80-Bus News

  

April–June 1982, Volume 1, Issue 2











Page 47 of 55











47

PRINT% – This commences a print at the specified point and has been included, so the manual says, for easier conversion Of TRS 80 programs to NASCOM’s. Without the ‘%’

PRINT acts as normal.

PUT – Arguments which are numbers are printed as their equivalent ASCII characters and strings are printed as messages.

’ ‘

WRAP – This is yet another gem!! When enabled by a + it prevents word wrap round i.e. stops a word being printed half at the end of one line and the other half at the beginning of the next. In conjunction with the EDIT command it makes text handling a real doddle!! To disable it the argument is ‘-’.

VDU – This prints strings and evaluates string expressions and prints them at the coordinates specified as per ordinary SCREEN coordinates. The top line can be written

toe IF..THEN..ELSE – Speaks for itself. REPEAT..UNTIL – Loop until condition is true.

WHILE..WEND – If the condition is true then loop. These commands give truely structured programming in BASIC, and they are VERY easy to use. You don’t need to know

Pascal!! BREAK – This enables or disables the break action of the ENTER key. So what!!

COPY – This is very similar to the C command of NAS SYS except the arguments are in decimal. It is possible to over write your program!! It might be useful for fast action graphics games.

DELAY – The argument ‘n’ causes a delay of nmsec. SET – Already explained.

SPEED – This allows control of the repeat keyboard speeds. The first argument delays the start of the repeat and the second argument is the interval between repeats.

You might have gathered by now that I’m rather impressed with XBASIC and blind to its faults. It does in fact have a few bad points : 1) There is no APPEND which I think is a major ommission. The manual explains how it can be done by saving a listing to cassette, which is almost an admission of the ommission! 2) The starting up of XBASIC is a real bind. The manual indicates that the ROM version of XBASIC does all the initialisation for you. It should be quite easy to modify the tape version to do this too.

3) The manual is very clear and the appendicies are very helpful, but I would have liked an assembly listing of XBASIC, the extra fee would have been well worth it. 4) Despite there being some extremely useful new commands there are in my opinion

some unnecessary ones viz BREAK,XREF or XLIST (they do almost the same thing), CHECK (RENUMBER does this any way) and PRINTS, PUT and VDU are nice but a bit extravagant. I’ve already mentioned I would have liked an APPEND, but another command I would have really liked to see is ‘FIND string and REPLACE with’. I KNOW how useful this would be but I’ve never seen it mentioned anywhere. Is it really that difficult to do? Well I’ll soon find out when I start to attempt adding (and replacing?) commands to XBASIC. 5) The demo program is a bit simple.

CONCLUSION : XBASIC is exceptionally good value for money. The extra commands it gives to ROM BASIC are on the whole very useful, lucidly explained in the manual and easy to use. Further, it is possible to add your own commands to produce a very personal BASTC. XBASIC is available from Level 9 Computing, 229 Hughenden Road, High Wycombe, Bucks., on tape price £15.00 or in ROM price £25.00.


This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 47 of 55