From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Sun, 6 Sep 2009 01:37:32 +0100 From: Eris Discordia To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net> Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Subject: Re: [9fans] nice quote Topicbox-Message-UUID: 65cdc420-ead5-11e9-9d60-3106f5b1d025 > so you're saying that the table in this section is wrong? > > http://en.wikipedia.org/wiki/Computer#History_of_computing > > if it is and you can back it up, i sugeest you fix wikipedia. It isn't wrong. The exact wording from "The First Computers: History and Architectures"=20 goes: > The instruction most conspicuously absent from the instruction set of the > Z3 is conditional branching. [...] but there is no straightforward way to > implement conditional sequences of instructions. However, we will show > later than conditional branching can be simulated on this machine. On the other hand, Wikipedia's article on Plankalkuel says: > Plankalk=C3=BCl drew comparisons to APL and relational algebra. It = includes > assignment statements, subroutines, conditional statements, iteration, > floating point arithmetic, arrays, hierarchical record structures, > assertions, exception handling, and other advanced features such as > goal-directed execution. -- In other words, both statements are correct. Z3 did not have conditional=20 branching (given the type of store it used it would be too hard), however=20 Plankalkuel did provision conditionals, invocation, and subroutines--all=20 that is necessary to implement conditional branching. --On Saturday, September 05, 2009 20:17 -0400 erik quanstrom=20 wrote: >> I wasn't, in this case at least, implying something not backed by firm >> evidence. Conditional branching embodied in actual computers goes back >> to Plankalkuel on Z3. The idea is as early as Babbage. It comes as >> natural even to first-timers, following much more difficult conception >> of a notion of control flow, that there must be a manner of >> conditionally passing it around. > > so you're saying that the table in this section is wrong? > > http://en.wikipedia.org/wiki/Computer#History_of_computing > > if it is and you can back it up, i sugeest you fix wikipedia. > > - erik >