Getting todays weekday name

We will use service 2Ah of Interrupt 21h.

mov  ah,2Ah
int  21h

al = weekday (0-6) (0 = Sunday, 1 = Mon..., etc.)
dh = month (1-12)
dl = day (1-28,29,30, or 31)
cx = year (1980 through 2099)


Try this code:
;-=-=-=-=-=-=-=-=-=-= weekday.asm 
; assembled with NBASM 
; ( http://www.fysnet.net/newbasic.htm ) 
.model tiny
.code
.8086
            org  100h
            mov  ah,2Ah    ; DOS get date
            int  21h       ; returns weekday in AL (0-6)
            .exit          ; will return AL for ERROR_LEVEL
.end
;-=-=-=-=-=-=-=-=-=-=

Now, if you call this from your bat file, it will return 
0 - 6 in ERRORLEVEL. 


@echo off
weekday.com
IF ERRORLEVEL 0 IF NOT ERRORLEVEL 1 echo Sunday
IF ERRORLEVEL 1 IF NOT ERRORLEVEL 2 echo Monday
IF ERRORLEVEL 2 IF NOT ERRORLEVEL 3 echo Tuesday
IF ERRORLEVEL 3 IF NOT ERRORLEVEL 4 echo Wednesday
IF ERRORLEVEL 4 IF NOT ERRORLEVEL 5 echo Thursday
IF ERRORLEVEL 5 IF NOT ERRORLEVEL 6 echo Friday
IF ERRORLEVEL 6 echo Saturday