The program reads data from the terminal using the SIK3 key. The protocol for this key bears a resemblance to the byte stream protocol {(p3,bytstream)}.

SIK3(limit ==> c,data;,,,SIK3) where limit < 4097.

c=0: "data" is line mode data, in the current character set.
A gray ball character in the data means, in line mode, that some data has been lost; in screen mode, that the screen has been lost and the user must reconstruct it.

Orange ball and black ball control codes {(cc)} may also appear.

c=1: A screen mode attention occurred. Data has the single byte AID.

SIK3(kt ==> x'19',(X'0102');,,,SIK3) Alleged type

SIK3(kt+1) Signal EOF

Transmissions

Line mode data consists of a sequence of items, either characters or control codes. {Control codes are one byte long. (cc)} The data transferred in each call from the producer to the consumer is called a (_packet). We consider the sequence to be broken up into a series of (_transmission)s, defined as follows. A transmission begins with the item following the previous transmission, or with the first item. A transmission ends with the first item that is in the activation set. Each transmission is divided into packets for transfer across the byte stream interface. Each packet is in just one transmission.

Within a transmission, data may or may not be delivered promptly. When a transmission is ended, all data in the transmission that has not already been delivered is delivered promptly.

A transmission is said to be in progress from the time the interface begins producing the first packet of the transmission until it delivers the last packet of the transmission. In other words a transmission is in progress except when the interface is consuming and the last packet sent was the last packet of a transmission.

A character is in the activation set if it is in mask set i and bit i of the activation set mask is on.

Example: To activate on carriage return and line feed, set the activation set mask to X'01'.

Mask bits are numbered from 0 through 7 starting with the high order bit.
i bit i mask set i.Irest=10;

0 X'80' all printing characters not in mask sets 1, 2 or 3, and space

1 X'40' upper and lower case alphabet and digits

2 X'20' percent sign, semicolon, and exclamation point

3 X'10' slash, equal sign, underscore, and circumflex

4 X'08' all control characters not in mask sets 5, 6 or 7, and DEL

5 X'04' backspace {control H}

6 X'02' horizontal tab {control I}

7 X'01' carriage return {control M} and line feed {control J}.Irest=0;

The activation set, and most other parameters relating to reading, cannot be changed while a transmission is in progress. The reason a packet never contains data from more than one transmission is to ensure that the consumer has an opportunity to change these parameters before the next transmission begins.

{nonref}Note that there are two possible reasons for including a character in the activation set.

The character may need to end a transmission because it signals the end of a string of data which the application program needs to process promptly {e.g., the carriage return at the end of a command}.

Or, the character may need to end a transmission because the program wants to change some of the parameters by which reading is taking place, for example the echo mask or activation set mask. The transmission must end so that the change can take effect at the desired point.

If you call SOK3 with output A, and when it returns, call SIK3 specifying echoing, A will be printed before the echoes.

This is called the non-buffering property because SIK3/SOK3 satisfy it if the module that supports SIK3/SOK3 does not buffer output and the SIK/SOK keys which that module relies on also have the property.