On Aug 18, 12:30 pm, Elizabeth D Rather <erat...@forth.com> wrote: > On 8/18/10 12:09 AM, spinoza1111 wrote: > > > On Aug 18, 1:21 am, Standish P<stnd...@gmail.com> wrote: > >>> Garbage collection doesn't use a stack. It uses a "heap", which is in > >>> the abstract a collection of memory blocks of different lengths, > >>> divided into two lists, generally represented as linked lists: > > >>> 1. A list of blocks that are free and may be used to store new data > > >>> 2. A list of blocks that are in use, or haven't been freed (yet) > > >> Is this all that a heap is or is there more to it ? I have been > >> looking for simple but complete explanation of heap for a while and > >> not gotten to it. I think I am looking for a stack allocation on the > >> same pattern. In a disk, a file is fragmented in many contiguous > >> blocks and is accessed automatically. > > Stacks (at least as far as Forth uses them) and heaps are fundamentally > different things. > > ... > > >>> However, data structures of variable size, or data structures that > >>> merely take up a lot of space, don't play nice with others on the > >>> stack, so, we place their address on the stack and store them in > >>> another place, which was named the heap, probably, as a sort of > >>> witticism. > > In Forth, they go in "data space", which might or might not be in the > dictionary, and is almost never in a dynamically managed heap; certainly > not on a stack. > ... > > > > > No, they're not. Stack based languages have seen better days and Forth > > (and the SL/1 language I supported with compilers at Bell-Northern > > Research) were last in fashion in the 1970s. Processors seldom could > > multitask, so it wasn't recognized that the stack could be a > > performance bottleneck, where stack operations cannot be pipelined or > > executed in parallel. >
> Lol. Forth supported multitasking on every processor it was implemented > on in the 70's, with blazing speed compared to competitive techniques. > I have never seen stack operations to be a bottleneck. > > > > Forth had a snowball's chance because it forces ordinary programmers > > to think in Reverse Polish notation and is for the above reasons hard > > to pipeline, although of course it can be pipelined. > > Mostly it had a "snowball's chance" because it was never picked up by > the CS gurus who, AFAIK, never really took a serious look at it. Its quite possible that the criticism is unfair, but dont you think that in part some responsibility must be borne by your organization in not doing a good job of education ? I have looked at this book you authored in the past few weeks and found a link for your convenience now. This is entitled Advanced ..... http://www.amazon.com/Forth-Application-Techniques-5th-Notebook/dp/1419685767/ref=sr_1_1?ie=UTF8&s=books&qid=1282175842&sr=8-1#reader_1419685767 Show me on what page does it explain how Forth implements dynamic binding or lexical binding and takes care of the scope of definition of the "nouns" ? Provide me with a link, if you kindly would, that can take me to a tutorial of Forth internals or discusses this issue. > Cheers, > Elizabeth She is quite humble. Take a look at this page, http://www.forth.com/resources/evolution/index.html She is currently the number 1 in the forth world and if there was a nobel prize in forth, it would go to these three. Authors Elizabeth D. Rather FORTH, Inc. 5959 W. Century Blvd. Suite 700 Los Angeles, CA 90045 Elizabeth Rather is the co-founder of FORTH, Inc. and is a leading expert in the Forth programming language. Elizabeth was a colleague of Chuck Moore back when he worked at NRAO in the early 1970s. During his development of Forth, she became the second ever Forth programmer. Since then, she has become a leading expert in the language and one of its main proponents. Elizabeth was the chair of the ANSI Technical Committee that produced the ANSI Standard for Forth (1994). She is an author of several books on Forth and gives regular training seminars on its usage. Donald R. Colburn c/o Digital Media Magic 14712 Westbury Rd. Rockville, MD 20853 Don Colburn was one of the earliest Forth users. He was one of the founders of the Forth Interest Group, and contributed to the development of the first public-domain figForth. Subsequently, he founded Creative Solutions, Inc. (CSI), which introduced MacForth™ in 1984. MacForth was the first programming language capable of running on the Macintosh when it was first introduced. Don was a member of the ANSI Technical Committee that produced the ANSI Standard for Forth (1994). He died in 2009. Charles H. Moore Computer Cowboys 40 Cedar Lane P.O. Box 127 Sierra City, CA 96125 Chuck Moore is Chairman and CTO of Green Arrays, Inc. He co-founded FORTH, Inc., in 1971 and went on to develop a Forth-based chip (RTX2000) in the mid 1980s, derivatives of which are still being used widely by NASA. At Computer Cowboys, Mr. Moore designed the Sh-Boom microprocessor and then co-founded iTv, an Internet Appliance manufacturer. During the 1990s, he used his own CAD software to design several custom VLSI chips, including the F21 processor with a network interface. More recently, he invented colorForth and ported his VLSI design tools to it. Moore served as CTO for IntellaSys during development of the S40 multi-computer chip. -- http://mail.python.org/mailman/listinfo/python-list
