NetNews Usenet Archive 1992 #20/NN_1992_20.iso/spool/comp/sys/acorn/8629

Internet Message Format | 1992-09-13 | 5.7 KB

Path: sparky!uunet!mcsun!uknet!acorn!rwilson
From: [e-mail]
Newsgroups: comp.sys.acorn
Subject: Really! BASIC V in 3.10
Message-ID: <[e-mail]>
Date: 10 Sep 92 17:35:38 GMT
Sender: [e-mail]
Lines: 159

ARM BBC BASIC V: changes between 1.04 and 1.05

(1) BASIC V is internationalised. @% can be set to print "," instead of ".".
All messages are printed via BASICTrans (see TransDoc).

(2) INSTALL was treated as a statement permitting a variety of lethal, innocent
looking BASIC programs along the lines of:

  10 INSTALL"foo"

which wipes out a substantial portion of the interpreter's stack: an error,
local array or any structure causes mayhem. 1.05 series interpreters treat
programs like this as bad: an error is issued if the INSTALL is encountered.
INSTALL is now implemented as a command (and it is therefore impossible to edit
the line containing an INSTALL to the state that a 1.04 interpreter left it).

(3) ADR with bit 1 clear in OPT (0, 2, ..) will no longer give an error in the
circumstance when the label is out of range. (Also bad immediate fields will
not fault).

(4) Fatal errors are *only* 0

(5) @% goes ANSI C

@% is now reported by LVAR in ANSI printf format - one of g, e or f formats
followed by the field width, a dot and the precision. @% is also settable
using this format - @%="G10.9" corresponds to the default. There is now a
HELP message on @% and the formats.

Partial setting of @% is supported:

@%="+":REM turn on STR$
@%="G":REM go to G format (turns off STR$)
@%="10":REM set just the field width for current format (turns off STR$)
@%=".5":REM set just the precision for current format (turns of STR$)
@%="+F10":REM turn on STR$, go to F format and set field width 10
@%="E10.3":REM go to E format, field width 10, 3 digits in total
@%="+F20.4":REM turn on STR$, go to F, field width 20, 4 digits after '.'

Spaces cannot be used. LET @%= does not cope with the string form. Replace
"." with "," to get "," used as the decimal point character.

(6) Improved error messages from libraries

The interpreter will tag the error message with the name of the library
which caused the error message (found from the REM on the first line of a
library.

(7) INPUT# floating values

Both the 5 byte real (&80, value) and the 8 byte real (&88, value) are
accepted by the interpreter.

(8) Sped up array statements

The following have been sped up by some factor between 3 and 10:

foo()=<expression>
foo%()=<expression>
foo()=fie()
foo%()=fie%()
DIM foo(, foo$(, foo%(

(9) END= may be used almost anywhere

Useable anywhere except with INSTALLed libraries, nested within EVAL or LOCAL
ERROR, nested within assignments to local arrays, nested local arrays.

Example:

   10DIM A(10)
   20A(1)=10
   30PROCb
   40PRINTA(1)
   50END
   60DEF PROCb
   70LOCAL A()
   80DIM A(2)
   90A(1)=EXP1
  100PROCMoveEnd(&40000)
  110PRINTA(1)
  120ENDPROC
  130DEF PROCMoveEnd(a)
  140LOCAL A()
  150DIM A(10)
  160A(1)=PI
  170END=a
  180PRINT A(1)
  190ENDPROC

is incorrect since there is a nested local array in PROCb. A direct call to
PROCMoveEnd with no other nested A() would be OK. The interpreter is capable of
detecting the above situation, but can be confused by an EVAL which contains a
END=.

HIMEM gets reset, local arrays cleared if faulty.

(10) TRACE to file

TRACE output can be directed to a file with TRACE TO "<file name>": all TRACE
output is sent to the file until TRACE CLOSE is issued [the interpreter will
close the trace file before exit]. Note that errors found when writing to this
file will result in it being closed and forgotten about. The variable TRACE
allows the programmer to output other things to the trace file (e.g. with
IF TRACE THEN BPUT#TRACE,"X is "+STR$X)

Note that TRACE now allows line number and PROC tracing to be on together:
TRACE PROC:TRACE ON (say).

(11) TEXTLOAD and TEXTSAVE commands

TEXTLOAD <string expression>
TEXTSAVE[O <expression>,] <string expression>

As well as the obvious, TEXTLOAD (and BASIC -load) are safer in that they have
(generally) more free memory to convert the program in than BASIC 1.04 which is
stuck with 4096 bytes.

(12) CRUNCH command

CRUNCH <expression> Strips various spaces from program.
bit 0 = 1: spaces before statements
bit 1 = 1: spaces in statements
bit 2 = 1: REM statements (except on first line)
bit 3 = 1: empty statements
bit 4 = 1: empty lines

Notes:

(a) Programs with -quit set will be CRUNCH %1111 and LIBRARY and INSTALL sub
programs will be CRUNCH %1111. CRUNCH %10 may make a program uneditable.
OVERLAYs will not be CRUNCHed.

(b) BASIC V 1.04 cannot read assembler statements that have been crunched: such
things as EORR4,R4,R5 give it terminal heart burn.

(c) The interpreter has been optimised for fully crunched programs.

(d) CRUNCHing away empty lines will give problems to programs with GOTO (GOSUB,
IF THEN, RESTORE) in them which rely on the target being an empty line (or line
of empty statements or REM statement). RESTORE+ might give a problem if
intervening lines are removed.

(13) Bugs fixed

17-Nov-88   Fixed TAN1E-5 bug (misread the flow chart in Cody and Waite!)
02-Dec-88   -1^-10 blew up
14-Mar-89   " unlistable token " not terminated by >&7F
15-Jun-89   F1XSUB, F1SUB could return -0 which various xxSTAs can't cope with
17-Jul-89   Difference between IF THENELSE and IF THEN ELSE fixed
18-Aug-89   Cache not being flushed on errors could cause problems with EVAL
12-Oct-89   Bug in printing 0 in E mode removed
17-Oct-89   INT-(3*2^30) didn't give error
19-Oct-89   Assembler OPT not reset on -chain or -quit
24-Oct-89   A()=B() messed up
03-Nov-89   Change to ADVAL to return all 32 bits
11-Dec-89   TRACE TO "printer:" didn't work because of the type setting

[Plus other things which I have forgotten!]