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appears on the next screen line and the required program name is entered. The action of the command is identical to the READ NAMED Program FILE command, with the exception that the required program is NOT loaded into memory. The command is used to check that a program file may be successfully read from cassette tape.

Search For Tape Label – USR(2)

Read a cassette tape and search for a tape label as written by the SYS-EX “l” command. Display the first label found on the top line of the screen then terminate the commend.

The command may be used for positioning a tape prior to using the WRITE NAMED Program FILE command. The tape drive LED is switched on between entry of the command and command termination. If a tape label is not found, the command may be terminated by first stopping the cassette tape recorder and then typing four ESC (SHIFT:ENTER) characters. Four consecutive ESC characters read from the cassette tape recorder will have the sane effect.

Write Named Program File – USR(3) (CSAVE equivalent)

Write the BASIC program currently in memory to cassette tape. The program is preceded bye file label containing the specified program name, The file label will be recognised and displayed in full by the SYS-EX commands “q”, “r” and “v” in addition to the Write and verify named program file commands. The BASICs CLOAD and CLOAD? commands will also recognise the file label, but will use and display only the first character of the program name.

After entry of the USR(3) statement, the prompt

wName:

appears on the next screen line and the name of the program to be written is entered on that line. The tape drive LED is then switched on and, after a short delay, the file label followed by the file itself is sent to the serial output port for writing to tape. Finally, the tape drive LED is switched off.

NB.

It is possible to escape from the above commands while the file name prompt is displayed on the screen. (ie. rNamer:, vName: + wName:) To do this, backspace over the prompt or move the cursor to another line before pressing ENTER. An error message will be produced, but no harm will be done.

Returning To Sys-Ex From BASIC

It is useful to have an equivalent of the Monitor command which, instead of returning solely to NAS-SYS, returns to SYS-EX so that the full range of NAS-SYS and SYS-EX keyboard commands