Có bác nào biết về Stop-and-Wait k0?????

[ohaio80]

Tôi có bài tập môn Information Networking như sau:
Explain how stop-and-wait flow control works when a printer receives information from computer?
Tôi không hiểu câu hỏi cho lắm, bác nào biết thì giúp tôi với
Thanks

[ohaio80]

Chán quá, chả bac nào biết về vấn đề này cả nhỉ, thôi tự mò lấy vậy

[hanoi_girl]

That is a kind of flow chart of how printer receives and requests for information from computer. On this post of the forum, I will explain very brieftly how printer "processes" the infromation though parallel I/O port only.

First you need to understand the paralell I/O operations that includes port reads and writes as well as strobe and handshake on designated ports of IC of that printer's PCB. Secondly, you need to understand all the registers and control bits concerned with the discussion of parallel I/O ports - port A, Port B, Port C....PIOC (depends on the architecture of the IC on that MB). Each port associates with a hex address. For example, address $1000 is for Port A, address $100E for port D and so on. And each port has control bits from bit 0, bit 1, bit 2 and etc... Each bit has it own function Strob, Invb, Hnds .....

In your question - generally - you have a flow chart of how printer works and your lecturer asked you to explain it. The flow chart normally starts with (begin) -> Read in Data Port->examine port (control bits)->if Data presents->Set Flag bit to 1-> Sends Ack(acknowledgement) to computer telling it to Stop sendind data ->Write date out. Pull Flag bit to 0->send a handshake to tell computer that it is ready and wait for data. If data not present ->Loop back to strobe (waiting) stage.


Hope that will help you.

[ohaio80]

Cám ơn bạn Hà nội Girl nhìu nhìu :p