REVIEW OF EXTENSION BASIC by LEVEL 9 COMPUTING
by David J. Plews
(Ed.’s Note – As our printer currently has no ‘at’ sign, for ‘‰’ read ‘at’.)
WHAT YOU GET :
One TDK D C46 cassette with Extended BASIC (hereinafter XBASIC) and relocator
program and a basic demonstration program (side 1 has copies at 1200 baud, side 2 at
300 baud), one 28 page manual.
WHAT YOU NEED :
A NASCOM 1, 2 or 3 running under NAS SYS 1 or 3 with the ROM BASIC and a
minimum of 16K of RAM.
The 1200 baud version loaded error free first time.
RELOCATING IT :
The loaded program was a full 8K. This consisted of 4K for the XBASIC program
itself, a couple of hundred bytes for a relocator program and the rest was an
advertising and copyright message!! To relocate the XBASIC into memory the program is
executed at 1000 HEX. There then follows an advertisement and a prompt asking you
where you would like XBASIC to sit in memory by entering the start address of a 4K
block. I have 32K of RAM so it’s 8000 HEX. There is a delay of less than 1 second
while XBASIC is relocated and control is then returned to the monitor. The relocated
version can then be stored on tape. There then follows a tedious rigmarole of starting
XBASIC up to work with ROM BASIC. The ROM BASIC is cold started and the top of user
RAM is set by the ‘Memory size ?’ prompt so that XBASIC is not overwritten. The
appendicies help out here, for 32K RAM it’s 32679. After entering this you then have
to re-enter the monitor and initialise XBASIC by executing it at its start address,
i.e. for me E8000. After another short commercial control is again returned to the
monitor. BASIC is then warm started with a Z, and away you go!! If you have to go into
monitor at any time subsequently, to return to the full 12K basic system warm start
with a Z and then enter SET. You get another commercial and you’re off. If you get
mixed up and forget whether you’re running under XBASIC , SET– will check for you.
So what do you actually get in the 4K program? Well XBASIC gives you 32 (yes
32 !!) extra commands running under ROM BASIC, and you can add your own !! The new
Now to describe them all if the editor will let me!!
AUTO – Automatically generates line numbers after each ENTER. You set the starting
number and subsequent increment. Needs no further comment.
CHECK – This looks through a program to see if there are any calls to unreferenced
DELETE – This deletes lines in a program. The two arguments needed are inclusive.
EDIT – This command is a real gem!!! On entering the EDIT mode you can write a single
program line which can fill the entire screen, i.e. over 700 characters!!! The
demonstration program has a few examples in it. These long lines can be edited as
normal while in the EDITmode. O.k. a line 700 characters long with multiple statements
isn’t exactly elegant but it IS exceedingly useful. (Also see WRAP.)