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Differences from PBASIC

Although ARMbasic has an extremely similar syntax to PBASIC, there are subtle differences, so some legacy code may not compile right away. 32-bits vs. 16-bits

  • ARMbasic is written for 32-bit hardware, and cannot utilize code which depends on 16-bit truncation.
  • The default data type is 32 bits, rather than 16 bits in PBASIC.

Changed due to ambiguity

  • FOR..NEXT is ambiguous for negative STEP. To clarify negative steps use DOWNTO
  • The PBASIC syntax of IN0, DIR0, OUT0 has problems with parameterization. It is replaced by the use of IN(0), DIR(0) and OUT(0).
  • The formatted input of many PBASIC words will in many cases hang waiting for input if it is not of the proper form.  Its better to accept any or all input and then parse it later, but PBASIC does not have that ability.  A simple set of string functions have been added to ARMbasic to interpret input

Design differences

  • Integer variables do not need to be declared.  This is common to most other BASICs. ARMbasic does not require simple variables to be declared before use.
  • As there is much more variable space available, simple BIT, NIBBLE, BYTE types are not supported. Arrays of BYTE also called strings are supported
  • Normal BASIC array declarations are supported using DIM.  Unlike PBASIC syntax.
  • PIN declaration is replaced by treating pins as an array IN(x) vs INx.  This makes parameterization of pins simpler.
  • The standard CONST syntax of most BASICs is used instead of PBASIC CON syntax
  • Multiple statements on a single line are not supported
  • The standard PRINT is used and its syntax is used in place of PBASIC DEBUGOUT
  • Simple statements must be completed on a single line, run on statements are not supported
  • The $ suffix is used to declare strings using the DIM statement
  • Strings use a null (char 0) terminator .
  • CLEAR is used to reset all variables and reset the stack.
  • In an interpreter there is an advantage to having functions such as &\ |\ ^\ ** *\ DIG and DCD   But these are easily done in a compiled BASIC and have no performance or space penalty.

                 x = NOT (a & b)        ' equivalent to a &\ b

                 x = a * b >> 16         ' equivalent to a ** b (for 16 bit values)

                 x = a * b >> 8           ' equivalent to a */ b (for 16 bit values)

                 x = y /1000 mod 10   ' equivalent to y DIG 4

                 x

1<<6                  ' equivalent to DCD 6

  • HYP, TAN and NCD are not implemented in ARMbasic         
  • Many differences will be handled in the PBASIC translator pre-process step (under development)
  • -$hex values are not supported

Design simplifications

 

 

  • Only 1 statement per line is allowed
  • run-on statements are not allowed (continuation to the next line)
  • Formatted input is replaced with elimentary string functions

Archaic commands

  • DTMFOUT is not supported.
  • ON and BRANCH should be coded using SELECT CASE.
  • LOOKUP can use arrays or strings.
  • LOOKDOWN should be coded using SELECT CASE
  • GET, PUT can be replaced with arrays