So we decide to scale our input to feet and inches rather than merely to whole feet. By the way, we could as easily have designed input to be in tenths of an inch with a decimal point, like this:. In writing the definition of PILE, we must try to maintain the maximum number of places of precision without overflowing 15 bits. According to the formula, the first thing we must do is cube the argument. Even to square produces ,, which exceeds the capacity of single-length arithmetic using bit cells.
Thus the phrase. Using as our test argument, the above phrase will yield But our pile may be as small as 5 feet, which when squared is only To divide by would produce a zero in integer arithmetic, which suggests that we are scaling down too much.
To retain the maximum accuracy, we should scale down no more than necessary. Thus we will begin our definition of PILE with the phrase. The integer result at this stage will be scaled to one place to the right of the decimal point for Now we must cube the argument. We find that by using as our divisor, we can stay just within single-length range. Our result at this stage will be scaled to one place to the left of the decimal point for According to our formula, we must multiply our argument by pi.
We know that we can do this in Forth with the phrase. Next we must divide our argument by the tangent squared, which we can do by dividing the argument by the tangent twice. Because our tangent is scaled to three decimal places, to divide by the tangent we multiply by and divide by the table value. This article makes me want to try. The HP48 emulator is the first thing I installed on my android phone…. Not in Occam and a few other languages. For a programmer switching between different languages different precedence rules can be a PITA and cause bugs that are nearly impossible to spot.
OTOH switching between a language with precedence and another without can also cause problems. I worked for a firm in the mid to mids that had PL1 as the complied high level language on and Z80 micros. It was compiled to a pseudo-code that I now realize was forth-based.
The commands were single byes in value from 0 -1F hex, if the byte was in the 20 — FF hex, it was the high byte of a two byte address. Bad timing for eBay Chinese orders. Most of them are shut down for the next 10 days or more and the shipping back log after the Spring Festival will slow things down for another And AliExpress.
I used to buy tons of stuff from that site, but have completely given up on it. Way too much aggravation. I noticed the same about AliExpress vendors lately, but I assumed that it was just bad luck with the last orders.
In I never opened a dispute, but for all of the last 3 orders of a dispute was necessary. I have the same problem. Two of my orders are more than 2. Use Banggood or Taobao. Me too. Last two orders never arrived and the one previous to those took over two months.
I usually go as local as possible. Well, the article will still be there when you get the parts. Or you could patronize one of your local re-sellers for a couple bucks more.
Nothing seems to come anywhere close to Forth in development speed. In assembly-language-only applications have benefited from forming Forth-like structure macros too. They improved my assembly-language productivity and enjoyment. Over the last couple of months I have heard about 3 or 4 different independent implementations of Forth Stack machines from people I know. They were done for performance and can be combined with C or are written in C and assembly.
The big help is the well prepared structure that you have to follow — which saves design time as well. But Forth or similar is not for everybody. I use FlashForth on the Arduino Uno. It seems a very stable implementation and is a joy to use. It can be downloaded from flashforth. Take care of the fuses settings, and you need intercharacter and newline delays on the Arduino Uno unfortunately.
You should be using them anyway. But smart compilers optimize a lot of that out, taking the advantage away. Thanks to all people that replied, I have read through your comments with interest. Arduino is something that everyone has, so it would be easy to compare performances of stock Arduino C vs Forth.
I will look at AmForth tomorrow. That itself should translate to more speed. I actually really like the way Mecrisp handles flash vs RAM, though. You have plenty of space in RAM to play around, and when you get something you like, burn it to flash and reset: all the mistakes left over in RAM get cleared, and the functions that worked remain.
It provides a quasi-clean-slate that makes developing and testing code incrementally very pleasant. Feature, not a bug. I got Forth up and running on an arduino, setup script available on the first search hit for forthduino. However, these languages are no longer popular since computers that can run GNU gcc cross-compiler toolchains are now ubiquitous.
Lisp was written by Aliens for Aliens, if someone recommends this… check for brace shaped antennas… seriously… ;-. It makes for pretty good assembly after you get use to RPN assembly, which is more natural anyway.
And you can switch radix at will and dump that 0x notation. Fun in Forth: interactive machine language. You can just push the opcodes into RAM and run them. A vegan, a person who just quite smoking and a Forth lover walked into a bar.
How do I know? They immediately told everyone around them. I wrote this piece with a bit of self-loathing. Some Forth folks are way too enthusiastic and fail to see its flaws.
Searching about Forth online will bring up a lot of that. But when you go looking for projects or example working code, you come up empty.
I promise the next article will be all application, and no proselytizing. Long ago, my then employer evaluated the RTX Forth chip. The company had a lot of in-house Forth expertise.
IIRC the design win nevertheless went to the I wrote the first 25 Project Euler problems in Forth, when I wanted to learn. I believe that each of the programs works. It worked out very nicely. This was the third ATE setup I had done. I found this Forth tutorial with built in interpreter a while back. It is by a fellow named Nick Morgan. FORTRAN passes things by reference that is, it passes a pointer to the value ; modifying a parameter changed the location in which the compiler had stashed the constant.
When accessing main memory, the cache-based FORTH would figure out which cache line was going to get clobbered and squirrel away a copy before doing the access. Restoring the line from the saved copy repaired the damage. Forth is also the basis for PostScript and thus PDF , which made it a good stepping stone for figuring out those graphics calls. I had fun running fractals on an OG LaserWriter that could take an hour to print. Warnock denies any Forth influence, no matter how obvious, despite the FIG conventions happening near him.
Both Forth and Postscript are stack based, what other obvious similarities are there? The stack operators and their names. Just about everything really.
Warnock just spelled them out and made everything floating point. Postscript is a great accomplishment. I just nev3er understood why he denied knowing Anything about Forth. The Forth Interest Group was right there. What can I say? It was hard to believe him. My favorite part of this article is that there is no break in it.
It reminds me of HAD back when there was one hack per day and it was worth reading the summary. Keep it up Elliot. I feel like there used to be a reason for Forth but that time has come and gone. One could argue that Forth is the concept of a virtual machine and in that way lives on but beyond that it seems like a fairly dead language.
If you really want to learn about a microcontroller then you should learn the instruction set for that architecture. Pretty neat, if inefficient. That is true in a lot of ways. But you still really need a bunch of tools like GCC, GDB, and Eclipse and a very fast box to make the response time as good as interactively using Forth natively on a 1MHz micro to figure out the details of a new interface.
Not so much the compile time but the time to send the code over to the micro. Or the time to take to edit the code to put in a debug routine before you compile and download. So how does that work? Yes, stores in the flash. It seems to work well for my ADD kids, rather than doing the wait a minute while I edit this code in the tiny arduino editor and wait for it to download, instead its immediate when you make a change.
It has to save to flash to be worth anything. The interpreter might run from flash or RAM depending on the advantages. The party that navigates through the pointers that make up the code, the inner interpreter, is about 20 instructions long in a 65C02 and on an ARM it cam be 2 instructions provided you have the ARM instruction set with conditional execution of all instructions.
In that case, one might as well stick the 2 instructions on the end of every definition to avoid disturbing the pipeline. Analysis of complex code shows that stack depths very rarely exceed 16 entries.
So stack and interpreter and space for variables and buffers is not very much. On a I use that since it is close enough to AVR and a lot of work was done on the stacks and a bunch of variables and all that fit in an available portion of the byte zero page on an Apple II. Expandable to 4K and was used for a lot of industrial control.
One big difference with C unless specially modified Forth is string handling. Forth uses counted strings. They start with a length. C was created on mainframes with tape archives. In fact, the. So C was designed to deal with streams of data of unknown length — I should say the C lib. With the Forth method you can allocate space because you know how much you need, and there are no forbidden values for string data, like EOF. The string input and output is Pretty strange if you are used to C.
Modern Forths almost always have string handling extensions that match the C per-processor. When you want to change radix or base, you just do it. And you print the top of stack TOS with a period. A good version would save the current radix, set decimal perhaps so you can use a number for the base that makes sense to you, then restores the current base.
Well, I did not intend to write so much. I suspect Elliott intends to cover some of this in better form. It has been a very long time. I think I need more Forth. When I go do a build on fresh pull from trunk it takes several minutes. I see so many people complain about this on other forums too.
If yo move off of windows doe development then most of the slow wait goes away. On application code it is not noticeable, especially after the first compile and stuff is in cache. OTOH, transmitting compiled binaries to a micro takes significant time regardless of the tools used. It is still very relevant for robotics. The reason is that you can test every operation as you add it to your code.
Very little of a forth system need or should be written in assembler. Most of it is written in forth. So ports are relatively low cost. Because the primitives are so simple, an experienced person can port forth about as fast as they can read the MCU documentation.
Yes, people have written almost everything you can imagine in forth. In many cases because they could. Forth will be obsolete when robotics becomes obsolete. Great article Elliot.
Yeah, I know. Moore used to tell that he developed it to control looms at Monsanto? Wikipedia says telescopes. I took a class at Forth, Inc in from Liz Rather. Never heard anything about looms. Chuck did implement something forth-ish in Fortran before Kitt Peak. One of his motivations was a portable toolkit he could carry from job to job. Chuck did have a forth-ish implementation in Fortran. His motivation was to have a portable toolkit of tools he could carry with him from job to job.
That risked copyright problem but he managed. Yes, your work for a company is copyrighted by them so taking it elsewhere is a problem. Some exceptions for consultants, etc. This was a tenacious problem when it came to building Forth engine hardware, which he worked on several times.
There was a trail of old associates and employers who all wanted a piece of the action. He wrote complete CAD and simulation suites in a new Forth he designed for that purpose.
It was cool stuff, with objects that knew their impedance and other properties. Signal prorogation down traces could be watched in slow motion, etc. Very cool. There is no intermediate layer. I presume Chuck Moore also lives in this world.
How the heck is it that Forth is more portable than C?!?! I need to look at punyforth again. The newest interest of Chuck Moore the inventor of Forth who turns 79 this year, seems to be GreenArrays where he has stack processors on a single IC, for massively parallel embedded applications. Each of the processors on the IC runs Forth instructions in as little as 1.
There are some parts of ANS Forth that present extra overhead in order to make it more portable across a wide range of processors. My personal opinion is that they may have taken this too far. We must consider the programmer s and platform s involved, and decide on a good balance between portability and optimization. I personally prefer more optimization at the expense of portability. Greater optimization means a particular processor can be used for a wider range of jobs anyway, which could in itself reduce the need for portability.
If code is taken from one platform to another, modifications may be needed, but they should be rather minor. I agree. ANS effectively killed Forth by making it too big and clever. ANS was like reading a philosophy and linguistics paper with syntax this and run-time semantics that. The standards club was just interested in a much different project than the serious Forth user.
Words may be defined in terms of previously defined words or in machine code using the embedded assembler. They are also equivalent to commands in other languages — Forth blurs the distinction between linguistic elements and functional elements.
Words are referenced either from the keyboard or in program source by name. Except for these, there are no special characters that cannot be included in a word or start a word, although many programming teams adopt naming conventions to improve readability.
Words encountered in text fall into three categories: defined words i. There are no explicit typing mechanisms in Forth, a feature which sometimes surprises newcomers, but is generally admired by experienced Forth programmers.
These principles may be summarized as follows:. Every program is described as a linear sequence of self-contained modules. A module has one entry point and one exit point and ideally performs one function, given a set of inputs and a set of outputs. These principles were first called to his attention in by Rather, who received several comments on the apparent relationship between Forth and structured programming in seminars she was giving on Forth.
This tiny program included disk or tape and terminal drivers and the ability to search and build the dictionary. This nucleus was then used to compile from source the balance of the programming environment, including the assembler, editor, multiuser support and several hundred general commands.
Booting the system, including compiling most of it from source into executable form, took only a few seconds. A metacompiler, also written in Forth, was used to compile the nucleus. The entire source for the system was about 40 pages long. A Forth program is organized into an extensible dictionary that occupies almost all the memory used by the system. The dictionary is classically implemented as a linked list of variable-length items, each of which defines a word.
The content of each definition depends upon the type of word data item, constant, sequence of operations, etc. On multi-user Forth systems individual users may have private dictionaries, each of which is connected to a shared, re-entrant system dictionary.
Forth maintains two push-down stacks, or LIFO lists on a multiprogrammed version, a pair for each task. These are used to pass data between Forth words and for controlling logical flow. Extended-precision numbers occupy two stack positions, with the most significant part on top. Items on either stack may be addresses or data items of various kinds.
Stacks are of indefinite size, and usually grow towards low memory. Since results of operations are left on the stack, operations may be strung together effortlessly, and there is little need to define variables to use for temporary storage. Forth is an interpretive system, in that program execution is typically controlled by a small machine-code routine often only two or three instructions interpreting lists of pointers or tokens for abstract machine functions.
The text interpreter extracts strings separated by spaces from the terminal or mass storage, looking each word up in the dictionary.
If a word is found it is executed by invoking the address interpreter, which processes a string of addresses compiled in a word definition by executing the definition pointed to by each. The text is not stored in memory, even in condensed form. If a word is not found, the system attempts to convert it as a number and push it onto the stack. If number conversion fails due to a non-numeric character , the interpreter aborts with an error message.
The address interpreter has two important properties. First, it is fast, often requiring as few as one or two machine instructions per address. In contrast, a subroutine call constructed by most compilers requires instructions for handling the calling sequence before and after a CALL or JSR instruction and address, and typically save and restore registers within the subroutine.
Most Forth systems include a macro assembler for the CPU on which they run. The assembler lets the programmer use explicit CPU-dependent code in manageable pieces with machine-independent interfacing conventions.
To move an application to a different processor requires re-coding only the CODE words, which will interact with other Forth words in exactly the same manner. In a classical Forth assembler, the op-code itself is a Forth word which assembles the instruction according to operands passed on the stack giving the addressing information. This leads to a format in which the addressing mode specifiers precede the op-code consistent with the postfix notation used elsewhere in Forth.
Registers were generally referred to by number, except for registers assigned to key internal system functions. For example, the stack pointer is usually in a register called S. One would address the second item on a two-byte wide stack using the phrase 2 S. Forth assemblers support structured programming in the same way that high-level Forth does. Such structures are easy to implement because the stack is available during assembly to carry addressing information.
Conventional assemblers leave the code in a file, which must be integrated with code in files from high-level language compilers if any by a linker before the resultant program can be loaded into memory for testing. The resident Forth assembler assembles the code directly into memory in executable form, thus avoiding the linking step.
The Forth assembler is used to write short, named routines that function just like high-level Forth words: when the name of the routine is invoked, it will be executed. Like other Forth routines, code routines expect their arguments on the stack and leave their results there.
Within code a programmer may refer to constants to get a value , variables to get an address or other defined data types. Code routines may be called from high-level definitions just as other Forth words, but do not themselves call high-level or code definitions. These features enable Forth programmers to write code in short, easily testable modules that are automatically integrated into an application.
Programming is fully structured, with consistent rules of usage and user interface for both assembler and high-level programming. Most new words can be tested simply by placing input values on the stack, typing the word to be tested and validating the result left on the stack by displaying it. The result is complete control of the computer, high performance where needed, and overall shortening of development time due to interactive programming at all levels. The block size was chosen as a convenient standard across disks whose sector sizes vary.
At least two block buffers are maintained in memory, and the block management algorithm makes it appear that all blocks are in memory at all times. A buffer whose contents is changed is marked so that when it needs to be reused its block is automatically written out. This algorithm provides a convenient form of virtual memory for data and source storage, with a minimum number of physical disk accesses required. In native Forths, the block system is both fast and reliable, as the disk driver computes the physical address of the block from its number — no directory is required.
In disk-intensive applications, performance can be enhanced by adding more buffers, so more blocks will be found in memory; the buffers become a disk cache. In the s, Forth systems became available running under conventional OSs, as we shall see. Many of these support blocks within host OS files, although some have abandoned blocks altogether. As blocks provide a compatible means of accessing mass storage across both native and non-native systems, ANS Forth Section 5.
The earliest Forth systems supported multiprogramming, in that the computer could execute multiple concurrent program sequences. In , Moore extended this capability to support multiple users, each with a terminal and independent sub-dictionaries and stacks.
The entity executing one of these program sequences or supporting a user is referred to as a task. Interrupts were directly vectored to the response code using an assembler macro, without intervention by the Forth executive. Interrupt code performed only the most time-critical operations e.
The task would actually resume operation the next time it was encountered in the round-robin task loop, at which time it would complete any high-level processing occasioned by the event and continue its work.
Table 2. Performance comparisons of several real-time OSs on a M [Cox, ]. Times were normalized to a 10 MHz Consultant Bill Cox pointed out [Cox, ] that a non-preemptive algorithm such as this has several advantages. First, the task scheduler itself is simpler and faster, taking as little as one machine instruction per task.
Third, task code can be written with the knowledge of exactly when the task does or does not control the CPU, and management of shared resources is considerably simplified. Cox compared the performance of several real-time OSs; the results are given in Table 2. Tasks were constructed when the system was booted, and each was given a fixed memory allocation adequate to the functions it was intended to perform. As re-booting took only a few seconds, it was easy to reconfigure a task.
Until the late s, few minicomputers offered floating point arithmetic — indeed, many lacked hardware multiply and divide. From the beginning, however, Forth was used for computationally intensive work. This reflects the way most multiply and divide machine instructions work, and enables calculations such as:.
The ability to multiply by a ratio is ideal for calibration and scaling, as well as rational approximations. A rich set of single, double and mixed-precision operations such as these make integer arithmetic much more usable than it is in most languages.
Moore expressed angles internally as bit, bit or bit fixed-point binary fractions. He provided a set of primitives to convert to and from angle formats e. Operations such as the Fast Fourier Transform were provided in some applications, built on specialized primitives supporting complex numbers as scaled integer pairs. Today fast floating-point processors are common. Basically, he wanted to assume full responsibility for manipulating data objects in whatever way he wished.
The nature of the values kept in constants and variables was entirely arbitrary; there is normally no explicit type checking. Strings are normally kept in memory with their length in the first byte. The address of this structure, or the address and length of the actual string, can be passed on the stack. Forth also provides tools to enable the programmer to build new defining words, specifying a custom behavior both at compile time e. One side effect of this was the growth of an active and enthusiastic group of hobbyists who fell in love with Forth.
At the same time, Moore himself was becoming increasingly drawn toward hardware implementations of Forth, and less involved in software production at FORTH, Inc. In this section we examine the development of Forth under these diverse new influences. In the late s, Northern California was afire with the early rumblings of the Computer Revolution. Magazines such as Radio Electronics published step-by-step instructions on how to build your own video display terminal, and even how to build your own microcomputer system.
Echoing back to the first generation computers, there was insufficient memory to concurrently support an editor, assembler and linker. Although some BASIC language products were available, they were typically very slow, and incapable of supporting significant programs. Forth had been born and bred to exploit the minimal facilities of resource-constrained systems.
It carried neither the excess baggage of a general solution nor a requirement for an existing file or operating system or significant mass storage. As Forth was used to tackle more and more difficult embedded computer applications, it started to claim the attention of the Northern California homebrew computer enthusiasts. He found Maj. Selzer and Ragsdale subsequently made substantial modifications and improvements to the model, including exploitation of page zero and stack-implicit addressing architectural features in the Many of the enhancements that characterized the later public-domain versions were made during this period, including variable-length name fields and modifications to the dictionary linked-list threading.
A metacompiler on the Jolt could target a significantly changed kernel to a higher address in memory. A replacement bootable image would then be recompiled by the new kernel into the lower boot address, which could then be written out to disk.
At this point, Ragsdale had a system with which to meet his professional needs for embedded security systems. In order to simplify publication and rapid implementation across a wide variety of architectures, a translator was written to convert Forth metacompiler source code into text that, when input to a standard assembler, would replicate the original kernel image. In this way, neither the metacompiler nor its source code needed to be published.
This is an important point. Forth metacompilation is a difficult process to understand completely. It requires the direct manipulation of three distinct execution phases and object areas, and is not something that a casual user wanted or needed. It was the intention of the original team of implementors to thus stimulate the development of compatible Forth systems and the appearance of new vendors of Forth products.
Over the years, volunteers added other platforms and documentation. Today there are several thousand members of the Forth Interest Group in over fifteen countries. Since , FIG has sponsored an annual conference called FORML Forth Modification Laboratory , an educational forum for sharing and discussing new or unproven proposals intended to benefit Forth, and for discussion of technical aspects of Forth. Its proceedings are available from the Forth Interest Group. Apple Computer grew out of the bubbling computer enthusiasm in the San Francisco Bay area, and with it a whole new generation of resource-constrained computers.
Although BASIC was available in ROM, Forth was used to write a number of popular text editors and games on the Apple ][, allowing resident development of significant programs within its scarce memory and disk constraints. It is hard now, with ubiquitous megabytes of memory and disk, to imagine what it was like to develop significant programs on a column wide screen within 16K of memory and K of disk storage. Vendors of low cost Forth systems sprang up almost overnight, each supporting their favorite personal computer, most of them basing their systems on the FIG model.
Numerous commercial and public domain Forth products followed, and significant software product development began. Duncan, ]. In , Maj. A multitasking, multiuser version of this product called MultiForth was demonstrated to Motorola in January, , well ahead of production shipments of the By there were over seventy vendors of Forth systems, ranging from single individuals to multi-million dollar organizations.
This organization sponsored an annual Conference on Forth Applications at the University of Rochester, Rochester NY, and publishes the Journal of Forth Application and Research, a refereed technical periodical on applications of Forth, new developments and techniques, and surveys of specific areas of Forth. Table 3. Some major suppliers of Forth systems, services and related products. Byte Magazine dedicated its August, issue to Forth.
It was their largest-selling issue to date, and was reprinted several times. FIG Forth was optimized for portability rather than performance. Only a very few primitives were coded in assembler, and the rest of the logic was implemented using high-level Forth. As a result it was fairly slow — some operations, such as dictionary searches, were a factor of ten slower than representative commercial implementations. Other internal decisions were similarly made with the neophyte in mind.
This gave a lower collision rate than simple truncation, and was adequate most of the time. But the FIG model used variable-length names up to 31 characters, thereby trading size for user-friendliness. This was somewhat controversial at the time see Fig. The advent of personal computers provided Forth implementers with the incentive to learn to run under a host OS. In , LMI added support for software and hardware floating point, and also pioneered performance enhancements such as native code translation and caching dictionary lookups in a hash table to accelerate dictionary searches.
The advent of non-native Forth implementations introduced an issue that remains controversial in Forth practice today, the use of host OS files for mass storage. There are two main approaches: abandoning traditional blocks altogether in favor of directly manipulating source and data in files, and mapping blocks to host OS files.
The former approach is favored by implementers who are concentrating on systems for a particular OS e. Other novel features included runtime relocation of the executable image and exclusion of word names in runtime systems without metacompilation. MacForth included a seamless programming environment, incorporating screen based text editor, compiler, interpreter, and assembler in under 20k bytes of memory.
The FIG Model was in the public domain, and was ported to a wide variety of computer systems. However, FIG Forth was not representative of all commercial implementations of this era. Commercial vendors tended to be much more performance-conscious, and elected implementation strategies that optimized performance or size rather than porting ease, as we have seen.
Figure 1. Other problems involved the specification for floored division in FORTH and a serious ambiguity in the specification of parameters for certain loop structures. The effect of these incompatibilities was divisive. Although most implementors agreed that FORTH was an improvement and adopted the new standard, there remains a vocal group who never converted, and who remain skeptical of the whole standards process.
Both lucid and entertaining Brodie drew memorable cartoon figures representing important Forth primitives , Starting FORTH was also a thorough introduction to the language. Another major influence in the personal computer marketplace has been the competition between public-domain and commercial versions of Forth.
Versions have been developed by many independent programmers on a wide variety of other platforms. This system is so widespread that many people are led by its name to confuse it with the FORTH standard. In the late s, Tom Zimmer and others produced an even more extensive public-domain system for PCs called F-PC, which includes several megabytes of source code and utilities.
But except for these, most public-domain Forths are rather limited. Public-domain Forths have certainly helped to ensure that Forth is widely known.
The problem is that it is relatively easy to implement your own minimal Forth system. The kernel, after all, is only a few hundred bytes of code…. One of the biggest problems with public-domain and shareware systems is that their libraries are often only partially completed, with sketchy documentation. People who have only seen or used limited public-domain Forth implementations often perceive that Forth itself is a toy. A prospective user is well advised to evaluate a number of both public domain and commercial offerings.
Some were large, such as the ton stretch press used by Lockheed to form panels for the C5B airplane wings in the early s. Some were distributed, such as the roughly networked processors used for an extensive facility management system at the King Khaled International Airport at Ryadh, Saudi Arabia [Rather, ]. Forth has been especially successful in developing firmware for hand-held devices made by companies such as Itron and MSI Data.
As a result, it has been used in a number of satellites and Space Shuttle experiments. Bradley believes [Bradley, ] that Forth was successful for this purpose because it offered:. At least one other major board-level CPU vendor has adopted Open Boot firmware across their product line, and there is a working group developing an IEEE standard for it.
Most embedded systems lack a disk, a terminal, or both, thereby rendering themselves inhospitable to even the leanest Forth programming environment. Nonetheless, some vendors do provide on-board Forths in microcontrollers. But as PCs became ubiquitous, they also became popular as hosts for more comfortable and powerful Forth cross-development environments. These have generally been based on modified versions of the classical Forth metacompilers, adapted to support cross development.
The internal architecture of Forth simulates a computer with two stacks, a set of registers, and other well-defined features.
As a result, it was almost inevitable that someone would attempt to build a hardware representation of the actual Forth computer. The first actual Forth computers were bit-sliced board-level products. The first of these was made by a California company called Standard Logic, in
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