A FAIR DEBATE

[ka9q]

So, a sort of saturable reactor/mag amp setup. That is clever...the descriptions I found weren't very detailed, and left the impression that each word had its own address line with an external multiplexer.

There's actually more than one way to make a read-only transformer memory (as I think it's called) and several distinct designs can be found in the Apollo literature. That confused a bunch of us as to which was actually used in the AGC.

I think all were used in various places; e.g., IBM used a different architecture to contain the software for a peripheral controller.

As you point out, the arrangement of the Apollo core rope memory minimized the number of components, and that's highly desirable in hardware designed for space. But this came at significantly increased manufacturing complexity; consider what was required to change a single bit in the memory to correct a software bug. You'd have to unthread an entire sense wire and rethread another one, making the change in just one of the cores it has to traverse. The IBM scheme had a clever book-like structure with pages that were essentially very thin circuit boards that could be individually replaced to change a given word of memory.

[cjameshuff]

As you point out, the arrangement of the Apollo core rope memory minimized the number of components, and that's highly desirable in hardware designed for space. But this came at significantly increased manufacturing complexity; consider what was required to change a single bit in the memory to correct a software bug. You'd have to unthread an entire sense wire and rethread another one, making the change in just one of the cores it has to traverse. The IBM scheme had a clever book-like structure with pages that were essentially very thin circuit boards that could be individually replaced to change a given word of memory.

I'm reminded of a IC ROM technology that was already available at the time...you could get custom ROM ICs, written by physically scratching out individual bits on the die. Only worthwhile for small quantities...a mask ROM would be used for mass production. Much easier to work with than core rope, though, once you had the chips in production.

And rewritable magnetic core memory and similar technologies like plated wire and thin film memory continued to get denser and cheaper, and one-time programmable PROMs and UV-erasable EPROMs became commercially available shortly after the first moon landing...core rope didn't stick around long.

[bobdude11]

WOW! I feel like an elementary school kid compared to you folks - I have been interested in computers for a long time, but I never experienced any of the older style (having been brought up on modern 'digital' computers (the TRS-80 Model 1, Level 1 being the first). I am going to really have to watch and read to fully understand everything.

Thank you all SO much for the help - I can't wait to learn something new!!!

[ka9q]

I'm reminded of a IC ROM technology that was already available at the time...you could get custom ROM ICs, written by physically scratching out individual bits on the die.

Are you thinking of fusible link PROM, or is this something else I haven't heard of? I was using fusible link PROMs until the late 1970s when UV erasable PROMs took over.

I do know that in the mid 90s Intel developed the ability to program individual chips with unique values with a laser. They used this to implement the infamous Pentium III serial number that triggered so much opposition that they withdrew the feature. (Not that it matters much; modern computers have plenty of unique system-identifying information, starting with network interface addresses.)

And rewritable magnetic core memory and similar technologies like plated wire and thin film memory continued to get denser and cheaper

Yes. I'm not as familiar with the IBM-developed Launch Vehicle Digital Computer used in the Saturn Instrument Unit, but I get the impression that the program was stored in read/write core. Is that so? It certainly would have made software updates a lot easier than in the AGC, but at the expense of a lower density. Maybe the Saturn was easier to fly than the CSM or LM.
 

[cjameshuff]

Are you thinking of fusible link PROM, or is this something else I haven't heard of? I was using fusible link PROMs until the late 1970s when UV erasable PROMs took over.

No, a Sylvania system where technicians went at the die under a microscope and physically scratched out metal traces exposed for that purpose. (There were only 256 bits to worry about...think of a 32x8 array.)

There's not much on it out there...it was probably pretty much immediately superseded by PROMs.

Yes. I'm not as familiar with the IBM-developed Launch Vehicle Digital Computer used in the Saturn Instrument Unit, but I get the impression that the program was stored in read/write core. Is that so? It certainly would have made software updates a lot easier than in the AGC, but at the expense of a lower density. Maybe the Saturn was easier to fly than the CSM or LM.

Don't know. The AGC is the only system I know of that used core rope memory. The Mariner probes may have as well, but I haven't been able to find specific details. I've found references to a Mars lander that never got off the ground that used it...I think the Viking landers used plated wire memory for all their needs.

Normal core memory was more amenable to increases in density than core rope. It requires a core per bit rather than a core per word, but the cores can be much smaller and packed closer together. I wouldn't be surprised if it exceeded core rope in density before being replaced by things like plated wire memory.

[ineluki]

That's how I figure reputable actors end up in disreputable movies, too.  We refer to them around here as "grandmother in a basement" movies--someone's got the person's grandmother at gunpoint in a basement somewhere unless whoever-it-is agrees to make a terrible movie.

Sounds more exciting than the probable truth of "Money, Dear Boy".

[gillianren]

Sometimes, "money, dear boy" doesn't seem to go anywhere near far enough.

[Echnaton]

I have attributed it, at least in part, to the fact that you can't always tell how a movie will turn out when you sign the contract.  A good partial script can turn in to an awful completed script or the budding young director can turn out to be a hack when given full control of a major film.  Even seasoned directors turn out duds.  It is part of the result of reaching for artistic goals amid the need keep within a budget and reach a broad enough audience.

[gillianren]

But why do skilled actors keep appearing in Uwe Boll films?

[Tedward]

Sure I heard Michael Cain on one of them TV chat shows and asked why he appeared in a bad film, he said it paid for his mothers new house with a grin. Not the house with a grin Mr Cain said with a grin.

From memory so it might have been Michael York talking about another film...... nah, pretty sure it was that.

[Al Johnston]

There was a great line in an episode of Not the Nine O'Clock News:

"Sir John Geilgud has defended his appearance in the film Caligula, saying there was no mention of sex and violence when he read the original paycheque."

[ineluki]

Sure I heard Michael Cain on one of them TV chat shows and asked why he appeared in a bad film, he said it paid for his mothers new house with a grin. Not the house with a grin Mr Cain said with a grin.

Probably Michael Caine about Jaws: The Revenge:
"I have never seen the film, but by all accounts it was terrible. However I have seen the house that it built, and it is terrific."

[Tedward]

Bit of thinking, it involved bees. Looks like the Swarm, mind you, never seen that Jaws one, maybe it paid for the garage....

[gillianren]

I can't think appearing in Uwe Boll films pays for much.  And you have to work with Uwe Boll, which makes it not worth it no matter how much it pays.

[Tedward]

Had to google him. I just assumed he was a director of no fame yet. I see what you mean. I suppose you cannot fathom every actor.