80-Bus News


March–April 1984 · Volume 3 · Issue 2

Page 38 of 51

RUN – Programs may be run direct from disk by just entering RUN followed by the name of the program as stored in the disk directory. e.g. RUN"TEST" will load the program TEST from disk and proceed to run it.

TAB – As for ROM BASIC except that when additionally followed by two values will print characters specified by the second value until the print head reaches the column specified by the first value. e.g. PRINT TAB(20,46) assuming the cursor is placed on the first column of a line, will print twenty full stops.

WIDTH – Sets the width of the current output device when an automatic CRLF is generated. Set by default to 0 when no automatic CRLF is generated.

LOG – Followed by a suitable number returns the base 10 logarithm. The ROM BASIC LOG command returns the natural (base e) logarithm.

LN – Followed by a suitable number returns the natural logarithm!

And now the exclusive command set:

AUTO – Followed by up to two values. An automatic line numbering whilst entering programs facility. e.g. AUTO 100,5 will start auto numbering from line 100 in steps of 5. Default values are from line 10 in steps of 10. Unfortunately you can fool this command by editing another line whilst in the auto mode and then entering this new line. Although this line will be entered correctly the next line number automatically printed will have increased by the increment even though there has not been a line entered with the previously printed auto line number. The only way to revert to normality is to abort the auto mode by ESC and then issuing a new AUTO command. Absolutely essential to program writing though!

CALL – Followed by a suitable expression will call a machine code routine at the address specified. The routine should normally end with a RET instruction. e.g. CALL &C800 will call the machine code routine located at C800H.

DEL – Followed by two values will delete the XBASIC program lines between the lines specified. e.g. DEL100,200 will delete all lines from 100 to 200 inclusive.

DRIVE – The default drive in the disk version is the disk drive A (logical drive 0) and this may be altered with the DRIVE command. Any read or write commands after this will default to the drive specified unless specified otherwise in the command (see later disk commands). e.g. DRIVEB will now default to the second disk drive. DRIVET will now read and write data to and from tape when required.

ELSE IF ..... THEN ..... : ELSE – need anymore be said?

EVAL – I’m afraid the usefulness of this command escapes me. The command will evaluate text in a string expression. e.g. A$="1+X–EXP(X/3)":Y=EVAL(A$).

FMT – Requires a lot of words to explain its detailed use but suffice to say it is a PRINTUSING type of command which can specify the number of figures to

Page 38 of 51