CAN I USE 8051 TO CONNECT A PC MONITOR

Yes I know, 8051 is simply a microcontroller.Here I am using ethernet hub to connect a second monitor. Presently I have a graphics card, so I can use a second monitor without any complication. But I plan to make hardware which can connect a second monitor without a graphics card. So my plan is to connect a monitor using an ethernet HUB. So I am thinking about a hardware which can serve this purpose.

So I am thinking about a hardware which can serve this purpose.

So don't think 8051.

First off, to generate the timing - and scan through the image memory 60-100 times/second - you need a VGA chip. I repeat: You need a VGA chip. If the VGA chip doesn't have the graphics memory built-in, you will need external memory. Either twice as fast as the requirement for the normal output, or two-port, to allow a processor to access the memory without affecting the image output. Then you either need a processor to draw in the graphics RAM, or an ethernet-to-RAM chip that will allow your PC to send ethernet commands that gets converted into either raw memory writes or into draw commands for the microprocessor.

Then you need a graphics driver for the PC. If the PC is running Windows, it will take quite a lot of work to create the graphics driver.

That is quite complicated, just to create a cloned display.

The next alternative is of course to NOT use ethernet to transfer the data, but to settle for ethernet cables to send the video signal. In that case you can skip a microcontroller and buy video buffer/splitter/repeater chips. Just use a high-impedive video buffer to split off a copy of the video signal sent to a normal VGA monitor and send that video signal on the ethernet cable. Pick up the signal in the other end and buffer it once more before emitting it on a VGA connector. You will get bandwidth loss and can't use the highest refresh speeds or resolutions, but you will get an image. Of course, this kind of equipment are sold by a lot of companies and is often used together with KVM switches to have a console a long way from the computers. The only need for a microcontroller in such a solution is if you also want to send the mouse/keyboard data over the ethernet cable, or to listen for HS/VS and perform some automatic action when the video signal is detected. But no controller is needed for just transmitting a video signal to a monitor far away as long as you don't digitize the signal and either compress it or sends it in frames with error correction and/or retransmission.

The third alternative is to look into buffering of DVI signals, to control a digital TTL monitor remotely. The problem here is that the frequencies are very high and can only stand a very limited amount of jitter and other timing errors between the individual signals. It is the timing requirements that is the big reason why more and more high-speed data is sent serially. But the concept is similar to buffering an analog video signal and conditioning/repeating it.

But if you do know how to build such equipment, you would not ask questions on this forum. You would just google for suitable components and then build a video repeater.