This is an earlier version of the facility described at (cswitchc). It has not been updated to cope with screen mode.

Switcher Proper

Operation from Terminal
The switcher manages a terminal and makes it appear as several virtual terminals or (_branch)es. (Its main tool is the terminal multiplexor module. {(tmmk)}) The terminal is in either (_user state) or (_control state).

In user state all characters typed by the terminal user except ESC are passed to the (_current branch) and all output from the current branch appears on the terminal. If the terminal is in line mode, typing ESC causes a change to control state. If the terminal is in screen mode, typing PA1 causes a change to control state.

In control state the following commands can be typed.

ESC - causes an ESC to be sent to the current branch and resumes user state. In other words, to send an ESC to the current branch, type two ESC's - one to enter control state and one to tell the switcher what to do.

<name>carriage return - makes the named branch the current branch and resumes user state.

carriage return - makes an active branch the current branch, prints its name, and resumes user state.

Whenever a branch becomes active a bell will be typed on the terminal. Active means the branch is trying to do output and can't because it is not current.

SWITCHER(0; ==> c,name;CCK3,SIK3,SOK3) {“Create branch”}
Creates a virtual terminal (“branch”) to be known by “name” which is an ASCII string of alphanumerics. c=0 if successful. This operation creates a Zapper Module (zmk) (so the branch can be disconnected later) and does what “connect branch” does. As usual, the character set is initially ASCII. The current implementation is poor on handling errors.

SWITCHER(1,name; ==> c;ZMK) “Disconnect branch”
“name” is the two character ASCII name of a branch. c=1 if there is no branch with the given name. c=2 if the named branch is the current branch. Otherwise, c=0 and the named branch is disconnected. The switcher end of the connection is destroyed and the user end is returned in the form of a ZMK key.

SWITCHER(2;ZMK ==> c,name;) “Connect branch“
c=1 if not enough space could be gotten. c=2 if ZMK does not obey the “reconnect” operation (zmk0). Otherwise c=0 and a new branch is created and connected to the ZMK key. “name” is a two character ASCII branch name.

There is currently no way to destroy a branch.

SWITCHER(kt;==>X'90D';)

SWITCHER_CREATOR(0;SB1,M,N ==> c;SWITCHER) {“Create switcher”}
N is a node or fetch key to a node containing:
Slot 0: SIK3

Slot 1: SOK3

Slot 2: CCK3

Slot 3: SB2

This operation creates a switcher and starts it operating on the terminal defined by SIK3, SOK3, and CCK3. SB1 must be a prompt official space bank; if not, c=1. SB2 is a space bank. M is a meter. c=0 if successful, 1 if SB1 is not a prompt official space bank, 2 if not enough space in SB1. If some other error occurs, in the current implementation, c=9 but the state of things may be screwed up.

SWITCHER_CREATOR(kt;==>c;) returns X'1090D' in c.