5826 Southwest Ave.
St.Louis, MO 63139
April 18, 1982
FILES
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CROWLINK: These are the linkages between CP/M and the Crowe Z-80
assembler. I bought this assembler two years ago from Byte Nybbles
for $4! It was available only as an assembly listing and so I
entered it manually in machine language. The assembler is quite
good providing all the features of Zilog's assembler except for
macros, conditional assembly and lower case. It was written to be
used with cassette or paper tape, with the desired pass number
entered from the console. For each pass, the source is re-read and
the appropriate output generated. Pass 1 builds the symbol table
and is required. Pass 2 outputs the assembly listing, pass 3 writes
Intel format hex object and pass 4 gives an assembly listing of
those lines containing errors on the console.
The linkage routines are written so that the assembler can be
run as a standard CP/M .COM file with the following command format.
CROWEASM FILENAME.YY The characters in the normal file extension
position are Y/N selects (default is Y), the first for listing file
and the second for the hex object file. The source must have a file
extension of .Z80 while the listing is created with an extension of
.PRN and the object with an extension of .HEX. Only minimal error
checking and reporting is done. If no source file with the correct
name is found a message is displayed. If any other disk error on a
BDOS call occurs, that is reported. In either case, the routine
waits for a keystroke before exiting to CP/M.
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An additional note about the assembler the way it stands: there
is a limit of 32 characters for a quoted string as operand of a DEFM
statement. If this limit is exceeded NO error message is generated, the
string is truncated. If you're not careful, the terminating '$' for
a CP/M output string could be lost and the results would be unpredictable.
The CROWE.Z80 file has the linkages incorporated into it, near the
end. As it now stands, the symbol table is limited only by the amount of
available memory since the assembler reads the start address of BDOS from
locations 6&7 and sets that as the top of available symbol space.
There has been one minor improvement to the assembler: you can now
specify that the .LST or .HEX files should be sent to drive B rather than
the current default drive by putting a B in the proper position in the
normal filename extension. E.g. CROWE2 CROWE.NB would assemble the file
CROWE.Z80, skip the .LST file and send the .HEX file to drive B. The
source file must still reside on the same drive as the assembler.
When you try to assemble CROWE.Z80 with
CROWE2 the six EX AF,AF' instructions are flagged as syntax errors for
no apparent reason. If you assemble the file EXAF.Z80 it assembles those
instructions as expected. Very strange! In addition, it flags as un-
defined the symbol LBFSZ in the instruction LD B,LBFSZ-1. Again, cause
unknown. The assembler will assemble itself if you change the six
EX AF,AF' commands to DEFB 8 commands.
The source is currently set up for the CROWE2 assembler. To
assemble it with M80 you will need to add ASEG and .Z80 commands to it.
