1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Yapp-protocols extension (Appendix 19)</title>
</head>
<body background="/back_fbb.jpg">
<p> </p>
<h1 align="Center"> Extensions to YAPP-protocol<small>.</small> </h1>
<p align="Center"> (Appendix 19) </p>
<p> </p>
<pre> These extensions are used in TPK 1.65a (and up) and FBB 5.14 and up.<br><br>HEADER extension.<br><br> The header now carries the DATE and TIME of the file being transmitted.<br>[SOH] [Len] [Filename] [NUL] [File Size] [NUL] [Date] [Time] [NUL]<br><br> The Date and Time are the values reported by DOS, coded in 4 hexadecimal<br>digits and are sent in ASCII (8 characters).<br><br> The receiver has the choice of using either extended Yapp with checksum or<br>normal Yapp.<br><br> The normal Yapp reply is RF, as before and the receiver can keep the date<br>and time information .<br><br> The extended Yapp reply is : RT Receive_TPK and is coded : [ACK] [ACK]<br><br> If the receiver reply is RT the protocol used will be what I have called<br>YappC for Yapp with checksum. When the sender gets this packet he MUST use<br>YappC.<br><br>Data Packets extension.<br><br> If the receivers reply is RT the protocol used will be YappC. The checksum<br>allows detection of packets corrupted along the link, particularly on the<br>RS232 lines where there is no error control or correction (or it's very<br>poor!)<br><br>Data packets : [STX] [Len] [Data] [Checksum]<br><br> Checksum is the sum of all data bytes anded with FF in 8 bits like Xmodem.<br><br> If the checksum is bad then the receiver must send a Cancel and enters CW<br>state.<br><br>Crash Recovery.<br><br> A new field has been added to the resume reply to tell the sender if the<br>receiver can use YappC or not. Resume is sent instead of RF (or RT).<br><br> Resume reply for Yapp: (as used before by TPK and FBB)<br><br> [NAK] [Len] [R] [NUL] [Received Length] [NUL]<br> I I I<br> I I +-- in ASCII as in the header<br> I +-- as Resume !<br> I<br> +------- len of the following bytes<br><br>Resume reply for YappC:<br><br> [NAK] [Len] [R] [NUL] [Received Length] [NUL] [C] [NUL]<br> I<br> Tells sender I can use YappC -----+<br><br> When the sender gets this packet then he must also use YappC.<br><br><br><br>
<font color="#800000">This page was last updated 17-Apr-99</font>
</pre>
</body>
</html>
|
