Keil Tiny RX?

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Is anyone here using RTOS from Keil?

Does it make job much easier?

What are it's advantages and dissadvantages?

Thanx, Mickey.

Re: Keil Tiny RX?

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I have used a few different RTOS from different vendors, and written a
few myself, but I haven't used that one.

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What job is that?

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There are two very different issues here.

1.  Whether or not your project requires an RTOS at all or not.  I
have done quite a few projects with 8051 family controllers and never
needed one.  Originally it was not too likely that many applications
that needed an RTOS could even fit well on an 8051, but newer
derivatives are faster and have larger memory spaces, so it is

2.  If your project could benefit from an RTOS, exactly what RTOS
would be best depends a great deal on your application and its

Below is copy of a reply to another post I made here in
comp.arch.embedded to another poster's question about use of an RTOS
in embedded systems.  I still feel that it is a very satisfactory
answer.  At least one small company that produces an RTOS for several
embedded processors thought it was satisfactory also -- they asked me
for permission to quote it on their web site, which I gave.

To answer the question of when there is a need for an RTOS, the answer
is almost never, at least in the sense that something that is possible
with one would be literally possible without one.

As to when it might be a very good idea to use an RTOS, that's a
little different.  In my experience it becomes a good idea to consider
using an RTOS when the requirements for a system include a large
number of asynchronous events, multiple priority levels, and a
significant percentage of processor loading.

There are many different RTOS, commercial, freeware, and open source,
that can be used on different processors, but that is mostly practical
for 16-bit and up processors.

As to a good place to read about, and ask questions about, RTOS issues
is news:comp.realtime.  Look for their FAQ, there is a large amount of

The full thread may be found at the following link:

Jack Klein
Home: http://JK-Technology.Com
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Re: Keil Tiny RX?
I looked into their Tiny RTOS some years ago.  When it switches contexts it
swaps out all 256 bytes of on-board RAM, which made it too slow for our
purposes.  That was for a "basic" 8051, it may do better with some of the
newer and faster 8051 derivatives.

Do you really need a full-featured RTOS?  We found that the best move for us
was to roll our own - a simple round-robin task switcher that was quite
effective for our moderate-complexity application.

Mark Ainsworth

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Re: Keil Tiny RX?
Hi, Mark.

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What was the reason you considered that RTOS in the first place?

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I think they have worked it out allready. They should have in few years.

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Why did you make your own RTOS, was it too complex to handle all the things
without RTOS?

Re: Keil Tiny RX?

I have also done quite a few things without RTOS I just wanted to find
out is it worth to learn for example Keil RTOS, and does it make
development much faster and does it take too much resources and
so on.

Thanks for comments anyways.

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I ment to comment this question of yours above but I realised it is in
place, I spoke of "job" as generally a medium sized project (device),
like using keys, LCD, EEPROM, AD and so ...

Re: Keil Tiny RX?

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IMO, the major factors are whether you need to doing more than one thing
"simultaneously" (multi-tasking), and whether the various tasks have
complicated states, which would make round-robin processing messy.


Re: Keil Tiny RX?

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I have not used Tiny, but I can say the FULL version of RTX51 works
extremely well, even on a plain 8051 at 11.059MHZ.. quite efficient, even
with banking support for my application. Your application may or may not
need an RTOS.. as always, it's the application that determines the resources
and OS ( if any )..

Re: Keil Tiny RX?
Another small RTOS to check out is Sciopta (
It's good for 8/16/32 bit - based on assembler and c (source code included)
and it's royalty free.....

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Re: Keil Tiny RX?
So can anyone say when RTOS would be necessery
it seems to me that for 8051 complexity of projects
it is almost never needed?

What kind of applications would "need" RTOS?

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