Halt and Catch Fire


Boy, I really do look like Mary Stuart Masterson

Is this show something more than a tense relationship between a meterosexual narcissist with vision, a brooding middle aged hardware designer with struggling between his need for self-fulfillment and familial responsibilities, and a young genius who is obviously the love child of Meg Ryan and Mary Stuart Masterson?

I couldn’t help but be drawn in right away by Joe’s Porsche 944. My wife says that any Porsche is an indication that a guy is a real ass, but I’ve always dreamed of owning a 944 someday anyway. Maybe I’m just an ass.

So, what’s good about Halt and Catch Fire?

1. Gordon Clark – his character is awesome. He’s talented but scarred. There’s a history of a previous computer project that had serious consequences for him and his family. He’s dying to break out and create something, but he can’t escape his fears. The struggle with his wife is realistic and compelling and I am identifying most with this storyline – not because I have Gordon’s talent, but I do struggle with the competing forces of my desire to make something and my need to stay within the lines.

(From my old home, West Philadelphia)

2. Donna Clark – Gordon’s wife and not just a weak supporting character. She’s talented in her own right and provides a great foil against Gordon’s ambitions, because she understands them. It would be easy to pair Gordon with a home-maker wife or someone who works outside the home, but in an entirely different industry or capacity. Instead, she’s an insider who worked with Gordon in the past on their previous project and previews tell us that she has a future in this project as well.Image

3. Despite the fact the Joe clearly is Steve Jobs, episode 1 made it clear right from the start that he is not Steve Jobs, but someone with very similar talents for getting people together and pushing them beyond their boundaries. But Gordon nails him right away for stealing one of Jobs’ most iconic lines about ‘putting a dent in the universe.’ This is another case of it being easy for the show to just recast Jobs in their show, steal his lines and make believe like it’s all original. Instead, we see that Joe is like jobs, but is also true to Picasso’s quote, ‘Good artists borrow; great one’s steal.’ Joe is clearly willing to beg, borrow and steal to get what he wants (-oh, and sleep with anyone).

4. not talking down to us as an audience (although, I will say just the opposite below)

What am I having problems with?

1. The legal framework behind the protagonists’ hacking an IBM computer. Although I get how this brings up obvious issues of copyright, etc. I would have liked a little more clarity on how what they did was infringing Patent long before they ever moved to actually make a computer. I also would have liked a little more clarity on how their retroactive legitimization cleared them. This second part is a lot more obvious, and I’m OK with how it was treated so long as the first part is simplified (just slightly).

2. Cameron’s character is still too one-dimensional. I expect to see her flesh out over time, but so far, she’s not added much to the show other than a stereotype.

3. Joe. Like Cameron, his character needs time to unfold, and I expect him to do just that. He’s obviously tortured, a liar and manipulative (all traits that should get his character on the first list above), but he is also too tortured, a liar and manipulative. Like Cameron, he’s still one-dimensional.

Overall, I have high hopes for this series. Too bad it’s yet another that my wife won’t be watching with me.




“Undocumented M6800 Instructions”
by Gerry Wheeler,
Computer Communications Network Group
University of Waterloo
Waterloo, Ontario, Canada
December 1977 BYTE, Volume 2, Number 12, pages 46-47.

According to Motorola, there are 197 valid operation codes for the
M6800 microprocessor.  This means that, of the 256 possible 8-bit
combinations, 59 are called invalid instructions.


Let me tell you about a couple of the interesting ones.  See table 1
for descriptions of six instructions that Motorola didn’t tell us
about.  The mnemonics are, of course, assigned by me.


Now for the big surprise.  This one has been dubbed HCF for “Halt and
Catch Fire”.  Well, almost.

When this instruction is run, the only way to see what it is doing is
with an oscilloscope.  From the user’s point of view, the machine
halts and defies most attempts to get it restarted.  Those persons
with indicator lamps on the address bus will see that the processor
begins to read all of memory, sequentially, very quickly.  In effect,
the address bus turns into a 16-bit counter.  However, the processor
takes no notice of what it is reading….it just reads.  The only way
out of this race is with the RESET line.  The machine ignores the
IRQ, NMI, and HALT lines.  For all intents and purposes, the processor
has halted and caught fire!

It is quite possible that the HCF instructions are put into the 6800
design intentionally in the interest of production testing of newly
fabricated processor chips.  This one instruction might provide the
automatic test equipment with a quick initial indication of whether
the particular processor chip is a total dud, or a prospect for more
detailed automatic testing and verification of defect-free operation.


Table 1: A list of six undocumented M6800 instructions and their
definitions.  The operations and operation codes which invoke them
are defined in the column labelled “Result”, and the next instruction
address is given in each case.  Halt and Catch Fire (HCF) does not
have a “next instruction” address, because the processor hangs up.

Hexadecimal                    Next
Name                Mnemonic  Op Code   Result               Instruction At
——————  ——–  ——-   ——————-  ————–

AND accumulators      NBA     14        A.B->A               PC+1

store ACCA, immed     STAA    87        A->PC+2              PC+3

store ACCB, immed     STAB    C7        B->PC+2              PC+3

store SP, immediate   STS     8F        SPh->PC+2;SPl->PC+3  PC+4

store IX, immediate   STX     CF        IXh->PC+2;IXl->PC+3  PC+4

Halt and Catch Fire   HCF     9D,DD     see text             N/A


Since it has now been more than 20 years, I admit that it may possibly
have been this article from which I learned of the HCF instruction in
the 6800, rather than by reading the documentation lying around the
office of BYTE’s Editor-in-Chief Carl Helmers.  Nevertheless, it is a
fact that Carl designed and built his own 6800-based home computer, which
he used for synthesizing electronic music.

That December 1977 issue of BYTE was graced by a Robert Tinney cover
illustration which depicted a hypothetical visit by Captain Kirk, Mr.
Spock, and other USS Enterprise crewmembers to the Spaceport Gamma 6
Holographic Museum of Ancient Technology; they are shown inspecting
an exhibit of a circa-1977 programmer hunched over a DEC LA36 hardcopy
terminal, studying a book entitled, “Understanding BASIC”.

Robert Tinney’s artistry has become integral to the cultural heritage of
the computer industry. Some of his other works may be sampled on the Web:



5 comments on “Halt and Catch Fire

  1. Reblogged this on A Year of Coding and commented:

    Undocumented Code: HCF

  2. I’ve been iffy about Cameron’s character, as well. Gordon hits it out of the park, and I’m hoping Joe will come around. I think Cameron is better than “awful,” but I still haven’t connected with her yet.

    • I’m glad someone else is watching this with me. I really have my fingers crossed for the future of this show. I worried that if I like it too much, that means no one else will and it won’t make it out of the first season.

  3. Tamarah, are you referring to Joe’s willingness to do whatever it takes to make things work the way he wants? (of course, we’ve seen this all along – including his first encounter with Cameron in episode 1)

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