Ifgt Err Endif

MACRO //CHAR ;Load TRS-80 Screen with //CHAR

LD HL,3C00H ¡Address of first screen location

LD DE.3C01H ¡Address of second screen location

LDIR ¡Move //CHAR to all screen locations

ENDM ¡End of macro LDS

¡Fill screen with blanks

the screen with blanks

A,//CHAR ¡Load A with //CHAR HL,//START ¡Address of first location (HL),A ¡Stuff //CHAR there

DE.//START + 1 ¡Second location BC.//COUNT-1 ¡Size of block - 1

0,7000H,100 ¡Store 100 bytes of 0 at 7000H

¡Some arbitrary code

data set) utility, available at extra cost. PDS lets you build a single library file that contains multiple sub-files and an index header block that points to the sub-files. If you put assembly language subroutines into a PDS file, EDAS IV can search the PDS file and only assemble the subroutines your program uses.

Even if you don't have PDS, you can still selectively assemble using *GET and IFREF. First, you build a file of subroutines, surrounding each subroutine with "IFREF routine-name" and ENFIF. Then you *GET the subroutine file. If your main program REFerences a subroutine, the IFREF test will be true and the subroutine code will be assembled. This method takes longer than *SEARCHing a PDS file since the whole file is processed by *GET, even though only part of it is assembled.

Documentation

EDAS IV's documentation lives up to the quality standards of previous EDAS manuals. The manual is not a tutorial on assembly language programming, but it does explain things clearly and it includes lots of examples. If you can program in Z-80 assembly language, you should be able to learn to use the macro processing features of EDAS IV by reading the manual and experimenting with the examples.

The main text has over 100 pages describing the system. A complete listing of error messages with explanations is given. The format of source, object and cross-reference files is described. The manual has a good table of contents but no index.

Utilities

EDAS IV includes a utility called XREF that generates a cross-reference listing of your assembly program's symbols. If your assembly includes *GET or *SE ARCH directives, the name of the file containing the symbol is indicated on the cross reference. A nice extra is the EQU option. XREF can generate a file containing assembly language EQU statements for the symbols in your program.

TTD is a utility that transfers assembly language source files from tape to disk. It accepts source code produced by Radio Shack's cassette-based EDTASM assembler.

EDAS IV is a powerful program development tool. The fact that Roy Soltoff not only wrote EDAS IV but also uses it extensively has helped to keep the enhancements useful and well-tested. Its macros add a new dimension to Z-80 assembly language programming. If you do much assembly language programming, I urge you to try the combination of LDOS, EDAS IV, and PDS. These products should quickly pay for themselves in savings of your most valuable resource: time.

Rowland Archer

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