Nascom News­let­ter

Routine no. 81 Name: DTOHX

Convert an ASCII format decimal number (leading minus permissible), to a four digit hexadecimal value. Put the result into both NUMV in the NAS-SYS workspace and the HL register pair. Prior to calling the routine, the memory address of the first character of the decimal number (if negative, the minus sign) must be placed in ARG1 in the NAS-SYS workspace. Leading spaces are not permitted. If the decimal number is positive, the A and the C registers return with the value 00H. If the decimal number is negative, the A and the C registers return with the value FFH. NUMN in the NAS-SYS workspace is set to the number of numeric digits in the input decimal number. If the input value contains characters other than0 to 9 or if it is outside the range -32768 to 65535, conversion does not take place and the Carry flag is set ON. On a valid return, the Carry flag is set OFF.

Routine no. 82 Name: USCR1

Call a routine which starts 0400H (1K) beyond the start of SYS-EX. This routine is provided in order to allow user expansion of monitor facilities. The routine should only be called if the user has placed suitable code immediately following SYS-EX. HL, DE and BC are set to ARG1, ARG2 and ARG3 in the NAS-SYS workspace, respectively. The A register is set to 82H.

Routine no. 83 Name: USCR2

Identical to USCR1 except that the A register is set to 83H.

Well, that’s it for this issue. In the next magazine, the finishing details of the monitor extension will appear. Also, the full hex dump of the monitor extension will be printed so that you can finally try out all of the SYS-EX facilities.