Talk:74181

message: If you are aware of other computers or devices that used the 74181 or 74S181 please add them to the list. 74s181 13:51, 27 October 2007 (UTC)
replies: text: hints at some of these things. -- RoySmith (talk) 02:46, 28 October 2007 (UTC)

text: Also look at  -- RoySmith (talk) 02:51, 28 October 2007 (UTC)

text: Here's another one .  They require a little interpretation, but as first-hand recollections of the man himself, I don't see how you're going to get much more reliable than than.  -- RoySmith (talk) 02:59, 28 October 2007 (UTC)
thread_title: Comment 1

message: The  template does not require an entry on the talk page; it's just a suggestion. I've replaced it again, since "today's microprocessors" is a temporal phrase. The microprocessors of "today" evolve pretty continuously with new releases, designs, and fabrication processes. As worded, the article is not clear in what it means, and is using this vague wording to avoid being specific and accurate. The uncited text in the "today" section should explain the specific transition involved, and what evolution caused it. Otherwise, it should be removed from the article. -- Mikeblas 01:44, 2 November 2007 (UTC)
replies: text: I think you're being a bit silly with this   business.  It is important to provide a time frame when a statement may only be transiently true.  If I say, Super Gonzo Space Invaders is the world's best selling video game, that's the kind of statement which needs to be qualified with, as of November 2007, because it's the sort of thing which changes often.  On the other hand, Antarctica contains the statement, Antarctica is Earth's southernmost continent.  Technically, that's only true for now.  In another 200 million years, the plates will move around and it may no longer be true.  Would you put a  tag on Antarctica?  No, of course not.  The same logic applies here.  The 74181, however notable it is for its historic uses, is effectively obsolete.  It will never again become cost-competitive with contemporary modern chips.  Yes, it would be useful and interesting for the article to explore the exact history of when the 74181 faded from being the top of the heap, but the lack of such an exploration does not detract from the current statement.  I'm removing the tag.  -- RoySmith (talk) 14:05, 2 November 2007 (UTC)
replies: text: Your analogy doesn't apply very well because of the obvious difference in time scope. The "today's" problem does detract from the article because it's not concrete when a concrete statement can easily be written. As such, I've taken a crack at resolving the temporal problems in this section myself. -- Mikeblas 14:30, 2 November 2007 (UTC)

text: See Killer micro -- RoySmith (talk) 19:10, 2 November 2007 (UTC)
thread_title:  When 

message: Although "4 bit slice of an arithmetic logic unit" may sound more grammatically correct, it isn't quite factually correct.  It isn't a 'slice' of an 'ALU'.  See Bit slicing.  It is a full blown 4 bit wide ALU that is designed to be connected to with other identical parts for larger word lengths, that is what 'bit slice' means. 
Let's talk if you disagree with the current wording, "The 74181 is a bit slice arithmetic logic unit (ALU), implemented as a 7400 series TTL integrated circuit. " 74s181 00:16, 3 November 2007 (UTC)
thread_title:  4 bit slice of an arithmetic logic unit  

message: I have never heard of a microprocessor without an integrated ALU.  I think this statement comes from a misunderstanding of what an ALU is, or what a microprocessor is, or both.
There are various reasons why the '181 is no longer 'commercially viable' compared to microprocessors today.
#A CPU built using the 74181 requires many components, even the Pathetic Instruction Set Computer (PISC) requires 22 chips.  A nicroprocessor is a single component, it is inherently smaller, more reliable and cheaper to mass produce.
#A CPU built using the 74181 will use more power and dissipate more heat than any modern microprocessor of equal computing power. 
#A CPU built using the 74181 or even faster discrete logic families (like ECL) is limited by speed of light delays inherent in the size of the chips and the spacing between them.  Believe it or not, part of the reason that today's microprocessors are able to run faster than the fastest supercomputers built from individual components (like the '181) is because all the parts of the microprocessor CPU are within a few millimeters of each other.  
Even though #1 and #2 were true from the very beginning of the microprocessor age, computers based on the '181 and later TTL and ECL bit slice components still were commercially viable for several years because the first microprocessors were so slow.  The 8 bit 8080 could execute up to 500,000 instructions per second and was popular from 1975 until the IBM PC came out in 1980.  The 16 bit Data General Nova 3, a popular minicomputer of that time period based on the '181 executed instructions in about 800 nanoseconds, or about 1.2 million instructions per second. Not only was it three times faster in raw instruction execution, it was a true 16 bit computer, my experience was that it was 10-20 times faster when running real applications. But the IBM AT (based on the 80286) came close to the Nova 3 in performance, supported more RAM, and was 1/10th the cost ($50,000 for a Nova 3 with hard drive, terminal, and printer, vs $5,000 for a similarly equipped IBM AT). 74s181 01:26, 3 November 2007 (UTC)
thread_title:  microprocessors that have integrated ALUs 

message: I've removed this.  A message at http://www.classiccmp.org/pipermail/cctalk/1999-April.txt.gz indicates that the 4052 used the 2901, not the 74181.  -- RoySmith (talk) 02:35, 3 November 2007 (UTC)
thread_title:  Tek 4052 

message: There is only so much time in the day, and there are priorities in my life that need more time and attention right now.  So, while I don't expect to be completely absent from Wikipedia, don't be surprised if days go by without any contributions from me. 74s181 14:19, 14 November 2007 (UTC)
thread_title:  Less active. 

message: The article lacks a history of 74181, such as: who or which manufacturer developed it first etc. Cogiati (talk) 15:07, 17 June 2011 (UTC)
thread_title:  History of 74181 

message: The logic table is wrong and incomplete.
It is wrong because, for active-low, the signal "L" from figure 1 of the data sheet translates
to logical one, not to zero.
It is incomplete gives half the data, because only half the data is given (Cn=0 for active-low,
Cn=1 for active-high).
--Trex4321 (talk) 16:07, 12 September 2021 (UTC)
thread_title:  Logic table is wrong