TReed.ES@XEROX.ARPA (08/21/85)
Quoteing verbatum from the DBase manual I have, "SET CALL TO <address> Sets the decimal address that will be called by dBASE CALL command. CALL [<memvar>] Performs a machine language call to the address set by a SET CALL TO or the default address if no SET CALL has been done. There are about 254 bytes of stack available, the HL register pair points to the first byte if the <memvar> was a character string. It is most important that no attempts be made to lengthen or shorten a character string. Control can be passed back to dBASE with a RET instruction." The above is the sum total about the CALL instruction, that I have in my manual. I have used the combination SET CALL TO <address> and then CALL (with no <memvar>) with a RET in the machine language code, and that functions as expected, however, my questions are: 1. What is the DEFAULT address, to which the documentation alludes? 2. "There are about 254 bytes of stack available", where? Starting at the default address? 3. What is the function of <memvar>? Is it to pass a parameter to the machine language routine? Give an example. 4. "the HL register pair points to the first byte if the <memvar> was a character string" the first byte of what, the <memvar> address? Any answers would be apperciated. Thanks --Terry