Dual-stack (Forth) processors

Maybe

will be of interest to you

Roman

I can't say for sure exactly what kind of marketing would have helped the RTX succeed. But I can tell you that any effort to pit it against the x86 line was misdirected. The x86 parts were not really embedded chips and I don't recall them being used as such very often. My memory may be failing me at this since this was long before there were chips aimed at the embedded market. But the Z80 and 8085 would have been the main competition for an embedded processor. The x86 line used too much board space and cost too much for most apps.

It is likely that Harris did not understand what you do about the significant factors in embedded, realtime work. It has been more than once that a vendor needed to educate the engineering community about the features that make their products are a better way to go.

--

Rick "rickman" Collins

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yes, the block rams (with registers implemented in those) make FPGA-s have an interesting tradeoff - * you can have a large number of registers with no penalty * you are very limited in number of read/write ports, and adding more does not scale *AT ALL*

I see - just the benchmark numbers only used the simple 8-bit interface.

--
	Sander

+++ Out of cheese error +++

The older Xilinx parts have small LUT based rams that have true 3 port memory. But how they implemented it shows that you can always make a 3 port memory from a pair of two port memories. They tied the two write ports together so that the two RAMs always were written with the same data. But the read ports were kept separate allowing any two words to be read at the same time.

--

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

projects

about a

(EP1C6)

the

of

source

internal

loaded in

the

directly. It

instructions

to

stack,

the

and

needs

register

result

for

forwarding.

FPGA-s

As for a RISC processor you need two read ports and only one write port it is easy (with a little waste) to achieve this with the typical FPAG memories. You have to double the memory and write in both blocks, than you can use two independent read ports. But there are still some minor problems: Current block rams downt allow read during write or unregistered access. This adds more pipeline stages (with more data forwarding) to the design. With only stack spill/fill you can calculate the stack address early in the pipeline and than you don't need extra pipeline stages in a stack based design. And with a 'large' on chip stack it can be seen as a very elegant and simple (no tag rams) data cache.

for

block

different

for

Xilinx

of

interface.

I really should update this web page (It is soo old....)

design

I know it was some time ago now, but only the RTX 2010 had the hardware one-cylce mutiply/accumulate, etc instructions. The RTX 2000/1 had the one-bit 16-cycle multiply/divide instructions.

Someone recently posted (Jan or Feb 04) the urls to get the pdfs of the RTX 2000 manual and RTX 2010 Intersil users guide. I have both of them. If you can't find them on c.l.f. let me know and I'll email them to you.

I also used the Silicon Composer boards, with the RTX 2000s. I used them primarily to test/compile code for our embedded systems, and to play around with for other projects. A good thing about the RTX

2000/10 were they were pin-for-pin compatible, and I could hand code the extra 2010 instructions with the SC development software. Piece of cake.

The 2000/10 were way ahead of their times (as was the original Novix). Not only could you also do 32-to-16 bit squareroots, one-cycle streaming memory instructions, partition memory into USER segments which could be accessed faster than regular ram space, stack partitioning, 3 counter timers, fast external interrupt response, the clock could be completely turned off, and back on again without losing instructions, to run on as littel power as you could get away with.

If only somebody like Motorola had taken hold of these chips. With their fabrication capabilities, and cpu marketing savy, they couldl have really done something with these desigsn. And think about just a 500 MHz RTX type chip know. Even then, the RTX performed at mulitple MIPs times its operating frequency (because of instructions compression - multiple Forth words being performed by one RTX instruction)

But of course, I'm just engaging in ex post factor wishful thinking.

Yours

Jabari

Jabari,

What's annoying about bottom posting?

Bottom-posting-gone-wild with a full thread quoted in the top of the message. Like yours.

At least with top posting I can very quickly click through a bunch of messages and read the new post. With bottom-posting-gone-wild you have to scroll to the bottom of every darn message to find the new text. Not only a waste of bandwidth but annoying as hell. See below for an example.

With top posting, if you are reading through a thread, you can quickly navigate up/down the thread and read it without further calisthenics.

If you want to bottom post (which is appropriate when you need paragraphs to be in context, or to address specific statements) at least take the time to clip and snip the relevant parts of the message you are replying to.

-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Martin Euredjian

To send private email:

0_0_0_0 snipped-for-privacy@pacbell.net where "0_0_0_0_" = "martineu"

which

took

stash

stacks

differences

them.

Imagine if you had to scroll down to here on every new message!!!

When I reply to a top-posted message with a sig -- like yours -- everything below the sig is gone, as here. The _)(*&^%$#@!! news program snips it all silently.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Of course, I can restore what the )(*&^%$#@!! browser snipped by copying and pasting, but I lose a level of quote indentation. Here's a hint to ease your pain: + brings you right to the end in many news readers.

Jerry

-- Engineering is the art of making what you want from things you can get. ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

which

16-cycles. It was >>>> > > rated a 8 MHz (but they could easily run at 10 MHz [which meant it

took

16-bit >>>> > > multiply, a one-cycle 16-bit multiply/accumulate, and a one-cycle >>>> > > 32-bit barrel shift. This was the version that Harris/Intersil based >>>> > > the radhard version upon, which NASA and APL (Applied Physics Lab in >>>> > > Columbia, MD) used for its space missions. They both still have a

stash

stacks

differences

them.

Imagine if you had to scroll down to here on every new message!!!

I never used the 80186 but I have heard from people who did use it in embedded work and later the 386e for embedded was clearly aimed for and used for some embedded work. (though not be me.) Technically comparing RTX to 8085 or Z80 seemed compelling but didn't seem to account for much. (Rocket scientists excepted.)

While you might be right, as we can only guess about such things, I think that since we know that at least Phillip Koopman was working there that they did have people with deep understanding of the significant factors in embedded, realtime work. What I see as a bigger issue is not if they understood such things but if their intended customers understood such things. I suspect that they didn't and that Harris was not able to educate them with their marketing effort. I think that is the real and bigger problem. It was not that they didn't understand, but that they were up against and overwhelmed by pervasive marketing information that was counter to their message.

Perhaps if they had spent billions on marketing to even the playing field they would-could-should have sold more chips, but it would have been a big gamble and one that was unlikely to return sufficient profit to justify it. Instead they could just switch the fab line over to 80C286 and ride the marketing wave created by so many other companies as long as it lasted.

I often hear that Harris just didn't understand what they should have done but have yet to hear a reasonable suggestion of what they would-could-should have done to successfully market the RTX instead of 286. I keep asking people and have yet to have a marketing expert give a good answer. Maybe there is one and I would like to know it if there is.

Best Wishes

...

...

The 80186 was indeed designed for embedded work, including some on-chip peripherals. I forget what about it made it awkward to use compares to Z-80 and 6809, but I remember feeling that way. Probably my lack of familiarity bordering on ignorance.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

--- mixed top and bottom posting fixed ---

Personally, I don't care one way or another how people post, I'm not interested in getting into the top/bottom posting wars. But mixed posting is even worse. I know you were trying to make a point, but it is of no value. People will do what they want to do no matter how many people them them to stop.

Besides, it is only a single key stroke to go to the bottom of a page. Is that really a big problem?

--

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

I don't think it was awkward compared to any of the 8 bitters. But it was not *PC* compatible because the IO map was different. I guess back then everyone either wanted a lower priced PC equivalent or they wanted more MIPs and the 186 did neither.

--

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

What newsreader? Sounds like a bug, or at least something that should have a switch to defeat it.

Are you guys kidding? It was that frickin' "segmented architecture" that was a pain in the ?##. I believe both the Z80 and 6809 were flat memory spaces, weren't they? Give me an 8085 any day of the 80's.

--RY

But it

--
%  Randy Yates                  % "My Shangri-la has gone away, fading like 
%% Fuquay-Varina, NC            %  the Beatles on 'Hey Jude'" 
%%% 919-577-9882                %  
%%%%            % 'Shangri-La', *A New World Record*, ELO
http://home.earthlink.net/~yatescr

...

Segmented architecture was a royal pain, but each segment was 64K, same as the 8 bitters. Segments were better than external hardware-supported banks. The galling part was that it didn't have to be that way.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

Well if you were happy with 64k, then the segmentation wasn't a problem: you could be in "tiny" mode all the time (which is how the CP/M converters worked, I believe.) The x86 had some more instructions and better addressing modes than either the 8085 or Z80. Probably not necessarily nicer than the 6809 though (but I only read about the latter: never got to actually play with one.)

Idle curiosity: why pick the 8085 over the Z80, in that time frame?

Cheers,

--
Andrew

Really? That's amazing. Why would they do that? Maybe you need to try a different reader. I'm using Outlook Express and directly off the Web when travelling with a browser.

--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Euredjian

To send private email:
0_0_0_0_@pacbell.net
where
"0_0_0_0_"  =  "martineu"

If there's a switch, I'd like to know it. Netscape 7.1 It has other bugs too.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯