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eltonjohn
Joined: 22 Feb 2002
Posts: 1558
Helped: 22
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 08 Sep 2004 19:11 Real TIME Java SimpleRTJ and Others virtual machines |
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I've been playing with SimpleRtj http://www.rtjcom.com/home.html
this is kind a nice concept .. The deal is to prelink java applications (classes) then they are downloaded to be executed much faster by the java machine . Has anybody used this concept .. I just did a port of the java machine to a 51 using keil . I'm trying to see how can i use the banking model with several java programs ..! I'm not a Java guru . i'm learning it from its C sources as i go along! (weird hein?)
The philosophy of java is "PORTABILITY" write once run many
it means that a program should be able to run on a PC and on Cellphone
from that respect this is interesting .But to really make it happen a lot needs to be done ..
But MAYBE we can start a JAVA discution group right here!
Last edited by eltonjohn on 09 Sep 2004 18:56; edited 3 times in total |
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eltonjohn
Joined: 22 Feb 2002
Posts: 1558
Helped: 22
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| 09 Sep 2004 5:35 Re: Real TIME Java "SimpleRTJ" |
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| Well guys i don't give a damm about winning some points .. The thing is that it seems than in our neighborhood nobody is interested in java for embedded applications .. there is a lot to discuss . a lot to advice .Java is a great approach to embedding applications ..is anybody out there willing to talk about it???
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geconom
Joined: 12 Feb 2002
Posts: 295
Helped: 3
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| 09 Sep 2004 6:00 Re: Real TIME Java "SimpleRTJ" |
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I am interested in Java for embedded systems. As the link you provided says, Java can take the role of the RTOS so, instead of having:
uC+RTOS+Application=Embedded System
you may have:
uC+JVM+Java Application=Embedded System
At the moment I am interested in another combination, utilizing specific uCs equipped with JVM in hardware, like Sun's picoJava II which has Java as its machine code. At the moment I am trying to investigate the following target architecture:
Java uC+Java Application=Embedded System
I will keep in touch!
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eltonjohn
Joined: 22 Feb 2002
Posts: 1558
Helped: 22
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| 09 Sep 2004 18:31 Re: Real TIME Java "SimpleRTJ" |
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Now there is JOP at http://www.jopdesign.com/index.jsp a real time java Processor that can be implemented on a FPGA ( sources can be downloaded from there too ,there is even a TCP/IP stack)
On that website you will find several very nice papers on how to implement java on a realtime processor
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schoeberl
Joined: 09 Sep 2004
Posts: 1
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| 09 Sep 2004 22:38 Re: Real TIME Java SimpleRTJ and Others virtual machines |
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I could help or answer questions on this Java RT stuff (on JOP) as I developed JOP 
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eltonjohn
Joined: 22 Feb 2002
Posts: 1558
Helped: 22
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| 10 Sep 2004 1:16 Re: Real TIME Java SimpleRTJ and Others virtual machines |
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Wow!!!! Mr Shoeberl HIMSELF .. what a nice surprise !.. what a nice place this is .. Well for the moment i downloaded all your 10 papers . and i will spend the whole weekend reading them .. I think that you did a great job
This is a great surprise ..
CONGRATULATIONS for 5 years of NICE WORK DONE !
Keep it up ..!
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fireplus
Joined: 31 Oct 2003
Posts: 195
Helped: 5
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| 20 Sep 2004 6:37 Re: Real TIME Java SimpleRTJ and Others virtual machines |
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DEAR eltonjohn,
how are you ? 
could you please share with us how to port the java machine to a 51 using ke*il .
thank you anyway
Fire in the Wire :sm2:
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eltonjohn
Joined: 22 Feb 2002
Posts: 1558
Helped: 22
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| 23 Sep 2004 19:56 Is JAVA REALLY WORTHY to go trough that PAIN? |
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Is JAVA REALLY WORTHY to go trough that PAIN?
People that advocate Java for embedded applications often mention the BENEFITS ALOUD .. security , no need for OS .. Garbage collector ( if you implement it and PORTABILITY ) ..
Well the portability is NOT that simple .Anyways this same people never mention the AWFUL slow PERFPRMANCE of java VIRTUAL MACHINES .. it can be as SLOW as 20 times less than NATIVE code .. I would like to see more discutions on the TRADEOFF of these techniques .. I'was implemnting a Java VIRTUAL machine on a 51 CPU .. running at 50Mhz to a 100Mhz .. But the java machine takes a big chunk of espace and being 20 fold times slower my 100 Mhz Cpu becomes a 5 Mhz machine .. BRAVO! What do i get ? IN RETURN .. a CROWDED chip!!! So i told myself ..THE HELL with all that and i ended up putting a BASIC interpreter like the BYWATER.. So my question is Why go trrough ALL that pain of CONVERTING to BYTECODES .. Don't give me that bull of PORTABILITY .. all javamachines don't implement the same classes anyway ..and more stuff is being added all the TIME .. Now SUN is implementing new bycodes with INTERRUPTS .. boy SLOWER and SLOWER ..
Maybe is time to go back to C and good all OS .. That really works !
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czpir
Joined: 18 Apr 2002
Posts: 63
Helped: 1
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| 27 Sep 2004 8:48 Re: Real TIME Java SimpleRTJ and Others virtual machines |
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Elton
I would need to actually try out some code before giving you some reasons as to why Java should be used.
I would appreciate it if you could throw some light on the methods that you used to load the class file (.bin) into the 8051 RAM or ROM.
-CZ
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