![]() |
Routines |
Prev: 05615 | Up: Map |
Used by the routines at SAVE_ETC, SA_CONTRL, PO_SCR, CLS, CL_ALL, ED_EDIT, ED_UP, MAIN_EXEC, LIST, LPRINT, STR_ALTER, INPUT, str and read_in.
This subroutine is called with the A register holding a valid stream number - normally 253 to 3. Then depending on the stream data a particular channel will be made the current channel.
|
||||||||||
CHAN_OPEN | 05633 | ADD A,A | The value in the A register is doubled and then increased by 22. | |||||||
05634 | ADD A,22 | |||||||||
05636 | LD L,A | The result is moved to L. | ||||||||
05637 | LD H,92 | The address 23574 is the base address for stream 0. | ||||||||
05639 | LD E,(HL) | Fetch the first two bytes of the required stream's data. | ||||||||
05640 | INC HL | |||||||||
05641 | LD D,(HL) | |||||||||
05642 | LD A,D | Give an error if both bytes are zero; otherwise jump forward. | ||||||||
05643 | OR E | |||||||||
05644 | JR NZ,CHAN_OP_1 | |||||||||
This entry point is used by the routine at STR_ALTER.
Report O - Invalid stream.
|
||||||||||
REPORT_O | 05646 | RST 8 | Call the error handling routine. | |||||||
05647 | DEFB 23 | |||||||||
Using the stream data now find the base address of the channel information associated with that stream.
|
||||||||||
CHAN_OP_1 | 05648 | DEC DE | Reduce the stream data. | |||||||
05649 | LD HL,(23631) | The base address of the whole channel information area (CHANS). | ||||||||
05652 | ADD HL,DE | Form the required address in this area. | ||||||||
This routine continues into CHAN_FLAG.
|
Prev: 05615 | Up: Map |