Collect Character restarts

Collect Character and Collect Next Character restarts
Function AddressDescription
RST_3 0018Collect character
RST_4 0020Collect Next character

RST 3 returns the character addressed by CHADD returning it if it's printable. If it is not printable then CHADD is incremented until a printable character is found.

RST 4 increments CHADD first before returning the next printable character.

These two resets are used in multiple places in the ROM, the BASIC tokenizer being one of them.

Last modified November 4, 2021: Add initial OS API calls (c7bd5ac)