Micro­power

you would only need to enter the subroutine once, making the necessary adjustments to the subroutine call instructions.

The command is entered as Faaaa xx yy zz . . ., where aaaa is the start address for the search, and xx, yy, zz . . ., where aaaa is the start address for the search, and xx, yy, zz, . . . is the string of bytes (up to 9 bytes long). However, the above program was written for use with Nas-Sys 1; when used with Nas-Sys 3 strings of three or more bytes can have strange effects on the tabulate command, because the extra arguments affect the formatting of the display. The routine is relocatable, that is, it may be used at any memory locations. The start address should be stored at £0792 for NAs-Sys 1; if you must use it with Nas-Sys 3, the appropriate location is £078C.

Generate Gxxxx yyyy zzzz

The command produces a tape copy of a program between addresses xxxx and yyyy, which loads automatically and then self executes at address zzzz. The G routine first resets the output table to send data to both the CRT and the serial port., and outputs the following characters: Newline, E, 0, Newline, R, Newline. A delay is inserted between each character. It then calls the write routine to send data from xxxx to yyyy to the tape. Finally, it outputs and E, the start address, zzzz, and a Newline. A tape produced by the Generate routine is played directly into the machine with the monitor in the INLIN loop. Because this loop scans both the keyboard and the serial input the data received is treated as if it had been entered from the keyboard. Thus the first Newline sets the cursor to the beginning of a line, E0/​Newline resets the monitor, and R/Newline, executes the read command. The machine then reads in the data stored by the write command, and finally Ezzzz/​Newline starts the program at address zzzz.

The G command suffers from two drawbacks; firstly, the tape LED is not turned on until the Write or Read commands are invoked, which makes it inconvenient in systems which use the tape LED to control the tape recorder motor; secondly, if the program is loaded incorrectly the command still goes ahead and runs it, which can have unfortunate results.

Half Duplex Terminal H

When the H command is executed, the monitor is put in a loop in which the INLIN routine is continually scanned. However, when a Newline is received and the INLIN routine is left the input line is not dissected by the PARSE routine, but INLIN is recalled. Consequently commands are not accepted, and the only way to escape from this command is to press RESET. If your Nascom is connected to a printer, this command will enable you to use the system as a typewriter, suppressing the machines normal response to valid commands and error messages on invalid input. Of course, any commands that you need to give, such as Kn to set the keyboard options, U to activate the printer routine, or Xn to control external input /output, will have to be entered before the H command.