XMAS BOX GW-BASIC

Author: Povi
Category: Christmas Challenge
System:   IBM PC
Language: GW-BASIC
Len source code: 120 bytes
Len exe file:    90 bytes
Len code only:   90 bytes

Instructions:
Download GW-BASIC (https://www.abandonwaredos.com/abandonware-game.php?abandonware=GW-BASIC+3&gid=2853), copy gwbasic.exe and BOX.BAS files into a folder (eg. c:\gwbasic)
Download DosBox (https://www.dosbox.com/download.php?main=1)

You can also use PC-BASIC (https://robhagemans.github.io/pcbasic/index.html) instead of the original GW-BASIC, if you don't want to use DosBox. PC-BASIC is a remake of GW-BASIC in Python.
Run DosBox, and type:
mount c c:\gwbasic
c:
gwbasic

In GW-BASIC (or PC-BASIC) type:
LOAD"BOX.BAS
RUN (or press F2)

You can list the source code with the LIST command (or press F1 key and Enter)

Description:
Iterate X and Y coordinates (nested for loops), printed char based on coordinates modulo 9