HOW TO SEND FILE/TEXT FROM PC TO ZX EQUIPPED WITH ESP-01
*********************************************************

1)INTRO
This is an outline on how to transfer files/texts (further f/t) from PC to ZX Spectrum with ESP-01 wifi module.

2)PC side
The transfer is done via HTTP method POST with a form. So EVERY higher computer (PC, Apple, mobile phone) can use it with a WEB BROWSER.

The form will contain some fields for user to enter:
- Your name (optional)
- Your message to the receiver (optional)
- File select (compulsory)
- the form sends length of file too
- with the text it will be something alike
- send button

3)ZX side

First, perhaps, in case ZX is a sender, it should test the receiver's server by:

-AT+PING="192.168.0.104"
The answer is either OK if the pinged server is up, or ERROR if not.


If ZX is a receiverm then:

The ESP-01 module needs to run a server which will accept the data from PC form.
- AT+CIPMUX=1 (needs for server run)
- AT+CIPSERVER=1,10001 (optional port) (ESP01 IP need to be set in HTTP send form including port number, eg.10001)


Now, a server is running on ESP01 and is listening, once HTTP form selects a file and click on SEND button, the server on ZX starts to accept data. The HTTP form sends a lot of useless data, but what ZX will be interested in is:
- REAL_FILE_SIZE
- FILENAME with incoming data after Conten-Type: text/plain
- user name (optional)
- message to receiver (optional)

The ZX software can also display an IP address of the sender, which can be read from the answer of AT+CIPSTATUS command, together with port number.


Upon having received the file, ZX should write an answer to the sending server, so that it can close and display the user positive feedback. ZX does not have to bother about PC server IP, ESP module has opned the link already. ZX should send something like:

- AT+CIPSEND=0,90
> HTTP/1.1 200 OK	(code is in fact irrelevant)
Content-Type: text/html;
Content=Length: 19

<p>File uploaded successfully</p>
<button onclick="history.back()">Go Back</button>

And also button to jump back should be added in ZX answer to PC server(I have not tested it yet).

In case ZX refuses the file, it can just send similar message with something like <p>File refused by the user</p> and then close the connection.
