OS_Wsq, Write to prefix sequence

Register parameters

RST 20H, DEFW $CE06

IN:    A = character
       HL = sequence buffer
OUT: 
       Fc=0 always
       A=0 if sequence completed, -1 otherwise

Registers affected after return:
     ..BCDE../IXIY same
     AF....HL/.... different

Notes

Internal operating system usage.

Write a char to the prefix sequence buffer.

Related calls

OS_Isq, initialise prefix sequence