26 May
2014
26 May
'14
2:35 p.m.
I watched about 3 minutes. Pure garbage.
Halt and Catch Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
No one looked, acted, or talked like that back in the early 1980s (I
remember, I was there). Especially not IBM sales people.
If you could find a chick anywhere that looked 1/4 as cute as the chick in
the opening scene and who knew as much about computers, you were either in
the future, watching a bad 2014 television drama, or you were someplace
private by yourself with your pants down lost in your imagination.
I'm sure I could come up with more criticisms if I could deaden my senses
enough without taking out critical life functions to watch the rest.
Unfortunately, this program was designed for the braindead, technically
illiterate cultural group that comprises television watchers generally.
Whoever wrote this knows a computer collector. However, based on the
level of comprehension of the subject matter that gets incorporated into
the script, the writer probably only likes the computer collector in as
much as they can get fodder for their crappy TV scripts.
If any Hollywood people are reading this and want to make a good
historical computer based drama or movie (it's been all downhill since War
Games), you know how to contact me.
--
Sellam ibn Abraham VintageTech
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintagetech.com
Whatsoever a man soweth, that shall he also reap. The truth is always simple.
* * * NOTICE * * *
Due to the insecure nature of the medium over which this message has
been transmitted, no statement made in this writing may be considered
reliable for any purpose either express or implied. The contents of
this message are appropriate for entertainment and/or informational
purposes only. The right of the people to be secure in their papers
against unreasonable searches and seizures shall not be violated.
26 May
26 May
5:04 p.m.
On 05/26/2014 11:35 AM, Sellam ibn Abraham wrote:
I watched about 3 minutes. Pure garbage.
Halt and Catch Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
This reminds me that I'm not missing anything by not having cable. Ted
Sturgeon really did have it right.
--Chuck
5:24 p.m.
Those shows are for entertainment and not to be 100% historically accurate.
-----Original Message-----
From: Chuck Guzis
Sent: Monday, May 26, 2014 5:04 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Catch and Halt Fire - Drama set in early days of personal
computing
This reminds me that I'm not missing anything by not having cable. Ted
Sturgeon really did have it right.
--Chuck
---
This email is free from viruses and malware because avast! Antivirus protection is
active.
http://www.avast.com
5:58 p.m.
On May 26, 2014, at 17:24, "TeoZ" <teoz at neo.rr.com> wrote:
Those shows are for entertainment and not to be 100% historically accurate.
Indeed not, but there's a line between "not 100% accurate"
and "appallingly bad". Everything I've heard about HCF since
its release has tended towards the latter, which is somewhat
disappointing given the relative obscurity of the name. I
will admit to having gotten my hopes up, though I also do
not have cable, so it would have been somewhat academic
until it came out on Netflix.
- Dave
27 May
27 May
2:11 p.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
Those shows are for entertainment and not to be 100% historically accurate.
In my case (and I suspect for others here), having a TV programme or film
which is technically very inaccurate means it is no longer entertaining.
It is, in fact, quite unpleasant to watch.
I suspect it's like listening to a piece of music played by out-of-tune
instruments,
-tony
3:30 p.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
On Tue, 27 May 2014, Tony Duell wrote:
I had seen worse. I'll probably watch it for something to mentally
critique. Usually I watch stuff that makes me think...this can be
relaxing without as dull as intentionally dumb humour.
Those shows are for entertainment and not to be 100% historically accurate.
In my case (and I suspect for others here), having a TV programme or film
which is technically very inaccurate means it is no longer entertaining.
It is, in fact, quite unpleasant to watch.
I suspect it's like listening to a piece of music
played by out-of-tune
instruments,
-tony
--
Cory Smelosky
http://gewt.net Personal stuff
http://gimme-sympathy.org Projects
3:32 p.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
On May 27, 2014, at 11:11 AM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
In my case (and I suspect for others here), having a
TV programme or film
which is technically very inaccurate means it is no longer entertaining.
It is, in fact, quite unpleasant to watch.
I suspect it's like listening to a piece of music played by out-of-tune
instruments,
I watched it and was annoyed with their ridiculous ideas of tech, but at this point
I'm more interested in seeing how they explain how they think copyright works.
3 Jun
3 Jun
11:47 a.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
Wait a minute.
I thought we were discussing Catch and Halt Fire: the gritty new crime
drama (on FX) where the chief inspector tries to stop a city wide arsonist.
Only to find out it was his son all long!
Sorry for the spoiler.
--
tim lindner
27 May
27 May
7:20 p.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
This is nothing particularly new. I remember watching movies and TV shows that displayed
tap drives as 'computers'.
Not to mention having them 'blow up real good' when something was thrown at them.
Just realize that every specialist is likely to find something wrong in media created by
people unfamiliar with their speciality, be it computers, aircraft or plumbing.
In some ways, the Star Trek movie scene in which (I believe) Scotty talked into a mouse
was a direct (and funny) poke at the issue.
----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: cctalk at classiccmp.org
Sent: Tuesday, May 27, 2014 11:11:37 AM
Subject: Re: Catch and Halt Fire - Drama set in early days of personal
Those shows are for entertainment and not to be 100% historically accurate.
In my case (and I suspect for others here), having a TV programme or film
which is technically very inaccurate means it is no longer entertaining.
It is, in fact, quite unpleasant to watch.
I suspect it's like listening to a piece of music played by out-of-tune
instruments,
-tony
26 May
26 May
5:48 p.m.
On 27/05/2014 6:35 a.m., Sellam ibn Abraham wrote:
I watched about 3 minutes. Pure garbage.
One important thing to keep in mind is that it's a fictional TV drama.
But unlike Greys Anatomy, we get to see 1980's computer gear in the
background, which I think is brilliant.
If you weren't a vintage enthusiast, you wouldn't notice the issues, and
that is most of the population. I'm just glad I have a show to watch
with my partner, that involves my hobby, and we can both enjoy.
6:12 p.m.
On 5/26/2014 11:35 AM, Sellam ibn Abraham wrote:
If you could find a chick anywhere that looked 1/4 as cute as the chick in
the opening scene and who knew as much about computers, you were either in
the future, watching a bad 2014 television drama, or you were someplace
private by yourself with your pants down lost in your imagination.
Yes, it's insane to think that someone could be intelligent *and* female
*and* have fashion sense at the same time.
God forbid, especially in this industry.
If any Hollywood people are reading this and want to make a good
historical computer based drama or movie (it's been all downhill since War
Games), you know how to contact me.
Can you also provide them some period-correct women objects?
- Josh
9:31 p.m.
I viewed the first episode on YouTube.
Yes, there were cliches that just didn't ring true and were tailored to a
modern audience. The punk in-your-face, anti-everything, kick-ass (but
brilliant programmer and stunning to boot) girl for example. Pure
hollywood, drawing on Girl with the Dragon Tattoo and Tank Girl. Maybe I
had a sheltered life but I never met anyone like that in the early 80s.
One the other hand, some things struck a chord. The reluctant engineer who
had tried to introduce his own computer and failed yet still had that
dream. He was very reluctant to risk all and put his family through all
that again. He was believable. The early 80s was a time of incredible
opportunity in personal computing and also a period of incredible change.
Small companies were going bust all the time. I bet there was a lot of
people who were just like him. As a character then he seemed believable
(although I'm not sure I would put up with the way he was bullied by the
main protagonist).
As to our main guy, well...Steve Jobs seemed to be someone with the same
kind of determination, arrogance and self-belief. So maybe these
characters were around.
Some details were fiction...like the necessity of bios detection and
decoding as others have said. Also, I too heard a hard disk drive spin up
on that floppies only TRS-80 Model 4.
However, on balance I enjoyed it. If you take it for what it is...a
fictional drama for 2014 audiences, about opportunities in those turbulent
years when personal computers went mainstream, then comes near the mark.
I particularly enjoyed the ending when that army of IBM suits filed in.
Sure, it may have been Hollywood license on a perception but it did create
that David and Goliath tension that drama so loves.
I'm looking forward to when the series plays here.
Terry (Tez)
27 May
27 May
2:03 a.m.
On Mon, May 26, 2014 at 4:12 PM, Josh Dersch <derschjo at gmail.com> wrote:
Yes, it's insane to think that someone could be
intelligent *and* female
*and* have fashion sense at the same time.
God forbid, especially in this industry.
I'm reasonably certain that Sellam was talking about how things *actually*
were back in the early 1980s, not how they should have been, or how they
might be now, or how we might want the early 1980s portrayed in 21st
century television programs.
As with most generalizations, perhaps Sellam's wasn't 100% accurate, but it
was damn close. Unfortunately.
3:05 a.m.
On 5/26/2014 11:03 PM, Eric Smith wrote:
On Mon, May 26, 2014 at 4:12 PM, Josh Dersch
<derschjo at gmail.com> wrote:
I've no doubt that women were in the minority in the computer biz in the
1980s (as they remain today). I do take umbrage with Sellam's
supposition that there were no women at all with technical knowledge (or
if there were, they were all apparently ugly) -- this is demonstrably
untrue and it seems an odd point to bring up as a criticism of the show
(I mean, it has so many other flaws that he didn't even see, since he
admits to only watching 3 minutes of it...). Were there are lot of
women in the industry? No. Does the show have a woman in it? Yep. Is
this particularly unrealistic? Nah.
(Really, I'd like to give the show a chance; I feel like I'm
experiencing what every doctor or lawyer goes through when watching a
medical or legal drama on TV or in the theater...)
At any rate, just me spouting off my mouth when I ought best have said
nothing at all :).
- Josh
Yes, it's insane to think that someone could
be intelligent *and* female
*and* have fashion sense at the same time.
God forbid, especially in this industry.
I'm reasonably certain that Sellam was talking about how things *actually*
were back in the early 1980s, not how they should have been, or how they
might be now, or how we might want the early 1980s portrayed in 21st
century television programs.
As with most generalizations, perhaps Sellam's wasn't 100% accurate, but it
was damn close. Unfortunately.
6 a.m.
>>>
I've no doubt that women were in the minority in the computer biz in the
1980s (as they remain today). I do take umbrage with Sellam's supposition
that there were no women at all with technical knowledge (or if there were,
they were all apparently ugly) -- this is demonstrably untrue and it seems
an odd point to bring up as a criticism <<<<0/7522 - Release Date: 05/19/14
Internal Virus Database is out of date.
<<<<
In the 1960s/early 1970s there was quite a high proportion of women in
programming/systems analysis/management, a fair number in operations (though
there was some doubt about employing women on night shifts), and, of course,
almost all data-prepartion staff (I don't think we ever saw a woman in
(hardware) maintenance and very few in sales (other than the photos in
brochures).
This was two-fold in reason:
We needed all the competent staff we could get
There was no "glass ceiling"
OK, by the '80s this was changing but there were still plenty of intelligent
and good-looking women in the business. It may well be that those who were
intelligent enough for deep technical roles were too intelligent to waste
time and money on "fashion".
Andy (I remember the 60s so I obviously couldn't have been there)
8:25 a.m.
On Tue, May 27, 2014 at 1:05 AM, Josh Dersch <derschjo at gmail.com> wrote:
I've no doubt that women were in the minority in
the computer biz in the
1980s (as they remain today). I do take umbrage with Sellam's supposition
that there were no women at all with technical knowledge (or if there were,
they were all apparently ugly) -- this is demonstrably untrue and it seems
an odd point to bring up as a criticism of the show (I mean, it has so many
other flaws that he didn't even see, since he admits to only watching 3
minutes of it...). Were there are lot of women in the industry? No. Does
the show have a woman in it? Yep. Is this particularly unrealistic? Nah.
I imagine that he'd admit that the actual number was non-zero. But to a
first approximation, it was zero.
10:23 a.m.
I just see it as a fictional story. Turn the brain off and get some fun :)
Of course I'd love to see a period-correct story, but where would be all
the fun for normal people beside us, nerds?
On Tue, May 27, 2014 at 9:25 AM, Eric Smith <spacewar at gmail.com> wrote:
On Tue, May 27, 2014 at 1:05 AM, Josh Dersch
<derschjo at gmail.com> wrote:
I imagine that he'd admit that the actual number was non-zero. But to a
first approximation, it was zero.
I've no doubt that women were in the minority
in the computer biz in the
1980s (as they remain today). I do take umbrage with Sellam's
supposition
that there were no women at all with technical
knowledge (or if there
were,
they were all apparently ugly) -- this is
demonstrably untrue and it
seems
an odd point to bring up as a criticism of the
show (I mean, it has so
many
other flaws that he didn't even see, since he
admits to only watching 3
minutes of it...). Were there are lot of women in the industry? No.
Does
the show have a woman in it? Yep. Is this
particularly unrealistic?
Nah.
28 May
28 May
11:04 a.m.
On May 27, 2014, at 12:05 AM, Josh Dersch <derschjo at gmail.com> wrote:
On 5/26/2014 11:03 PM, Eric Smith wrote:
That really doesn't track with my experiences. While in school (mid-late 70's)
there were a fair number of women in my EE classes (not to mention the other engineering
disciplines). Was it 50%? No. But they were hardly token numbers and some of them were
at the top of the class and while this may come across as somewhat sexist, they
weren't bad looking.
Also, my experiences in the late 70's early 80's w.r.t. women in the computer
industry was that there weren't token numbers either (at least at IBM). They were
working side-by-side with "us guys" and could definitely hold their own.
TTFN - Guy
On Mon, May 26, 2014 at 4:12 PM, Josh Dersch
<derschjo at gmail.com> wrote:
I've no doubt that women were in the minority in the computer biz in the 1980s (as
they remain today). I do take umbrage with Sellam's supposition that there were no
women at all with technical knowledge (or if there were, they were all apparently ugly) --
this is demonstrably untrue and it seems an odd point to bring up as a criticism of the
show (I mean, it has so many other flaws that he didn't even see, since he admits to
only watching 3 minutes of it...). Were there are lot of women in the industry? No. Does
the show have a woman in it? Yep. Is this particularly unrealistic? Nah.
(Really, I'd like to give the show a chance; I feel like I'm experiencing what
every doctor or lawyer goes through when watching a medical or legal drama on TV or in the
theater...)
At any rate, just me spouting off my mouth when I ought best have said nothing at all
:).
- Josh
>
> As with most generalizations, perhaps Sellam's wasn't 100% accurate, but it
> was damn close. Unfortunately. Yes, it's insane to think that someone could
be intelligent *and* female
*and* have fashion sense at the same time.
God forbid, especially in this industry.
I'm reasonably certain that Sellam was talking about how things *actually*
were back in the early 1980s, not how they should have been, or how they
might be now, or how we might want the early 1980s portrayed in 21st
century television programs. 
27 May
27 May
12:37 p.m.
On 27/05/2014 07:03, Eric Smith wrote:
On Mon, May 26, 2014 at 4:12 PM, Josh Dersch
<derschjo at gmail.com> wrote:
I haven't seen this but wonder how you assess fashion sense in an
historical perspective. A quick browse round the Newcastle 40th
Anniversary site
http://history.cs.ncl.ac.uk/anniversaries/40th/webbook/contents.html
shows there were significant numbers of female persons involved, and
many had intelligence, and possibly "fashion sense", but how can geeks
like us comment on what is or is not fashion sense. They were perhaps in
the minority, but a significant minority.
Mind I do remember being astounded watching one of our key-to-disk girls
keying with 2" finger nails... I think @ 20K key depressions per hour....
Dave
G4UGM
--
Dave
G4UGM
Yes, it's insane to think that someone could
be intelligent *and* female
*and* have fashion sense at the same time.
God forbid, especially in this industry.
I'm reasonably certain that Sellam was talking about how things *actually*
were back in the early 1980s, not how they should have been, or how they
might be now, or how we might want the early 1980s portrayed in 21st
century television programs.
As with most generalizations, perhaps Sellam's wasn't 100% accurate, but it
was damn close. Unfortunately. 
26 May
26 May
6:45 p.m.
Me, from Facebook:
Imagine watching a medieval based show and you are an expert on medieval
times.
Either you can go insane that a 14th century broadsword is being carried by
an obvious cleric in the 8th century-evident homes, or you can really get
into what Vestivus is doing to keep the conflict between Harvarn and
Polemar from destroying the kingdom.
On Mon, May 26, 2014 at 2:35 PM, Sellam ibn Abraham
<sellam at vintagetech.com>wrote:
I watched about 3 minutes. Pure garbage.
Halt and Catch Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
No one looked, acted, or talked like that back in the early 1980s (I
remember, I was there). Especially not IBM sales people.
If you could find a chick anywhere that looked 1/4 as cute as the chick in
the opening scene and who knew as much about computers, you were either in
the future, watching a bad 2014 television drama, or you were someplace
private by yourself with your pants down lost in your imagination.
I'm sure I could come up with more criticisms if I could deaden my senses
enough without taking out critical life functions to watch the rest.
Unfortunately, this program was designed for the braindead, technically
illiterate cultural group that comprises television watchers generally.
Whoever wrote this knows a computer collector. However, based on the
level of comprehension of the subject matter that gets incorporated into
the script, the writer probably only likes the computer collector in as
much as they can get fodder for their crappy TV scripts.
If any Hollywood people are reading this and want to make a good
historical computer based drama or movie (it's been all downhill since War
Games), you know how to contact me.
--
Sellam ibn Abraham
VintageTech
------------------------------------------------------------------------------
International Man of Intrigue and Danger
http://www.vintagetech.com
Whatsoever a man soweth, that shall he also reap. The truth is always
simple.
* * * NOTICE * * *
Due to the insecure nature of the medium over which this message has
been transmitted, no statement made in this writing may be considered
reliable for any purpose either express or implied. The contents of
this message are appropriate for entertainment and/or informational
purposes only. The right of the people to be secure in their papers
against unreasonable searches and seizures shall not be violated.
27 May
27 May
2:08 p.m.
Halt and Catch Fire is not a real computer instruction
that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
I thought there was at least one microprocessor (Motorola 6800?) where an
undocumented instruction would cause the processor to simply do memory
cycles at the fasted posible rate, address incrementing each time, and
the procesosr ignored all inputs apart from reset.
While the machine did not catch fire, the system was essentailly locked
up until the hardware reset.
-tony
4:15 p.m.
-----Oorspronkelijk bericht-----
From: Tony Duell
Sent: Tuesday, May 27, 2014 8:08 PM
To: cctalk at classiccmp.org
Subject: Re: Catch and Halt Fire - Drama set in early days of personal
computing
Halt and Catch Fire is not a real computer instruction
that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
I thought there was at least one microprocessor (Motorola 6800?) where an
undocumented instruction would cause the processor to simply do memory
cycles at the fasted posible rate, address incrementing each time, and
the procesosr ignored all inputs apart from reset.
While the machine did not catch fire, the system was essentailly locked
up until the hardware reset.
-tony
As usual, Tony is correct.
I remember that the 6800 has an undocumented (illegal) opcode
that did cycle through all addresses at clock speed. IIRC, it was also
mentioned in a BYTE article (when BYTE was still a joy to read).
- Henk
28 May
28 May
11:16 a.m.
On May 27, 2014, at 1:15 PM, Henk <henk.gooijen at hotmail.com> wrote:
-----Oorspronkelijk bericht----- From: Tony Duell
Sent: Tuesday, May 27, 2014 8:08 PM
To: cctalk at classiccmp.org
Subject: Re: Catch and Halt Fire - Drama set in early days of personal computing
Actually, the HP 2114/2115/2116 series of minicomputers could get into an
"infinite indirect loop" that could be really fun to break out of. No
undocumented
features.
If an instruction did an indirect memory reference and the referenced
memory location had bit 15 set (which indicated further redirection) the
instruction won't complete until it fetches a word with bit 15 clear. A bug
where a word refers to itself (with bit 15 set) or back further in the chain
would result in an "infinite indirect loop". This was unbreakable since
interrupts are only processed at the completion of an instruction. A reset
was the only way to break out of it.
TTFN - Guy
Halt and Catch Fire is not a real computer
instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
I thought there was at least one microprocessor (Motorola 6800?) where an
undocumented instruction would cause the processor to simply do memory
cycles at the fasted posible rate, address incrementing each time, and
the procesosr ignored all inputs apart from reset.
While the machine did not catch fire, the system was essentailly locked
up until the hardware reset.
-tony
As usual, Tony is correct.
I remember that the 6800 has an undocumented (illegal) opcode
that did cycle through all addresses at clock speed. IIRC, it was also
mentioned in a BYTE article (when BYTE was still a joy to read).
12:32 p.m.
On 05/28/2014 08:16 AM, Guy Sotomayor wrote:
If an instruction did an indirect memory reference and
the referenced
memory location had bit 15 set (which indicated further redirection) the
instruction won't complete until it fetches a word with bit 15 clear. A bug
where a word refers to itself (with bit 15 set) or back further in the chain
would result in an "infinite indirect loop". This was unbreakable since
interrupts are only processed at the completion of an instruction. A reset
was the only way to break out of it.
If memory serves, there were more than one or two old systems where
infinitely looped indirect addressing was possible.
Were there any where looped "Execute" instructions were possible?
--Chuck
3:50 p.m.
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 6:32 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Catch and Halt Fire - Drama set in early days of personal
computing
On 05/28/2014 08:16 AM, Guy Sotomayor wrote:
If an instruction did an indirect memory reference and
the referenced
memory location had bit 15 set (which indicated further redirection) the
instruction won't complete until it fetches a word with bit 15 clear. A
bug
where a word refers to itself (with bit 15 set) or back further in the
chain
would result in an "infinite indirect loop". This was unbreakable since
interrupts are only processed at the completion of an instruction. A
reset
was the only way to break out of it.
If memory serves, there were more than one or two old systems where
infinitely looped indirect addressing was possible.
Were there any where looped "Execute" instructions were possible?
--Chuck
Long ago, I worked on SPERRY 1100 systems (1100/63 and 1100/72), and
was one of the very few people allowed to program MASM. Makes sense,
as I was one of the two EXEC experts (I could read the panic dump and
find out why the system crashed). As said, long ago ...
I remember the EX (execute remote) instruction. I wonder what would
happen if you EX to another EX instruction that EX'd the first EX. That
would cause a loop, I guess. But both systems that I worked on, the
system would not hang, just the CPU executing the EX code.
I also remember a dumb code error ... that caused the system to hang.
The only solution was "$!" from the system console (causes a boot!).
It was a production machine, so my boss was not too glad. My program
executed ER DED$ (IIRC), which permanently allocates a CPU to the
program. The mistake was that the ER (Execute Request) was in a loop ...
Ahh, fond memories still :-)
- Henk
4:42 p.m.
On 05/28/2014 12:50 PM, Henk wrote:
Long ago, I worked on SPERRY 1100 systems (1100/63 and
1100/72), and
was one of the very few people allowed to program MASM. Makes sense,
as I was one of the two EXEC experts (I could read the panic dump and
find out why the system crashed). As said, long ago ...
I remember the EX (execute remote) instruction. I wonder what would
happen if you EX to another EX instruction that EX'd the first EX. That
would cause a loop, I guess. But both systems that I worked on, the
system would not hang, just the CPU executing the EX code.
I seem to recall that the S/360 had a special exception code for an EX
instruction being the object of another EX instruction.
--Chuck
29 May
29 May
4:12 a.m.
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 10:42 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Catch and Halt Fire - Drama set in early days of personal
computing
On 05/28/2014 12:50 PM, Henk wrote:
Long ago, I worked on SPERRY 1100 systems (1100/63 and
1100/72), and
was one of the very few people allowed to program MASM. Makes sense,
as I was one of the two EXEC experts (I could read the panic dump and
find out why the system crashed). As said, long ago ...
I remember the EX (execute remote) instruction. I wonder what would
happen if you EX to another EX instruction that EX'd the first EX. That
would cause a loop, I guess. But both systems that I worked on, the
system would not hang, just the CPU executing the EX code.
I seem to recall that the S/360 had a special exception code for an EX
instruction being the object of another EX instruction.
--Chuck
I have no access to SPERRY documentation, but I would expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
- Henk
11:02 a.m.
On 05/29/2014 01:12 AM, Henk wrote:
I have no access to SPERRY documentation, but I would
expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
I confess I remember almost nothing about the short time I spent with an
1108. My memory mostly extends to the hardware manuals printed on a
really terrible drum printer. Gave me headaches to read.
--Chuck
2:15 p.m.
From: Henk
Sent: Thursday, May 29, 2014 1:13 AM
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 10:42 PM
> On 05/28/2014 12:50 PM, Henk wrote:
> I remember the EX (execute remote) instruction. I
wonder what would
> happen if you EX to another EX instruction that EX'd the first EX. That
> would cause a loop, I guess. But both systems that I worked on, the
> system would not hang, just the CPU executing the EX code.
I seem to recall that the S/360 had a special
exception code for an EX
instruction being the object of another EX instruction.
I have no access to SPERRY documentation, but I would
expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
On the other hand, the PDP-10 architecture explicitly allows an XCT as the
argument of an XCT, so the looping scenario is possible. However, the
interrupt system should allow the system to break out on a time-slice
expiration, so only the individual process should hang.
Rich
Rich Alderson
Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
2:36 p.m.
I remember discussing Honeywell L66 and later performance with an
ex-Honeywell guy, who I think was called Vince Martin, and lived in
Scottsdale , Arizona. He ran a performance tuning consultancy...
He had some code that worked out how many MIPS the machine could
actually do an any point in time. He said that as the I/O had priority
on the memory access, and there wasn't enough memory bandwidth for
everything to work flat out, the available MIPS could vary between "0"
and the rated MIPS of the machine, depending on load. Whats more the
system monitor display (I can't remember what it was called) measured
CPU Busy not MIPS so the system could show 100% CPU Busy and yet be
doing no MIPS what so ever.
He said, but we never tried it, that if you wrote a looping tape i/o you
could kill the entire machine dead as the 6250 BPI drives we had could
totally max the memory bandwidth leaving no way for the CPU to read data....
So an I/O based "halt and catch fire" perhaps...
Dave
G4UGM
On 29/05/2014 19:15, Rich Alderson wrote:
From: Henk
Sent: Thursday, May 29, 2014 1:13 AM
--
Dave Wade G4UGM
Illegitimi Non Carborundum
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 10:42 PM
On the other hand, the PDP-10 architecture explicitly allows an XCT as the
argument of an XCT, so the looping scenario is possible. However, the
interrupt system should allow the system to break out on a time-slice
expiration, so only the individual process should hang.
Rich
Rich Alderson
Sr. Systems Engineer
Living Computer Museum
2245 1st Avenue S
Seattle, WA 98134
mailto:RichA at LivingComputerMuseum.org
http://www.LivingComputerMuseum.org/
On 05/28/2014 12:50 PM, Henk wrote:
I remember the EX (execute remote) instruction. I wonder what would
happen if you EX to another EX instruction that EX'd the first EX. That
would cause a loop, I guess. But both systems that I worked on, the
system would not hang, just the CPU executing the EX code.
I seem to recall that
the S/360 had a special exception code for an EX
instruction being the object of another EX instruction.
I have no access to SPERRY documentation, but I would expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
5:36 p.m.
On 5/29/2014 11:15 AM, Rich Alderson wrote:
From: Henk
Sent: Thursday, May 29, 2014 1:13 AM
SIMH seems to limit XCT nesting to 32. It also limits indirect effective
address nesting to 32.
I don't seen any limitation for this kind of nesting in the KS10
microcode and the indirect effective addressing doesn't look to be
interruptable.
Rob.
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 10:42 PM
> On 05/28/2014 12:50 PM, Henk wrote:
> I remember the EX (execute remote)
instruction. I wonder what would
> happen if you EX to another EX instruction that EX'd the first EX. That
> would cause a loop, I guess. But both systems that I worked on, the
> system would not hang, just the CPU executing the EX code.
I seem to recall that the S/360 had a special
exception code for an EX
instruction being the object of another EX instruction.
I have no access to SPERRY documentation, but I
would expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
On the other hand, the PDP-10 architecture explicitly allows an XCT as the
argument of an XCT, so the looping scenario is possible. However, the
interrupt system should allow the system to break out on a time-slice
expiration, so only the individual process should hang.
6:51 p.m.
On 05/29/2014 02:36 PM, Rob Doyle wrote:
On 5/29/2014 11:15 AM, Rich Alderson wrote:
The CDC-3300 had more than one rule regarding indirect interruptabilty.
At Oregon State, we had one that had seen considerable work to be
'modified' to match the specifications. :-) It had two rules regarding
following indirect chains. Every word had an indirect bit and if set,
would forward the indirection to the next word. In "monitor" state
(supervisor) indirect chains were not interruptable. In 'program' state
they were.
This led to some juggling in our operating system (OS-3) which would
'simulate' an indirect chain when recovering from a page fault
interrupt. Since we couldn't guarantee that all of memory was resident
in order to follow some ridiculously long chain, the OS would do it
page-at-a-time if necessary so that the entire indirect chain wouldn't
need to be restarted from scratch in order to restart the user. On a
system with only 48 pages of real memory (96k words) having 16
instantiated pages (32k) at once was rare when running 50+ users :-)
The fact this worked correctly may have been a fluke at our site. I do
know CDC spent some considerable effort getting floating point and other
functional pieces working in a manner that allowed 'restartable'
instructions. The BDP (business data processor) we a real bear. It had
very complex decimal and character handling instructions (used only by
COBOL, thank dog.) It even possessed hardware instructions akin to an
'sprintf'!
Under Master (CDC's 'timesharing' OS) an interrupt from the user for any
reason other than peripheral or timer was considered an ABORT so they
didn't worry about restartability as far as I could tell.
-Gary
From: Henk
Sent: Thursday, May 29, 2014 1:13 AM
SIMH seems to limit XCT nesting to 32. It also limits indirect effective
address nesting to 32.
I don't seen any limitation for this kind of nesting in the KS10
microcode and the indirect effective addressing doesn't look to be
interruptable.
Rob.
-----Oorspronkelijk bericht-----
From: Chuck Guzis
Sent: Wednesday, May 28, 2014 10:42 PM
> On 05/28/2014 12:50 PM, Henk wrote:
> I remember the EX (execute remote)
instruction. I wonder what would
> happen if you EX to another EX instruction that EX'd the first EX.
> That
> would cause a loop, I guess. But both systems that I worked on, the
> system would not hang, just the CPU executing the EX code.
I seem to recall that the S/360 had a special
exception code for an EX
instruction being the object of another EX instruction.
I have no access to SPERRY documentation, but I
would expect
that the 1100 also would recognize EX targeting an other EX and
generate an exception or trap. IIRC the word is 'contingency' in the
1100 jargon for 'exception'. End 80's memory cells starts to fail ...
On the other hand, the PDP-10 architecture explicitly allows an XCT
as the
argument of an XCT, so the looping scenario is possible. However, the
interrupt system should allow the system to break out on a time-slice
expiration, so only the individual process should hang.
28 May
28 May
4:09 p.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
Actually, the HP 2114/2115/2116 series of
minicomputers could get into an
"infinite indirect loop" that could be really fun to break out of. No
undocumented
features.
If an instruction did an indirect memory reference and the referenced
memory location had bit 15 set (which indicated further redirection) the
instruction won't complete until it fetches a word with bit 15 clear. A bug
where a word refers to itself (with bit 15 set) or back further in the chain
would result in an "infinite indirect loop". This was unbreakable since
interrupts are only processed at the completion of an instruction. A reset
was the only way to break out of it.
THis also applies to the processor used in the HP9810/9820/9830 desktop
'calculaotrs'. It's a related instruction set IIRC, and the indirection
can indeed get into an endless loop. This is handled by the CPU
microcode, and since that's also responsible to checkign interrupts at
the stnart of every instruciton, an interrupt will not get out of it. The
only thing that will is a hardware reset.
For interest, here's the appropraite bit of the CPU microcode (addresses
in split octal, data in hex) :
--
Memory Reference -- calculate address
0012 : 5ef398b : TTM=0;TTT=1;SC=2(TTS);X=7(NOP);R=7(ZTR);ALU=2(IOR);BRC=1
0012 : 5ef398b : IQN=0;XTR=1;clk=9;sec=1;pri=b;
0012 : 5ef398b : M = (T) IOR (0);
0012 : 5ef398b : clocks=10; if (Q10/) goto (1313,1312)
Copy lower 10 bits of instruction (in T) -- address part of the
instuction -- to the M register. The high bits of M, giving the current
page, end up in the LSBs of M. Test bit 10 of the instruction to
determine if it's base page or current page.
1312 : 4e77542 : TTM=0;TTT=1;SC=0(ZTS);X=7(NOP);R=7(ZTR);ALU=3(ZTT);BRC=0
1312 : 4e77542 : IQN=0;XTR=1;clk=5;sec=8;pri=2;
1312 : 4e77542 : M = (0) ZTT (0);
1312 : 4e77542 : clocks=6; goto (1102)
Base page : Shift 6 0's into M, thus forming a base page address
1313 : ee775c2 : TTM=1;TTT=1;SC=1(MTS);X=7(NOP);R=7(ZTR);ALU=3(ZTT);BRC=0
1313 : ee775c2 : IQN=0;XTR=1;clk=5;sec=9;pri=2;
1313 : ee775c2 : = (M) ZTT (0);
1313 : ee775c2 : clocks=6; goto (1102)
Current page : Rotate M by 6 bits, so original 6 MSBs end up in the MSBs
of M (thus keeping the current page)
1102 : cfb1b89 : TTM=1;TTT=1;SC=0(ZTS);X=7(NOP);R=6(RDM);ALU=4(ZTTCBC);BRC=1
1102 : cfb1b89 : IQN=0;XTR=1;clk=b;sec=1;pri=9;
1102 : cfb1b89 : = (0) ZTTCBC (); RDM ;
1102 : cfb1b89 : clocks=12; if (Q15/) goto (0003,0002)
Read in the addressed memory word. Check bit 15 of the instruction (in Q)
to determine if it's indirect or not. Clear BC (needed by PC increment
routine, amongst others)
0003 : 5e13f86 : TTM=0;TTT=1;SC=2(TTS);X=7(NOP);R=4(TQ6);ALU=2(IOR);BRC=0
0003 : 5e13f86 : IQN=0;XTR=1;clk=f;sec=1;pri=6;
0003 : 5e13f86 : M,Q6 = (T) IOR ();
0003 : 5e13f86 : clocks=16; goto (0602)
It is indirect. Copy read-in memory word (indirect address) into M. Shift
bits into Q(6) also, so that Q(6) ends up set to the state of the MSB of
this address. This is set if this address is also indirect
0602 : ceb7b86 : TTM=1;TTT=1;SC=0(ZTS);X=7(NOP);R=6(RDM);ALU=3(ZTT);BRC=1
0602 : ceb7b86 : IQN=0;XTR=1;clk=b;sec=1;pri=6;
0602 : ceb7b86 : = (0) ZTT (); RDM ;
0602 : ceb7b86 : clocks=12; if (Q6/) goto (0003,0002)
Read in data word. Test to see if this needs to be indirected again. If
so, go back and do so
At this point, M contains the address specified in the instruction
(indirected if necessary), T contains the contents of that address.
--
Basiclly, you can get stuck in the 2 microstae loop 0003, 0602 if the
indirect address pointso t oa word with the MSB set each time.
Of coruse the 9810/20/30 were not officially programmable in machine
code. But...
-tony
27 May
27 May
4:26 p.m.
Here's a copy of the fake op-codes from my archives, 1984:
http://www.textfiles.com/humor/COMPUTER/opcodes.hum
http://www.textfiles.com/humor/COMPUTER/commands.hum (1985)
http://www.textfiles.com/humor/COMPUTER/opcodes1.jok (Claims 1969/70!)
On Tue, May 27, 2014 at 2:08 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Halt and Catch
Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
I thought there was at least one microprocessor (Motorola 6800?) where an
undocumented instruction would cause the processor to simply do memory
cycles at the fasted posible rate, address incrementing each time, and
the procesosr ignored all inputs apart from reset.
While the machine did not catch fire, the system was essentailly locked
up until the hardware reset.
-tony
6:44 p.m.
IIRC, later Commodore 64 computers could lock up and eventually damage the 6502 if they
executed a certain invalid opcode -- something tells me it was 0x05, but I can't swear
to it.
On May 27, 2014, at 1:08 PM, "Tony Duell" <ard at p850ug1.demon.co.uk>
wrote:
Halt and Catch
Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
I thought there was at least one microprocessor (Motorola 6800?) where an
undocumented instruction would cause the processor to simply do memory
cycles at the fasted posible rate, address incrementing each time, and
the procesosr ignored all inputs apart from reset.
While the machine did not catch fire, the system was essentailly locked
up until the hardware reset.
-tony 
2 Jun
2 Jun
1:20 p.m.
>> Halt and Catch Fire is not a real computer
instruction that caused
>> a race condition that made the computer stop working.
Not a race condition, no. But the Jargon File entry for HCF says
Mnemonic for `Halt and Catch Fire', any of several undocumented and
semi-mythical machine instructions with destructive side-effects,
supposedly included for test purposes on several well-known
architectures going as far back as the IBM 360. The MC6800
microprocessor was the first for which an HCF opcode became widely
known. This instruction caused the processor to toggle a subset of the
bus lines as rapidly as it could; in some configurations this could
actually cause lines to burn up. Compare killer poke.
The referenced entry ("killer poke") says
A recipe for inducing hardware damage on a machine via insertion of
invalid values (see poke) into a memory-mapped control register; used
esp. of various fairly well-known tricks on bitty boxes without
hardware memory management (such as the IBM PC and Commodore PET) that
can overload and trash analog electronics in the monitor. See also
HCF.
It seems obvious to me that this/these is/are what the subject show is
alluding to, mangled as usual by writers who don't actually understand
what they're writing about.
/~\ The ASCII Mouse
\ / Ribbon Campaign
X Against HTML mouse at rodents-montreal.org
/ \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
29 May
29 May
4:59 a.m.
Character-view: http://www.c2meworld.com/flink/halt-and-catch-fire/
On Tue, May 27, 2014 at 2:08 PM, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
Halt and Catch
Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
I thought there was at least one microprocessor (Motorola 6800?) where an
undocumented instruction would cause the processor to simply do memory
cycles at the fasted posible rate, address incrementing each time, and
the procesosr ignored all inputs apart from reset.
While the machine did not catch fire, the system was essentailly locked
up until the hardware reset.
-tony
28 May
28 May
10:30 a.m.
On Mon, May 26, 2014 at 1:35 PM, Sellam ibn Abraham
<sellam at vintagetech.com>wrote:
I watched about 3 minutes. Pure garbage.
Halt and Catch Fire is not a real computer instruction that caused a race
condition that made the computer stop working. I imagine a bunch of
teenagers are scouring Intel technical manuals looking for the Code 2 Duo
equivalent of HCF.
No one looked, acted, or talked like that back in the early 1980s (I
remember, I was there). Especially not IBM sales people.
If you could find a chick anywhere that looked 1/4 as cute as the chick in
the opening scene and who knew as much about computers, you were either in
the future, watching a bad 2014 television drama, or you were someplace
private by yourself with your pants down lost in your imagination.
I'm sure I could come up with more criticisms if I could deaden my senses
enough without taking out critical life functions to watch the rest.
Unfortunately, this program was designed for the braindead, technically
illiterate cultural group that comprises television watchers generally.
Next thing you're gonna tell me is that travel through time and space is
preposterous and there's no blue box that can do it.
3:56 p.m.
New subject: Catch and Halt Fire - Drama set in early days of personal
Next thing you're gonna tell me is that travel
through time and space is
preposterous and there's no blue box that can do it.
I've never had any problems travelling forwards in time. Just sit down
and wait...
-tony
3702
days inactive
3710
days old
40 comments
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