Address 52 is the beginning of a string "ABC". Since each ASCII character is one byte, we can assume than address 52 and two consecutive addresses stores "A", "B","C", i.e. address 52 stores "A", address 53 stores "B", address 54 stores "C".

So code to send each byte of the string to the printer,

load R0, 52 (Copies data at address 52 to register 0)

save R0, 1   (Copies data from the register 0 to the printer at address 1)

load R1, 53 (Copies data at address 53 to register 1)

save R1, 1   (Copies data from the register 1 to the printer at address 1)

load R2, 54 (Copies data at address 54 to register 2)

save R2, 1 (Copies data from the register 2 to the printer at address 1)