TYPEWRITER
The Typewriter will operate in the input mode or the output mode.
For each In-Out Transfer instruction one character is typed. The character is specified by the right six bits of the In-Out Register.
Input Mode
tyi iot 4
This operation is completely asynchronous and is therefore handled differently than any of the preceding in-out operations.
When a Typewriter key is struck, Program Flag Number One is set. At the same time the code for the struck key is presented to gates connected to the right six bits of the In-Out Register. This information will remain at the gate for a relatively long time by virtue of the slow mechanical action. A program designed to accept typed-in data would periodically check the status of Program Flag One. If at any time Program Flag One is found to be set, an In-Out Transfer instruction with address four must be executed for information to be transferred. This In-Out Transfer normally should not use the optional in-out halt. The information contained in the Typewriter's coder is then read into the right six bits of the In-Out Register.