HP 3000 Manuals HP 3000 Manuals
Differences Relative to BASIC/V For those users familiar with BASIC/V's external procedure call feature, this section describes the differences between that feature and HP Business BASIC/XL's ANYPARM feature, and explains some of the reasons for the differences. Although the ANYPARM feature is designed to provide the same functionality as the BASIC/V feature, it is also designed to be consistent with other aspects of HP Business BASIC/XL. It is not meant to be identical with BASIC/V. An MPE/V machine word in this section refers to the 2 byte machine word of the HP 3000 running with the MPE V operating system. An MPE XL machine word is a 4 byte machine word of the HP 3000 running under the MPE XL operating system. The View from the External Procedure In the BASIC/V feature, the field containing the number of parameters is located at Q+1 of the calling procedure, and the addresses and flag words immediately follow it on the stack. The HP Business BASIC/XL ANYPARM external procedure must declare two formal parameters: one for the number of parameters, and one for the address of the actual parameter table. This was done both to enable the external procedures to be written in Pascal, and to make it easier to migrate the external procedures to future HP computers. Each flag word on MPE XL takes up an entire word and immediately follows the address of the parameter, instead of being packed three to a word and residing together in a block. The change makes it easier to obtain the required information and to port the feature to future computers. The Flag Words Data Types. The values in the flag words that indicate the data types are not the same as those used by BASIC/V. The change was necessary to allow the use of the Business BASIC XL data types that don't exist in BASIC/V. The values are now consistent with the values returned by the HP Business BASIC XL TYP and BUFTYP built-in functions. Sizes. The size field (dimensionality) for a scalar string contains a zero, rather than a one as it did in the BASIC/V feature; the size field for a one-dimensional string array contains a one, rather than a two. The change is required to ensure that strings are handled consistently with the method used in HP Business BASIC/XL. Remember that HP Business BASIC/XL allows string arrays of up to six dimensions, whereas in BASIC/V strings arrays are limited to one dimension. The Addresses For arrays and strings, the address passed to the ANYPARM external references the first byte of the dope vector, rather than the beginning of the data area. All addresses are now byte addresses.