/
>
> You can proably buy one from the con https://cyphercon.com/, or the makers
> http://www.tymkrs.com/ or ebay...
>
> -Brian

That's cool, but I'm worried about the fragility of the tape after all this time.
Maybe because I got my start in the early networking era when I had to transfer
files from one machine to another by feeding the paper tape from the punch in one
ASR-33 into the reader of another :-)

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs
  2020-01-15  4:01 ` Jon Steinhart
@ 2020-01-15  4:50   ` Bakul Shah
  0 siblings, 0 replies; 15+ messages in thread
From: Bakul Shah @ 2020-01-15  4:50 UTC (permalink / raw)
  To: Jon Steinhart; +Cc: tuhs

On Tue, 14 Jan 2020 20:01:11 -0800 Jon Steinhart <jon@fourwinds.com> wrote:
>
> That's cool, but I'm worried about the fragility of the tape after all this
> time.

I thought paper tape lasted much longer that magtapes....

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs
  2020-01-15  3:32 [TUHS] Spacewar at Bell Labs Brian Walden
  2020-01-15  4:01 ` Jon Steinhart
@ 2020-01-15  6:17 ` Lars Brinkhoff
  2020-01-15  6:34   ` Earl Baugh
  1 sibling, 1 reply; 15+ messages in thread
From: Lars Brinkhoff @ 2020-01-15  6:17 UTC (permalink / raw)
  To: Brian Walden; +Cc: tuhs

Brian Walden wrote:
>> Papertape reader?
> The last Cyphercon had a paper tape reader in their badge --
> https://hackaday.com/2019/04/12/cyphercon-badge-has-a-paper-tape-reader-built-in/

I'd be all over this if there also were a way to punch tapes.

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs
  2020-01-15  6:17 ` Lars Brinkhoff
@ 2020-01-15  6:34   ` Earl Baugh
  2020-01-15  7:10     ` [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Jon Steinhart
  2020-01-15 12:29     ` [TUHS] Spacewar at Bell Labs John Foust
  0 siblings, 2 replies; 15+ messages in thread
From: Earl Baugh @ 2020-01-15  6:34 UTC (permalink / raw)
  To: Lars Brinkhoff; +Cc: TUHS, Brian Walden

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Why not build a variation of this with an Arduino?
 https://www.instructables.com/id/DIY-Paper-TapePunch-Card-Maker-and-Reader/. You could use cardboard rather than wood if it’s just a one time job. ( or scan the tape into files and process digitally ?) 

Earl 

Sent from my iPhone

> On Jan 15, 2020, at 1:18 AM, Lars Brinkhoff <lars@nocrew.org> wrote:
> 
> Brian Walden wrote:
>>> Papertape reader?
>> The last Cyphercon had a paper tape reader in their badge --
>> https://hackaday.com/2019/04/12/cyphercon-badge-has-a-paper-tape-reader-built-in/
> 
> I'd be all over this if there also were a way to punch tapes.

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^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
  2020-01-15  6:34   ` Earl Baugh
@ 2020-01-15  7:10     ` Jon Steinhart
  2020-01-15  8:05       ` Earl Baugh
  2020-01-15 14:50       ` Clem Cole
  2020-01-15 12:29     ` [TUHS] Spacewar at Bell Labs John Foust
  1 sibling, 2 replies; 15+ messages in thread
From: Jon Steinhart @ 2020-01-15  7:10 UTC (permalink / raw)
  To: TUHS

Earl Baugh writes:
> Why not build a variation of this with an Arduino?
>  https://www.instructables.com/id/DIY-Paper-TapePunch-Card-Maker-and-Reader/.
> You could use cardboard rather than wood if it’s just a one time job. ( or scan
> the tape into files and process digitally ?) 
> 
> Earl 

I thought that I said earlier that I had a paper tape reader here but don't
remember much about it or if it ever worked.  If I didn't have a huge project
list and it wasn't ski season I could hook it up to a pi.  More likely that
I'll get to a computer museum sooner.

Just to keep this UNIX-related so that Warren doesn't get cranky, I believe
that this reader came out of some sort of experimental telephone exchange
in our group that was decommissioned.  Dave Weller was very supportive of my
interests and somehow arranged for me to take much of it home as surplus
equipment.  Kept me in 7400-series parts and Augat wire-wrap boards for a
long time.  While there was no way that I could have kept the thing, I wish
that I had the magnetic drum memory because it was so cool from an industrial
art perspective.

Heinz may remember more about this than I do because he actually worked on
this project, but our department developed what I believe was the first
all-digital telephone exchange that used digital filtering (Hal Alles and
Jim Kaiser were in the group).  I think that it had a pair of PDP-11/10s
in it, and a bigger PDP-11 as a supervisory machine that ran UNIX.  I have
vague memories of Heinz and Carl poring over huge C program listings.  I
also remember that there was a bug in the long-distance code where it wasn't
sending out the ST tone that ended up taking all of the key pulse senders in
the Berkeley Heights telephone exchange that provided the trunk line to our
lab off line as they didn't have timeouts and needed to be manually reset.
But hey, we were the phone company too so what could they do about it?

Oh, I think that the PDP-11/10s were used because we tried to use LSI-11s
but those turned out to be useless because of the way that DEC did the DRAM
refresh; it wasn't interleaved, they just stopped everything every so many
ms and refreshed everything.  Non-starter for real-time systems.

And another thought, this machine may have been why Heinz wrote MERT.

I was gone before this system was completed so I have no idea how it fared
and how many of the ideas were incorporated into production systems.  Oh,
yeah, I think that it was called the SS1 for Slave Switch 1.

Jon

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
  2020-01-15  7:10     ` [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Jon Steinhart
@ 2020-01-15  8:05       ` Earl Baugh
  2020-01-15 14:50       ` Clem Cole
  1 sibling, 0 replies; 15+ messages in thread
From: Earl Baugh @ 2020-01-15  8:05 UTC (permalink / raw)
  To: Jon Steinhart; +Cc: TUHS

I thought the concern was about the fragility of the tape and the concern about running it thru a period reader. I was just thinking these two options would be safer on the tape.  That’s why I was suggesting them.  Just trying to be helpful .. all to familiar with the long project list :-) 

Earl 


Sent from my iPhone

> On Jan 15, 2020, at 2:12 AM, Jon Steinhart <jon@fourwinds.com> wrote:
> 
> Earl Baugh writes:
>> Why not build a variation of this with an Arduino?
>> https://www.instructables.com/id/DIY-Paper-TapePunch-Card-Maker-and-Reader/.
>> You could use cardboard rather than wood if it’s just a one time job. ( or scan
>> the tape into files and process digitally ?) 
>> 
>> Earl 
> 
> I thought that I said earlier that I had a paper tape reader here but don't
> remember much about it or if it ever worked.  If I didn't have a huge project
> list and it wasn't ski season I could hook it up to a pi.  More likely that
> I'll get to a computer museum sooner.
> 
> Just to keep this UNIX-related so that Warren doesn't get cranky, I believe
> that this reader came out of some sort of experimental telephone exchange
> in our group that was decommissioned.  Dave Weller was very supportive of my
> interests and somehow arranged for me to take much of it home as surplus
> equipment.  Kept me in 7400-series parts and Augat wire-wrap boards for a
> long time.  While there was no way that I could have kept the thing, I wish
> that I had the magnetic drum memory because it was so cool from an industrial
> art perspective.
> 
> Heinz may remember more about this than I do because he actually worked on
> this project, but our department developed what I believe was the first
> all-digital telephone exchange that used digital filtering (Hal Alles and
> Jim Kaiser were in the group).  I think that it had a pair of PDP-11/10s
> in it, and a bigger PDP-11 as a supervisory machine that ran UNIX.  I have
> vague memories of Heinz and Carl poring over huge C program listings.  I
> also remember that there was a bug in the long-distance code where it wasn't
> sending out the ST tone that ended up taking all of the key pulse senders in
> the Berkeley Heights telephone exchange that provided the trunk line to our
> lab off line as they didn't have timeouts and needed to be manually reset.
> But hey, we were the phone company too so what could they do about it?
> 
> Oh, I think that the PDP-11/10s were used because we tried to use LSI-11s
> but those turned out to be useless because of the way that DEC did the DRAM
> refresh; it wasn't interleaved, they just stopped everything every so many
> ms and refreshed everything.  Non-starter for real-time systems.
> 
> And another thought, this machine may have been why Heinz wrote MERT.
> 
> I was gone before this system was completed so I have no idea how it fared
> and how many of the ideas were incorporated into production systems.  Oh,
> yeah, I think that it was called the SS1 for Slave Switch 1.
> 
> Jon

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs
  2020-01-15  6:34   ` Earl Baugh
  2020-01-15  7:10     ` [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Jon Steinhart
@ 2020-01-15 12:29     ` John Foust
  2020-01-16  0:17       ` [TUHS] tape reading (was Re: Spacewar at Bell Labs) Al Kossow
  1 sibling, 1 reply; 15+ messages in thread
From: John Foust @ 2020-01-15 12:29 UTC (permalink / raw)
  To: TUHS

At 12:34 AM 1/15/2020, Earl Baugh wrote:
>Why not build a variation of this with an Arduino?
> <https://www.instructables.com/id/DIY-Paper-TapePunch-Card-Maker-and-Reader/>https://www.instructables.com/id/DIY-Paper-TapePunch-Card-Maker-and-Reader/. You could use cardboard rather than wood if it’s just a one time job. ( or scan the tape into files and process digitally ?) 

We're so close, I wish someone would figure out a way to let
a contemporary office scanner like the Fujitsu ScanSnap to
handle paper tapes.  Reliable feed mechanism, nice scanner,
just needs a little software and maybe a guide.  And a way
to re-spool the tape.  Darn, just got complicated.  

Same thing for a new way to read a magtape.  You'd think it 
could be done with a universal read head and some software.

Nine years ago I visited <http://www.comco-inc.com/>http://www.comco-inc.com/ , perhaps
one of the last sellers and refurbishers of 9-tracks.  I dropped
off three 9-tracks I didn't need.  He seems to be surviving 
because oil survey companies still call and are willing to 
write five-figure checks for particular working hardware.

- John


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
  2020-01-15  7:10     ` [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Jon Steinhart
  2020-01-15  8:05       ` Earl Baugh
@ 2020-01-15 14:50       ` Clem Cole
  2020-01-15 23:40         ` Al Kossow
  1 sibling, 1 reply; 15+ messages in thread
From: Clem Cole @ 2020-01-15 14:50 UTC (permalink / raw)
  To: Jon Steinhart; +Cc: TUHS main list

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On Wed, Jan 15, 2020 at 2:12 AM Jon Steinhart <jon@fourwinds.com> wrote:

> we tried to use LSI-11s
> but those turned out to be useless because of the way that DEC did the DRAM
> refresh; it wasn't interleaved, they just stopped everything every so many
> ms and refreshed everything.  Non-starter for real-time systems.
>
Be careful as to who you denigrate, my friend. 😂

Very interesting history, IMO.    Yes, DEC sold the LSI-11, but Western
Digital designed it.  DEC (KO specifically) had just put Ray Ball and Ken
O'humundro's CalData out of business for cloning the PDP-11/45 with a
Unibus on his Caldata 500
<http://www.bitsavers.org/pdf/calData/CalData_Brochures_1974.pdf>.   At the
time, WD had developed and started to sell to the systems manufacturers a
new set of bit-slice chips the MCP-1600
<https://en.wikipedia.org/wiki/MCP-1600>, to compete with AMD's 2900 and
Intel 3000 series (plus they were already a chip supplier to DEC for UARTS).
   So WD designs and builds a few LSI-11 as a sales demo of what you could
do with their new bit-slice chip (*i.e. *as those things often go, the
board, bus, and memory was a quick and cheap hack).

It's important to note that the way DEC nailed CalData was the *same
instruction set on the same bus*, WD did their own bus for their demo.
Also, please remember that at the time, WD was in the chip business.   KO's
reaction this time was different.  Instead of suing, DEC got the design and
started to build and sell them.   WD took the board design, wrote a new set
of microcode based on the USCD Pascal-P machine
<https://en.wikipedia.org/wiki/UCSD_Pascal>, then sold that as a 'system'
called the Pascal MicroEngine
<https://en.wikipedia.org/wiki/Pascal_MicroEngine>, but primarily used it
is the sales demo.

I remember seeing one of the WD Pascal-P systems once when we were at Tek
(along with my favorite named workstation, the Modula based Lilith
<https://en.wikipedia.org/wiki/Lilith_(computer)>).  But I do not think the
Pascal-P (nor Lilith) was very successful.   Also, AMD ultimately won the
bit-slice chip business, as most designers at manufacturers like DEC,
Masscomp, FPS, *et al*. designed their new systems or at least the FP/AP
coprocessors with the 2900 series.

BTW: this is also why a few years later when Ken O'Humundro created another
full computer board with a 68000 on it with his new Able  Computer Corp, he
put it on the QBUS which DEC could not lock up because they did not create
it as WD had.

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^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
  2020-01-15 14:50       ` Clem Cole
@ 2020-01-15 23:40         ` Al Kossow
  0 siblings, 0 replies; 15+ messages in thread
From: Al Kossow @ 2020-01-15 23:40 UTC (permalink / raw)
  To: tuhs



On 1/15/20 6:50 AM, Clem Cole wrote:
> WD took the board design, wrote a
> new set of microcode based on the USCD Pascal-P machine <https://en.wikipedia.org/wiki/UCSD_Pascal>, then sold that as a
> 'system' called the Pascal MicroEngine <https://en.wikipedia.org/wiki/Pascal_MicroEngine>, but primarily used it is the
> sales demo.

And Volition Systems, took the P-System chip set and put it on the QBus, later put Modula-2 on it.




^ permalink raw reply	[flat|nested] 15+ messages in thread

* [TUHS] tape reading (was Re:  Spacewar at Bell Labs)
  2020-01-15 12:29     ` [TUHS] Spacewar at Bell Labs John Foust
@ 2020-01-16  0:17       ` Al Kossow
  0 siblings, 0 replies; 15+ messages in thread
From: Al Kossow @ 2020-01-16  0:17 UTC (permalink / raw)
  To: tuhs



On 1/15/20 4:29 AM, John Foust wrote:

> Same thing for a new way to read a magtape.  You'd think it 
> could be done with a universal read head and some software.

It's been done. You need a good transport that has enough torque to deal with
sticky tapes and a digitizer with about 100gigs of ram if you're doing acquisition
with a Saleae Logic16 USB3 analyzer.

https://github.com/LenShustek/readtape

The setup is a couple thousand dollars.



^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
       [not found]     ` <CAC20D2Mr1vqpoAELU3a+4cV7W99uh_76ogGQq28wktJM+onDQA@mail.gmail.com>
@ 2020-02-04 20:26       ` Dave Horsfall
  0 siblings, 0 replies; 15+ messages in thread
From: Dave Horsfall @ 2020-02-04 20:26 UTC (permalink / raw)
  To: The Eunuchs Hysterical Society

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[ Getting into COFF territory, I think ]

On Thu, 30 Jan 2020, Clem Cole wrote:

> BTW: Dave story is fun, but I think a tad apocryphal.  He's right that 
> DEC marketing was not happy about people using it, but it was well 
> spec'ed if you had CPU schematics.  They way they tried to control it 
> was to license the bus interface chips (made privately by Western 
> Digital for them IIRC but were not available on the open market).  IIRC 
> if you did not use DEC's chips, you could have issues if you >>similar<< 
> function chips from National Semi.  I remember Ken O'Munhundro giving a 
> talk at a USENIX (while he was CEO of Able) talking about 'be careful 
> with foreign UNIBUS implementations.'  If I recall it was the analog 
> characteristics that were tricky with something like the BUS acquisition 
> for DMA and Memory timing, but I admit I've forgotten the details.

Ah; the chips could explain it.  I can't remember where I heard the story, 
but it was likely in ";login:" or some place.  Hey, if the DEC marketoids 
didn't want 3rd-party UNIBUS implementations then why was it published?

> I think you are confusing VAX's SBI with UNIBUS.   With the Vax, unlike 
> PDP-11, the systems did not come with complete schematics for all 
> boards.   So to design for the SBI you had to reverse engineer the CPU 
> and Memory boards.   DEC having successfully won the CalData suit, went 
> after Systems Industries who was the first to build SBI controllers.  
>  DEC lost, but the truth was that because they had work had been reverse 
> engineering, SI was close but not 100% right and they had a number of 
> issues when the boards first hit the street, particularly with UNIX 
> which did a better job of overlapped I/O than VMS did.   At UCB we had a 
> logic analyzer in one of the 780s at all times, and the phone number of 
> the SI engineers.   We eventually helped them put out a couple ECO's 
> that make the original boards work in practice much better.

No; it was definitely UNIBUS (I wasn't aware of the SBI at the time).

As for overlapped seeks, when they were implemented in Unix it broke the 
RK-11 controller, and DEC pointed the finger at Unix (of course) since 
their own gear worked.  To cut a long story short, they were forced to use 
some fancy diagnostic (DECEX?) which hammered everything at the same time, 
and the problem showed up.  Turned out that their simpler diagnostics did 
not test for overlapped seeks, because they knew that it didn't work; out 
same the FE to modify the controller...

> BTW: My friend Dave Cane lead the BI at DEC after finishing up the 
> VAX/750 project (he had designed the SBI for 780 before that).   In 
> fact, the BI was >>supposed<< to be 'open' like Multibus and VME and all 
> chips were supposed to be from the merchant market.  But at the last 
> minute, DEC marketing refused and locked down the specs/stopped shipping 
> schematics with the new systems destined to use BI.  Dave was so pissed, 
> he left DEC to found Masscomp and design the MC500 (using the 
> Multibus).   

Yet another reason why DEC went under, I guess...

-- Dave

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
  2020-01-15 16:46 [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Noel Chiappa
  2020-01-15 18:35 ` Clem Cole
@ 2020-01-29 20:25 ` Dave Horsfall
       [not found]   ` <CABH=_VSPTV-rwu202hYuiXViiBG2ReMnshxUAvD9Lb6HqG4tQQ@mail.gmail.com>
  1 sibling, 1 reply; 15+ messages in thread
From: Dave Horsfall @ 2020-01-29 20:25 UTC (permalink / raw)
  To: The Eunuchs Hysterical Society

On Wed, 15 Jan 2020, Noel Chiappa wrote:

> Wow! WD created the QBUS? Fascinating. I wonder if DEC made any changes 
> to the QBUS between the original demo WD boards and the first DEC ones? 
> Are there any documents about the WD original still extant, do you know?

Which reminds me: I heard a story that DEC did not implement the Unibus as 
specified, in order to lock out 3rd-party vendors; apparently the timing 
was not quite right.  You couldn't complain to DEC because it was not 
their gear, and you couldn't complain to the vendor because they followed 
the spec...

-- Dave

^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
  2020-01-15 16:46 [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Noel Chiappa
@ 2020-01-15 18:35 ` Clem Cole
  2020-01-29 20:25 ` Dave Horsfall
  1 sibling, 0 replies; 15+ messages in thread
From: Clem Cole @ 2020-01-15 18:35 UTC (permalink / raw)
  To: Noel Chiappa; +Cc: TUHS main list

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On Wed, Jan 15, 2020 at 11:47 AM Noel Chiappa <jnc@mercury.lcs.mit.edu>
wrote:

> Wow! WD created the QBUS? Fascinating. I wonder if DEC made any changes to
> the
> QBUS between the original demo WD boards and the first DEC ones?

I can not say I know and I would suspect they peed on it in some manner,
that *was the DEC culture*.  I've just sent a note to Mr. BI to see if he
knows and I'll pass back anything I learn if I do.  Sounds like the sort of
thing they might have gotten changed before it was release.




> Are there any documents about the WD original still extant, do you know?
>
I'm pretty sure we had some stuff from WD at CMU, because CM* was made out
of a lot of them, and CMU did custom microcode so they could talk to the
capabilities and K.map HW.  I remember seeing some prints with WD markings
on it, but I was not heavily involved other than working the new
distributed front-end which we did with LSI-11s.

Somebody from the CMU HW lab like Jim Teter might know, although he did the
11/40e for C.mmp, I'm not sure who was the microcode guru on CM*  as that
was all happening as I was leaving.  I sent a couple of emails to folks
like Danny Klein, Mike Liebensberger, and Tron McConnell. Danny and Mike
are SW folks, Tron was a EE/HW type but mostly worked on other stuff at
Mellon Institute in those days.    But, IIRC, Tron was worked on a 3Mbit
Xerox board for the LSIs, so he might have had something.   We all did some
stuff with CM* (Mike more than any of us). FWIW: Tron was (is) a bit of
packrat and if he ever had anything like that, he might still have it.

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^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ]
@ 2020-01-15 16:46 Noel Chiappa
  2020-01-15 18:35 ` Clem Cole
  2020-01-29 20:25 ` Dave Horsfall
  0 siblings, 2 replies; 15+ messages in thread
From: Noel Chiappa @ 2020-01-15 16:46 UTC (permalink / raw)
  To: TUHS; +Cc: jnc

    > From: Clem Cole

    > So WD designs and builds a few LSI-11 as a sales demo of what you could
    > do
    > ...
    > he put it on the QBUS which DEC could not lock up because they did not
    > create it as WD had.

Wow! WD created the QBUS? Fascinating. I wonder if DEC made any changes to the
QBUS between the original demo WD boards and the first DEC ones? Are there any
documents about the WD original still extant, do you know?

(FWIW, it seems that whoever did the QBUS interrupt cycle had heard about the
metastability issues when using a flop to do the grant-passing arbitrations;
see here for more:

  https://gunkies.org/wiki/Bus_Arbitration_on_the_Unibus_and_QBUS#QBUS_Interrupts

DEC had previously bent themselves into knots trying to solve it on the UNIBUS:

  https://gunkies.org/wiki/M782_Interrupt_Control#Revisions

so it would be interesting to know if it was WD or DEC who did the DIN thing to
get rid of it on the QBUS.)

    Noel

^ permalink raw reply	[flat|nested] 15+ messages in thread

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Thread overview: 15+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-15  3:32 [TUHS] Spacewar at Bell Labs Brian Walden
2020-01-15  4:01 ` Jon Steinhart
2020-01-15  4:50   ` Bakul Shah
2020-01-15  6:17 ` Lars Brinkhoff
2020-01-15  6:34   ` Earl Baugh
2020-01-15  7:10     ` [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Jon Steinhart
2020-01-15  8:05       ` Earl Baugh
2020-01-15 14:50       ` Clem Cole
2020-01-15 23:40         ` Al Kossow
2020-01-15 12:29     ` [TUHS] Spacewar at Bell Labs John Foust
2020-01-16  0:17       ` [TUHS] tape reading (was Re: Spacewar at Bell Labs) Al Kossow
2020-01-15 16:46 [TUHS] Spacewar at Bell Labs [ really paper tape readers and tangentially related things ] Noel Chiappa
2020-01-15 18:35 ` Clem Cole
2020-01-29 20:25 ` Dave Horsfall
     [not found]   ` <CABH=_VSPTV-rwu202hYuiXViiBG2ReMnshxUAvD9Lb6HqG4tQQ@mail.gmail.com>
     [not found]     ` <CAC20D2Mr1vqpoAELU3a+4cV7W99uh_76ogGQq28wktJM+onDQA@mail.gmail.com>
2020-02-04 20:26       ` Dave Horsfall

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