80-Bus News

be printed in front of and behind a decimal point.

HOLD – A real beaut. this one – especially when used with the CHAIN command. HOLD followed by up to two line numbers will hold a range of lines for view in a program so that another program may be appended to it or so that this range only may be renumbered and thus moved to another part of the program. The effect is that the rest of the program seems to have disappeared. In fact it is still resident in memory but cannot be found with a LIST command nor executed with a RUN command. The listable area can be modified however and even RUN without affecting the hidden areas. Loading another program removes the listable area and also the upper hidden area if there is one but does not destroy the lower hidden area. e.g. HOLD100,199 leaves lines 100 to 199 in view and a command such as a renumbering command will only renumber that which is in view.

MGE – Restores sanity to a held program.

HEX$ – Followed by up to two values returns the hexadecimal string corresponding to the first value as a string of characters whose length is dependant upon the second value (4 assumed if not specified). e.g. HEX$(1234) returns the string 04D2. HEX$(100,2) returns the string 64.

INCH – Returns the ASCII value of the next input character which it waits for. e.g A=INCH places the ASCII code of the next key pressed into the variable A

INCH$ – Returns the next key pressed as for INCH above but as a one character string. e.g AS=INCH$. Also useful in conjunction with tape or disk files when certain characters may cause undesired effects under an input condition. See later commands on file handling.

KBD – Similar to INCH but scans keyboard and does not wait for a character.

KBD$ – As for INCH$ but does not wait for input.

RENUM – Renumbers a held program or the whole of it if a HOLD has not been previously issued. Used in conjunction with HOLD and MGE it is a very versatile command.

IOM – Followed by two values. This command alters the bits in the IOMOD word in the workspace which consists of sixteen one bit flags of which seven are used at present in XBASIC. By setting the bits to 0 or 1 the operation of certain areas can be modified. These require more explanation than is possible here but it is with this command that one prevents the switch from Screen Edit mode to Line Edit mode during a program run or disable the use of the break key etc.

MOD – An operator which is the remainder from a division. It can be defined as follows: A MOD B=A – B * INT(A/B). e.g 5 MOD 3 returns 2.

MUL$ – Followed by a string and a number returns the string repeated a number of times dependant upon the number. e.g. MULS("*",5) returns the string *****.

PI – Returns the value 3.14159. Very useful with the AVC and is faster than using a variable to hold the number for pi. This function actually uses 3.141593 but is only printed to five decimal places.