Embedding dates into assembler source
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It is useful to embed version dates into code, however most Z80 assemblers don't
easily manipulate strings to allow this. For example, with my PDP11 assembler I
can do the following:

VersDD:   equ	06
VersMM$:  equ	"Nov"
VersYY:   equ	2015

          defb  48+(VersDD/10),48+(VersDD MOD 10)
          defb  "-"+VersM$+"-"+STR$(VersYY)

This is not possible on most assembers. I have worked out the following code that
works with ZMAC, and it likely to work with other assemblers.

Vers     EQU  100
VersDD   EQU  06
VersMM   EQU  11
VersYY   EQU  2015

         DEFB 'v','0'+((Vers / 100) MOD 10),'.'
         DEFB '0'+((Vers / 10) MOD 10),'0'+(Vers MOD 10),' '
         DEFB '0'+(VersDD / 10),'0'+(VersDD MOD 10),'-'
         DEFB 74-4*(VersMM=2)+3*(VersMM=3 | VersMM=5)-9*(VersMM=4 | VersMM=8)+9*(VersMM=9)+5*(VersMM=10)+4*(VersMM=11)-6*(VersMM=12)
         DEFB 97+4*(VersMM=2 | VersMM=9 | VersMM=12)+15*(VersMM=4)+20*(VersMM=6 | VersMM=7 | VersMM=8)+2*(VersMM=10)+14*(VersMM=11)
         DEFB 110-12*(VersMM=2)+4*(VersMM=3 | VersMM=4)+11*(VersMM=5)-2*(VersMM=7)-7*(VersMM=8)+2*(VersMM=9)+6*(VersMM=10)+8*(VersMM=11)-11*(VersMM=12)
         DEFB '-','0'+((VersYY / 1000) MOD 10),'0'+((VersYY / 100) MOD 10)
         DEFB '0'+((VersYY / 10) MOD 10),'0'+(VersYY MOD 10)

This assembles a string in the format "v1.00 06-Nov-2015".