Nascom News­let­ter

Insert a single specified byte at a specified memory location and move the original contents of that address and above, upwards in memory to make space for the insertion.

The section of memory delimited by: (i) address for insertion (ii) top limit for move minus two, is moved to the memory locations delimited by (i) address for insertion plus one, (ii) top limit for move minus one. The specified byte for insertion is then moved to the insertion address. The ‘top Limit for move’ parameter is the same an defined for the ‘e’ command.

AAAA – memory address at which the byte is to be inserted.
BBBB – top limit for move. Memory addresses from this address upwards are not accessed.
CC – hexadecimal representation of the byte to be inserted.

The command uses the Z80 block transfer instruction LDDR to shift the contents of memory upwards.

Alter the address of the NAS-SYS input table such that only keyboard input is permitted. That is, input from the serial input port is not accepted after entry of this command.