Talk:Computer

US bias in table

The use of red and green colours in table "Defining characteristics of five early digital computers" seems to be intended to suggest that the American ENIAC was the first "real" computer, which it was not.

Zipdude (talk) 08:19, 19 May 2008 (UTC)

under operating systems. It had significant impact on the development of NT, it is still widely used today, has design features (logicals) found in few other systems, and has been supported across a number of platforms, including DEC Alphas, HP Integrity, a couple of Sun devices, as well as x86. —Preceding unsigned comment added by 69.126.40.68 (talk) 16:29, 23 February 2008 (UTC)

Shannon's involvement

The statement "largely invented by Claude Shannon in 1937" (in reference to digital electronics) is inaccurate and should be changed to something more like "enabled by the theoretical framework set forth by Claude Shannon in 1937" 67.177.184.127 (talk) 09:29, 19 February 2008 (UTC)

Heron

Shouldn't Heron's mechanical play be mentioned in the history section. Was it not one of the first programmable devices?

Per my understanding, the device to which you refer, while extremely remarkable, was not programmable. -- mattb @ 2007-04-12T16:25Z

Well my understanding is certainly limited. I saw it on the history channel some months ago. I suppose the 'programming' was rather built into the device and not really modifiable.

The trouble with Heron's mechanical theatre is that we just don't know enough about it. It's hard to say to what degree it was programmable. Certainly it wouldn't count as a "computer" because it didn't manipulate data - but perhaps there is a reasonable claim to be the first programmable machine. I wish there were some really clear explanations of how it worked - but I haven't seen any. I'll have a bash at improving the history section with this information. SteveBaker (talk) 02:10, 16 January 2008 (UTC)

Yesterday I wrote a section on computer components, which got reverted, then rereverted and then reverted again. I know that it didn't add much info, but it did add another perspective. At the moment, the article focuses almost entirely on the logical side of a computer, an important aspect, but it doesn't explain what you see when you open a computer case. Such down to earth information should also be present. At the moment, there is not even a link to the computer hardware article. This is (or should be) an umbrella article, serving different readers, giving an overview of all computer-related aspects and pointing to other articles. I suppose the biggest problem (as usual) is that it is written by experts, which is good, but also usually means the style is rather inaccessible to most encyclopedia readers (this is not a tech corner). Specialised info can go into specialised articles, but this one should also give a grassroots explanation.

As an illustration of what I mean, I wascheese cheeese cheese cheese it myself. It should not necessarily be here, but it should be somewhere and then there should be a link to it in this article (preferably accompanied by a very short overview - the Wikipedia way) because this will be a first stop for people looking for such info.

As for the structure, I worked from the inside out, explaining that the mb connects everything together and then 'hook everything up' to that - can it be part of the mb, does it fit directly onto it, is a cable used and is or can it be inside the computer case - all stuff that isn't evident from the article right now. And also, which components are essential (a graphics card is, unless the mb has that functionality) and which aren't (a sound card isn't). Let me put it this way - such info should be in Wikipedia. Where should it go? DirkvdM 09:34, 19 June 2007 (UTC)

I was rereverting because User:Matt Britt is an established contributor and shouldn't have his changes reverted by a bot. As for the merits of one version over the other, I will side with him; Computers extend beyond PCs, and in my opinion, the new section was too list-y. —Disavian (^talk/_contribs) 13:23, 19 June 2007 (UTC)

Alright then, my last question was where it should go, and you say personal computer, which makes a lot of sense, so I'll put it there. And I'll add a link to that article (and computer hardware) in the 'see also' section, because you may know the distinction between the two, but people look something up in an encyclopedia because they don't know much about it. It's in the intro, but somewhat inconspicuously. Maybe there should be a listing of the types of computer in a table next to the intro. Also, you say the list is too 'listy', but that's what it's supposed to be. What's wrong with lists? DirkvdM 07:04, 20 June 2007 (UTC)

About the list-y bit: according to Wikipedia:Embedded list,

“ Most Wikipedia articles should consist of prose, and not just a list of links. Prose allows the presentation of detail and clarification of context, while a list of links does not. Prose flows, like one person speaking to another, and is best suited to articles, because their purpose is to explain. Therefore, lists of links, which are most useful for browsing subject areas, should usually have their own entries: see Wikipedia:Lists (stand-alone lists) for detail. In an article, significant items should be mentioned naturally within the text rather than merely listed. ”

Of course, there are exceptions; ex: Georgia Institute of Technology#Colleges. —Disavian (^talk/_contribs) 01:00, 22 June 2007 (UTC)

Note that the first word is 'most' and that it speaks of entire articles consisting of a list. This was (or rather is, because it's now in the personal computer article) just a list inside an article. And it isn't even a list, it just has some lists in it. The alternative would be to enumerate them after each other (in-line), which is much less clear. That's a personal preference, I suppose (I like things to be as ordered as possible - blame it on my German background :) ), but I certainly won't be the only person who feels like this. I doubt if that text is meant to be applicable here. DirkvdM 10:24, 24 June 2007 (UTC)

Removal of text

I removed this text from the article:

Five Generations of Computers: Over the 20th century, there have been 5 different generations of computers. These include:

1. 1st Gen => 1940-1956: Vacuum Tubes
2. 2nd Gen => 1956 – 1963: Transistors
3. 3rd Gen => 1964 – 1971: Integrated Circuits
4. 4th Gen => 1971 – Present: Microprocessors
5. 5th Gen => Present & Beyond: AI

Because it appears to be original research. If someone has a source, there shouldn't be much of a problem with re-adding it, so long as it is communicated who proposed this model. Gracenotes^T § 18:39, 16 July 2007 (UTC)

I've just re-removed this text. I agree on the OR claim, but also disagree to an extent with the classification: especially with the "Present and Beyond: AI". Firstly, this is casting speculation on what will drive the industry in the future and secondly 'AI' has been 'the next big thing' since the 1960's. Angus Lepper^{(T, C, D)} 21:19, 16 July 2007 (UTC)

I concur with Gracenotes and Angus Lepper that the text is original research, speculation, and factually incorrect, all of which violate numerous Wikipedia policies and guidelines, and should stay out of the article. --Coolcaesar 19:36, 18 July 2007 (UTC)

The list is correct for the first four generations and is discussed in History of computing hardware, with more detail on the third and fourth generations in History of computing hardware (1960s-present). However there is to date no consensus as to what the fifth generation is (or will be) but for one possibility see Fifth generation computer. --Nibios 04:06, 30 July 2007 (UTC)

how can you tell if after your computer has been 'repaired' if someone has remote access to it

Image Improvement

I believe a better picture of the NASA Super Computer should be shown, as this one is quite an illusion. —The preceding unsigned comment was added by Unknown Interval (talk • contribs) 00:40, August 20, 2007 (UTC). say mucus

In this topic I have to write that this article is not going to be complete without image of, I think today most widely used, simple, PC. I scrolled down the article in hope I will find it, but there isn't. Is it unlogic? For many people around the world, metion of word "computer" at first means PC. But they will not find it here. --Čikić Dragan (talk) 20:27, 13 January 2008 (UTC)

This is an encyclopedia - not a picture gallery. Ask yourself this: What additional meaning could come to the article by showing computers that are essentially the same as the machine the person is sitting in front of as they sit reading Wikipedia. We need to show images that ADD information. Most people think of a computer as a laptop or a desktop PC or something - we can expand on their perceptions by showing images of massive supercomputers, computers made of gearwheels, tiny computers that fit into a wristwatch. To try to keep this article down to some kind of reasonable size, we have to use our available screen space wisely - an photo of a common kind of PC is really largely irrelevant. There would be a case for showing (say) an absolutely original early-model IBM PC - that's of historical value...but a common modern desk-side is just pointless. SteveBaker (talk) 01:52, 16 January 2008 (UTC)

Computer is not an anagram nor acronym for anything.

Please remove this sentence from this article: "The Computer is an anagram standing for 'Commonly Operated Machine Purposefully Used for Technology,Education and Research"

I do not have the established user authority necessary to do it myself.

First of all, whoever entered this claim confused 'anagram' and 'acronym'. Second, an apparently specious claim like this needs to be supported by a citation if it should have any hope of becoming a permanent addition to an article. The modern usage 'computer' has a simple and established etymology (from the word 'compute'). Third, if there is evidence of translating 'computer' as claimed in the sentence, it should be called a backronym and the evidence should be cited.Taajikhan 22:10, 17 September 2007 (UTC)

Thank you for removing that. That was a vandalous edit. · AndonicO ^Talk 23:23, 17 September 2007 (UTC)

The claim was entered yesterday and i did not believe it, how ever i was not entirely sure of the possibility of it being incorrect, i reworded the sentence (yes confusing anagram and acronym) and added {{fact}}.the sentance added was Commonly Operated Machine Purposefully Used for Technology,Education and Research how ever [1] comes up with Common Operating Machine Particularly Used For Trade Education And Research [2] came up with the same thing. I shall reinstate a sentence in the article with these citations.Blacksmith ^talk 05:57, 18 September 2007 (UTC) gah, right heres 2 from yahoo [3][4] however it could be a backronym, it might be worth placing and addressing this in the article to clear it up and prevent further additions of this kind. e.g The word computer has several backronyms, most of which are similar to the following 'Commonly Operated Machine Purposefully Used for Technology,Education and Research'.

Etymology of the word 'Computer', as confirmed by the Oxford American Dictionary on my iMac, is from French computer, which is from Latin computare, to settle or to calculate. 'Computer' was originally a term for a person who computed data, and then carried over to the machines which could do the same thing. --Nucleusboy 23:21, 18 September 2007 (UTC)

The two sources sited at last revision #158664892 are not convincing. Please do not put this claim back into the article without reliable citation and further discussion. Citation should include the original source of the acronym (akin to an etymology). If this claim is verified, it should be put in the History section, as the acronym is not a definition of the word today. Ajonlime 01:58, 19 September 2007 (UTC)

Ajonlime, we currently have four sources on this, i do beileve this is enough to claim it is at least an backronym, Nucleusboy, we have decided it is a backronym, the decision is just to add it into the article even if just to prevent further additions, or possible, 'Computer comes from the latin word compute....,'i think we should add this. do not say we should just leave the wikitionary link at the bottom, for in many other articles we do explain the meanting and origin of the word. Wikipedia should be a oner stop encyclopedia, and visitors shold have to go to as little pages as possible. An article should cover a broad range of subjects within one topic. This article, (not exactly certain whjat the entire content is, i mainly focus on the first section) should have an introduction, containing a brief description of what a computer is, what its is used for, its origin etc, and the following sectilons should expand on this.Blacksmith ^talk 09:22, 19 September 2007 (UTC)

There is simply no way that claim can be true because the word 'computer' was originally used for people who computed. That can't have been an ancronym where 'm' stood for 'machine' - so this is definitely bogus and needs to be deleted. Even calling it a backronym is wrong because back-formed acronyms are formed and then commonly used - this version of the word is NEVER used . SteveBaker 18:58, 19 September 2007 (UTC)

I had no idea this would generate so much discussion when I posted this. Blacksmith, it's commendable that you want to include as much info as possible, but then you get into the core philosophy of what Wikipedia is about. I'm sure that's a whole different and expansive issue. In this case we need to consider what value it adds to the article. At this point I want to say to SteveBaker that I don't think we should apply absolutes here, I'm sure some people like to say that 'computer' stands for some long phrase. I don't think backronyms require common acceptance, as long as a word with a historical etymology rooted in normal words is then used to construct an acronym, it can be considered a backronym. Did that make sense? People also make backronyms for the sake of humor or to demonstrate their prowess with language, even if they never catch on with everyone else.

We need to ask, how crucial is this claim to a person's understanding of what computers are? Besides, where would it appropriately fit in the article, anyway? At best it's a piece of trivia, but trivia sections are discouraged. Maybe the etymology of computer should be put into the history section. Or better yet, both the scholarly and folk etymology (including the backronym definition) might find a better home in the Wiktionary.Taajikhan 22:35, 19 September 2007 (UTC)

It reminds me of the massive, and ever-growing, list of wacky euphemisms for masturbation that used to be farmed at the bottom of that article. (In the end it got moved to wikisaurus.) If we want to include every clever-dick name that some wise-guy ever called their computer at any time, we'd end up with a very long 'Popular culture' section indeed. --Nigelj 09:08, 20 September 2007 (UTC)

I wonder at what point in the evolution of calculating devices did the threshhold reach the level of the title "computer" - as defined by both historical and current definitions? Mechanical ---> electromechanical ---> electronic ... Those ancient IBM punchcard-reading machines that companies once used for processing payroll did much of the same work tht modern computers perform today. And then where do we draw the dividing line that separates "calculator" from "computer" - or any other microprocessor-equipped device that does not nominally wear the "computer" label? —Preceding unsigned comment added by 38.106.99.202 (talk) 09:38, 7 October 2007 (UTC)

DEC Alpha Architecture not listed in 64-bit VLSI table

Any reason for that? See: DEC Alpha - Metrax 09:56, 18 October 2007 (UTC)

computer's future

that's it —Preceding unsigned comment added by 64.62.138.12 (talk) 07:52, 23 October 2007 (UTC)

Homebrew computer

Perhaps the article can add a section about homebrew (or DIY) computers. People as Dennis Kuschel are starting to make a complete computer almost from scratch (by combining electronic components). Also a Dutch guy called Henk van de Kamer is making for example a complete CPU from basic transistors.

People have done this for years; it's almost a homage to the days of discrete component and SSI/MSI IC-based computers. Anyway, this information is more of the trivial sort than of fundamental importance to computers in general. 74.160.109.8 00:04, 6 November 2007 (UTC)

Yes but I believe now, powerful computers (with up to 1200+ CPU's) may be created while the spying of the trusted computer alliance may be avoided. Further searching led me to the OpenCores RISC 1200 CPU ), and the AVR Webserver project (made diy) from Ulrich Radig (see Elektor article) based on the ATMega644 AVR and the Ethernet-based-appliance control (see Ethernet appliances). —Preceding unsigned comment added by 81.246.178.53 (talk) 12:34, 23 November 2007 (UTC)

Update: it seems it is already possbile and available at wiki ! See ECB_AT91 —Preceding unsigned comment added by 81.246.158.33 (talk) 12:57, 23 November 2007 (UTC)

Deletion and redirect of Computer system

The computer system article was recently deleted and redirected to computer. A problem with this is that in many of the articles linking to computer system (see here), the term "computer system" is used to mean a "combination of hardware and software", rather than a "computer". The links in those articles need tidying up if WP is not going to have a "computer system" article. Maybe the instances that mean hardware and software could link to computing instead, if there is not going to be a "computer system" article. Nurg 03:49, 11 November 2007 (UTC)

I realize that I may be horribly late to the party, but I also would promote that these two articles would lead to two entirely different discussions. Mjquin_id (talk) 00:01, 18 July 2008 (UTC)

CPU section

Very good article, but just from the perspective of a beginner reading the article such as myself, it would've been easier to understand if the CPU had been given an overall paragraph of information on how it functions as a whole first, instead of just talking about the ALU and control unit straight away individually. —Preceding unsigned comment added by 60.234.157.64 (talk) 05:33, 11 November 2007 (UTC)

Computer => Latin

Please add Computer is a word of origin of the latin verb (Latin) “computare”, that means "to count" or "to calculate"

It isn't necessary to explain word etymology on an encyclopedia page. Computer is itself a derivative noun from compute, which has the same Latin etymology. - Katavothron (talk) 18:52, 20 November 2007 (UTC)

Input/Output

Inside the Input/Output topic, the author mentions that there are fifty or so computers within a single computer. I considered this highly inaccurate and changed this to something more simplified, but have been reverted with the editor saying it was better written and added the processor and VRAM making it more logical to keep. I don't agree with that decision simply because a computer really is just the processor and memory working together to have an output, and even though there are embedded systems with various configurations and limited programmability, it wouldn't have fifty boards. I'll try to clean up the article a little again, and if reverted once again will try to find a consensus, because this simply doesn't make sense. --Bookinvestor 01:41, 2 December 2007 (UTC)

I concur with Bookinvestor that the sentence is highly inaccurate and should be modified or deleted. Whomever wrote that has either never read a basic textbook on computer architecture (e.g., John L. Hennessy's classic textbook, which I've read twice over the years) or has not completed a freshman course in formal written English at a decent university. --Coolcaesar 05:57, 2 December 2007 (UTC)

The sentence doesn't seem all that misleading to me. GPU's do much parallel processing and have many ALUs operating in parallel. This article, for instance, describes a GPU using 128 processors. Of course this doesn't mean 128 boards - the processors are sections of a single IC chip. -R. S. Shaw 06:49, 2 December 2007 (UTC)

I've read the article and have also found the wikipedia article stream processing. Although I really want to delete the whole paragraph, perhaps I should study a little more into what the author's trying to say because it opens a whole new realm of learning. I'll add this link to the paragraph to see exactly what the author's talking about with GPUs, and hope someone would be able to research with me. Thank you for your contribution Shaw. --Bookinvestor 19:24, 3 December 2007 (UTC)

The informartion provided is really useful

Hi to all !!The material written here is very useful. Thanks. Jack

History

"In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine".[3] Due to limited finances, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine."

1938 built Konrad Zuse the first Z1, the german was faster than americans... Why is in the history nothing about the german technologie? ---Green_Link~~ —Preceding unsigned comment added by 88.66.104.3 (talk) 13:37, 8 January 2008 (UTC)

Oh sorry, the false example. From the german wiki: "1935 stellten IBM die IBM 601 vor, eine Lochkartenmaschine, die eine Multiplikation pro Sekunde durchführen konnte. Es wurden ca. 1500 Exemplare verkauft. 1937 meldete Konrad Zuse zwei Patente an, die bereits alle Elemente der so genannten Von-Neumann-Architektur beschreiben. Im gleichen Jahr baute John Atanasoff zusammen mit dem Doktoranden Clifford Berry einen der ersten Digitalrechner, den Atanasoff-Berry-Computer und Alan Turing publizierte einen Artikel, der die Turing-Maschine, ein abstraktes Modell zur Definition des Algorithmusbegriffs, beschreibt."

In englisch: 1935 the IBM present the "IBM 601", it was a Punch card machine, which did 1 multiplicate per 1 second. This was the first computer, not the american way. ---Green_Link~~

what is a computer?

The first sentence should be something like: "A computer is an information processing machine which is capable of simulating any other information processing machine that can fit into its memory." There are three salient parts to the definition:

 -information processing machine
 -capable of simulating any other ( like a Universal Turing Machine )
 -can be built in real life, so can't have infinite memory ( unlike a Universal Turing Machine )

Currently the first sentence of the article says "A computer is a machine that manipulates data according to a list of instructions", which is only one particular (but dominant) category of computer architecture -- Instruction Set Architecture. Other real life categories which are actually sold are:

 parallel/multi-core -- one computer processes many lists of instructions in parallel
 reconfigurable/FPGA -- the computer is specialized for simulating any logic network

And some other classes which have only had prototypes:

 stream processors
 cellular automata simulators (probably only one of these was ever made (Margolis))
 dna computer  —Preceding unsigned comment added by 70.20.219.7 (talk) 03:31, 25 January 2008 (UTC) 

While your opening would probably stand up better as a formal definition, I'm not sure that's the best route to follow for an article which is intended to be an accessible introduction to computers. Remember, this article isn't about theories of computation or computability, but about "computers". The term "computer" has a vernacular meaning to society which is every bit as significant as the formal basis. The writing of the article tries to balance these two worlds by introducing computers in fairly familiar terms and then branching out slightly into instruction set (or Von Neumann) architecture. I believe this is a good approach because, as you state, this is the dominant realization of computers and will cover most anything that a typical person will think of as a computer (thread-level parallelism really doesn't break significantly from the "list of instructions" concept, either). With some of your examples (stream processors, special-purpose logic and DSP, DNA computing, etc), there's probably a good bit that can be said about whether these even are computers (the classical "where is the line between a computer and a calculator" question). We run into the issue of a heavily overloaded term in "computer", so we took the tact of making an article as accessible yet informative as possible to a general reader. I really think it would only complicate matters to try to introduce much computing theory in this article, especially since there are a lot of other articles dedicated to the theoretical aspects of computers. -- 74.160.99.252 (talk) 19:07, 11 February 2008 (UTC)

A computer can't be a machine, because the Wikipedia entry for machine excludes computers.Heikediguoren (talk) 21:14, 10 July 2008 (UTC)

The Wiki article for machine is in grave error and should be corrected; analog and digital computers both fall under the broader category of "machines". See Association for Computing Machinery, "the world's first scientific and educational computing society" (and still going strong).

The 3rd edition of the Concise Encyclopedia of Science and Technology (Sybil P. Parker ed., 1994, McGraw-Hill) defines "computer" as "A device that receives, processes and presents information. The two basic types of computers are analog and digital." (Note: A computer doesn't require "a list of instructions".) A broad definition indeed, but the introductory paragraph can quickly set aside the analog variety, which are still in heavy use, although we don't commonly think of them as "computers". Any analog meter, gage, motor driven clock, speedometer, odometer, etc. qualifies as a computer.

I'm not sure "Modern computers are based on tiny integrated circuits…" is the proper phrasing. How about, "Modern electronic computers rely on integrated circuits…" The CPUs in PCs and Macs aren't so "tiny" – it's a relative term anyway.

Btw, the caption that reads, "Microprocessors are miniaturized devices that often implement stored program CPUs" is all wrong; it doesn't even make sense. Microprocessors are literally integrated circuit (as opposed to discrete circuit) electronic computers – computers on a chip. And "central processing unit" should appear earlier in the text. As is, we see "CPU" before we're told what the letters stand for.

Otherwise, nice work guys!

Cheers, Rico402 (talk) 10:16, 11 July 2008 (UTC)

Wristwatch computer

I removed the image - from the image description page, it appears it is a painted image, not a real product. If the image is re-inserted, we need a reliable reference. --Janke | Talk 11:05, 3 February 2008 (UTC)

Defining trait(s) of a computer

The article states:

"Nearly all modern computers implement some form of the stored program architecture, making it the single trait by which the word "computer" is now defined."

This is unreferenced, and to me this seems wrong -- I would say that Turing Completeness is also an essential trait of a "real computer". Is there some basis for saying that stored program control is sufficient?

The article also uses the term "Turing Complete", without defining it. I would suggest a brief explanation of this important concept, and then include it in the "trait by which the word "computer" is now defined." bit. What do people think? — Johan the Ghost _seance 16:55, 10 February 2008 (UTC)

Gottfried Wilhelm Leibniz should be mentioned as he invented the binary system and built mechanical calculators as well. —Preceding unsigned comment added by 84.151.59.187 (talk) 02:19, 17 April 2008 (UTC) Comupters are a very kool invention because u can go on the internet and find what u want or need. —Preceding unsigned comment added by 216.83.96.51 (talk) 13:31, 8 May 2008 (UTC)

"Form factor"

The expression "form factor" is used in many Wikipedia articles on computers, and linked to Form factor (which is a disambiguation page though not labelled as such). This term apparently has several different meanings. One usage seems to be the "footprint" or overall physical size of the computer. This usage seems to be implied in many of our articles, however it is not given on the page Form factor (In other words, where this usage is intended the link is wrong).
Could we please:

• (A) Provide this definition at Form factor, and an article for this meaning if appropriate
• (B) In all articles that mention "form factor", clarify which meaning is intended, as appropriate

-- Writtenonsand (talk) 05:24, 21 May 2008 (UTC)

what is computer

please inform —Preceding unsigned comment added by 164.100.214.116 (talk) 12:27, 24 May 2008 (UTC) computer helps many people to type information and to research —Preceding unsigned comment added by 219.77.75.33 (talk) 08:38, 7 June 2008 (UTC)

Computers

Computers are a machine part of the Education, Comunication and entertainment catorgory and they were invented by J.H. smith. and was invented around 1972 or behind that —Preceding unsigned comment added by 58.160.32.102 (talk) 08:54, 9 June 2008 (UTC)

Computer <> Digital computer

A internal link could profitably, for the curious, be made to Analog computer, and perhaps - for completude - to Stochastic computer 89.224.147.179 (talk) 09:56, 22 June 2008 (UTC)

computer

when the computer exist? —Preceding unsigned comment added by 60.50.238.22 (talk) 09:44, 26 July 2008 (UTC)

Not all stored program computers have a program counter.

The control unit section of this article contains this text "A key component common to all CPUs is the program counter". This is almost correct but I think it should be changed to say A key component common to almost all CPUs is the program counter". The one exception I know of is the ICT 1300 series which have three control registers CR1,CR2 and CR3. After a normal single length instruction is executed in CR1 then CR3 is moved into CR2 and CR2 moved to CR1 and CR1 has one added to it and is moved to CR3. In normal operation (though nothing in hardware forces this) there is at least one unconditional jump instruction in one of the control registers. When one is executed in CR1 then CR1 and CR2 get loaded from core memory and CR3 receives a copy of the original jump instruction with one added. The previous contents of CR2 and CR3 are stored in another register where they are available as a return link for subroutines. When a conditional jump is executed, much the same happens except CR3 receives an incremented version of the jump but with the condition made into always true, that it it becomes an unconditional jump.

When executing a program with two subroutine jumps immediately following one another, all three control registers contain unconditional jump instructions. In this state, it is impossible to point at one of the control registers and say that is the program counter. It sort of has a program counter but it flits between registers and I suppose sometimes you could say there are three program counters. This avoids having any separate logic to implement the fetch cycle and also avoids having to have an extra bit in a program counter to allow for 24 bit instructions in a 48 bit word machine which has no addressable portions of a word.

If you prefer, an alternative wording would be "A key component common to all modern CPUs is the program counter" as the five ton ICT 1301 were built in 1962-5 and are in no way modern, though as over 155 were built, they were quite a large proportion of the computers of their day, certainly in the UK. I should add that the number 155 is because I have part of machine number 155 as well as all of machines numbered 6 and 75, so there could be considerable more than 155.

86.146.160.196 (talk) 18:48, 27 August 2008 (UTC)Roger Holmes