Thanks Darrel,
I have down loaded all the files associated with instant interrupts. It will take me a few days to learn them and use it in my projects.

Hi SteveB,
Thanks for your reply.

"And since each PIC BASIC Pro commands are made up of many ASM commands, there could be quite a large delay (especially if you had something like PAUSE 5000). The advantage though is that you can write your ISR entirely in PIC BASIC Pro, and don't have to worry about what's going on under the hood. But, if you can't afford any delays in your interrupts, you need to work the interrupts in ASM. Or use Darrel's Instant Interrupts."

I know that PBP commands are non re-entrant, but that is not the case with Bascom. What happens in bascom is the waitms can be interrupted and the only draw back is that the duration of the wait gets extended.
You have a free demo version Bascom in which you can write upto 2k. You also have an extensive user manual, which will get you started immediately. Just have a try. To get started in timers, counters and interrupts in basic it is the easiest. Hmmm... can't say until i have worked with Darrel's instant interrupts.

I will be working on a 50 hz line-interactive UPS design using a micro controller. The heart of the program will be to generate two 50hz out of Phase pulses whose duty cycle depends on a feed back from the output voltage of the UPS. I intend to use two timers for it. Timer0 to generate a constant 10ms(not exactly 10ms but say 9.5ms or so providing a dead band of 1ms between two pulses) and timer1 to measure time until my A/d value of the feed back(from the output transformer) reaches a preset value(which translates to 230v output).
There are 2 transistor banks. You first switch on one bank and check the a/d value. If the a/d value reaches the preset value, stop timer1 and switch of that bank. Now switch on the other bank exactly for the the same timer1 value. Each of the bank will be switched on only for the timer1 duration.If the banks are switched on for unequal time value, then there will be what we call a flux imbalance in the transformer core we switch onto. This would lead to huge amount of current drawn onto one bank of transistors and resulting in their failure. During the dead band period i have to make other measurements like battery voltage, mains incoming voltage etc.and control a few relays, leds and buzzer for incoming mains voltage regulation and annunciations.
There is already a thread on powersupply/ inverter in this forum.

Since i was interested in this project, i just thought it right to tell you because this is a project whic will have to use many of the hardware featue of the PIC.
Let me figure out a way to write the code with Darel's instant interrupts.

Thanks Guys, for your response.
Raghunathan