gSim51 - An open source 8051 simulator!!

Welcome to the Home Page of 'gSim51'

Latest news!! gSim51 mailing lists are up now!!

Click here to go to the gSim51-devel page!!

Click here to go to the gSim51-users page!!

Click here to go to the gSim51-news page!!

Please do join these mailing lists!! gSim51 needs users!!

What is gSim51?

gSim51 is an open source,easy to use, text based simulator for the 8051 microcontroller running on the Linux Platform.It has been designed to match the DOS 'Debug' program so that those who are already acquainted with 'Debug' can easily learn using gSim51 within a very short time. Following the unix tradition of simplicity and efficiency, all the commands of gSim51 are short and may seem difficult to remember at first. But in the end these short, terse commands prove to be very efficient in doing the job of simulating your code.

What are the salient features of gSim51?
The following is a list of the salient features of gSim51:

gSim51 incorporates full 64k code and 64k data in addition to the on-chip 4k ROM support for all your programs. Thus, instructions like MOVX and MOVC are supported by gSim51.

Not even a single instruction has been left out of the instruction set of the 8051 microcontroller, which means that gSim51 can simulate all the 255 instructions of the 8051.

gSim51 has a novel debugging feature. it can take a Snapshot of the entire 8051 system memory at any point of time during simulation and store it in a human readable file. Later gSim51 can download this snapshot file into the 8051 system memory to restore the state of the simulator when the snapsot was taken.This feature is greatly helpful when some bug lies deep within the code space, as one need not run the simulator upto that point repeatedly. Only once during the first simulation a snapshot is taken just before the probable location of the bug and later that snapshot can be loaded to bring the simulator to the same state that was at the time taking the snapshot.

gSim51 is fully Intel Hex file compatible. So you can now use any assembler of your choice to generate the equivalent hex file and run it in gSim51.

The simulator can be made to run in its 'Console' mode, wherein it behaves almost like a microcontroller kit where you can directly punch in the preassembled hex code of your program.

gSim51 incorporates full debugging facilities like setting,removing breakpoints as well as 'step into' and 'step over' features. In this regard, therefore, gSim51 can also be thought of as an efficient debugger.

Almost all of gSim51's commands resemble that of DOS debug, hence use by 'debug' users is facilitated greatly.

The commands of gSim51 provide great flexibility during simulation. For example the 'r' command without any parameters shows all 8051 registers. However, the same 'r' command when followed by any register name enables editing of that register. Same goes for other commands as well.

gSim51 has provisions for simulating 8051 interrupts during execution, which is another valuable asset.

A short, but comprehensible online command reference is always at your disposal for refering to any command during simulation. Beginners are advised to go through the offline documentation and also the short tutorial, before trying out the simulator. A few test programs in Hex format are given to try out the tutorial.

Who is the author of gSim51 and how can I contact him for reporting bugs and further information?
you can contact me at my email address which is: cmantadutta@yahoo.com. My PGP public key is accessible at this location. You can also get my public key from the MIT key server by querying for 'Seemanta Dutta'. But be careful, DON'T USE ANY REVOKED KEYS FROM THERE. Currently use the key with user ID 0x0804719D only. You can also write to me at the following address:

Seemanta Dutta
C/o A. Chowdhury
Opp. Anuradha Cinema
P.O. Bamunimaidam, Guwahati
Assam, Pin- 781021
INDIA

Who are you and why are you doing this?
I am Seemanta Dutta, a Graduate in Electronics and Communication Engineering. I have a very passionate interest in programming languages, especially C and assembly. I am also a very enthusiastic and die-hard user of linux. I am doing this because I fully endorse the Free Software/GNU movement and would like to contribute towards its development in whatever way I can.If all the programmers of the world unite, we can very easily fight this menace of proprietary software.My other love is the world of microprocessors and microcontrollers to which I am eternally attracted. My area of interest is therefore in designing and creating embedded systems that can help solving real life problems and make our lives comfortable.

I began work in this simulator when my project In-charge at IIT Guwahati gave me an assignment to make a simulator for the 8051 microcontroller. At the time when i came up with the first working version of my simulator, it was very limited in operation. Firstly, it was called 'Sim51' and not 'gSim51' as it is now and it ran only under the DOS enviromment. Secondly, it had only about 110 instructions' support in it without full 64k data and 64k code support.All it supported was 4k of on chip ROM. A lot of things have changed since then. Now I have ported my earlier simulator and christened it 'gSim51' which has complete set of 255 supported instructions along with full 64k data and code support. gSim51 also supports extended debugging and a feature of snapshots. It now also supports interrupts which are an integral part of any microcontroller based system.

Where can I download gSim51?
You can download gSim51 by clicking here or by pointing your browser to http://gsim51.sourceforge.net/cgi-bin/redirect.pl
You can also browse the CVS repository of gSim51 by follwing the link for the same from the above page.
Please note that every download of gsim51 is counted for statistical reasons. If you wish you can also enter additional information as an user of this software by clicking here