however, if you want to have a max232 to program an 8051 family uC, then go for ds87c420/430/440/450. the process if fully discussed in the ultra-high-speed micrcontroller user guide in maxim/dallas website. they also offer a freely downloadable software called mtk2
Syrax, hold on !
Do you want more headache than you have now.
I know you have a laptop with no parallel port and that's the reason for which you look to program AT89S52 through serial port (obsolete too for laptops), but keeping ISP features.
So you choose one programmer that needs a master pre-programmed AT89S52 chip which acts like a gateway between laptop serial port and your new AT89S52 that must be programmed through ISP interface. You have now problems programming the master through your friend's PC parallel port (with 74HCT541 buffer or not).
Imagine now what problems you'll have finding a programmer for the master AT89C2051 used in the circuit mentioned above by gamegurus. Even if you have the hex file for AT89C2051 how are you expecting to download it ?
OK, you have a USB to COM adapter. I know, you want to build a programmer attached to a laptop with well common USB port and legacy serial COM and/or parallel port.
Now tell me if my suppositions are wrong.
You have a laptop with USB. Then a USB to serial adapter (COM). Then a programming board with serial data input and a DIP40 socket for AT89S52 like this one: **broken link removed**
The question is : Have you the programming software for the programming board ? Because ProLoad V4.1 by Sunrom Technologies won't work with your USB to COM adapter.
i don't know that / proload doesn't work with USB to Com adapter/ i can try use easy downloader.
Or can some tellme what kind of programmer i can make trough USB
THANKS
how can i download hex file to at89s52 target board through my laptop? lap does't have a port to connect db25.. so which circuit ei have to refer now.. thanx in advance..