diff --git a/gidubba.asm b/gidubba.asm
index c761511..f3bd213 100644
--- a/gidubba.asm
+++ b/gidubba.asm
@@ -335,10 +335,123 @@ setmrk: load    r0, target
 
         ;***
 
-        ;Copy to mark
+        ;Copy to mark (under construction)
 
-        ;Placeholder
-copy:   breq    r0, r0, cmdp
+        ;Find the argument line in the save and store its number
+copy:   cleq    r0, r0, fend
+
+        ;Get the save address of the line
+        ;High byte
+        load    r0, sublod + 1
+        store   test1 + 1, r0
+        store   testa + 1, r0
+        ;Low byte
+        load    r0, sublod + 2
+        store   test1 + 2, r0
+        store   testa + 2, r0
+
+        ;Check for the save end
+testa:  load    r0, 0
+        load    r1, sub
+        breq    r0, r1, cmdp
+
+        ;Restore the buffer start address
+        ;High byte
+        load    r0, bfstrt
+        store   test2 + 1, r0
+        ;Low byte
+        load    r0, bfstrt + 1
+        store   test2 + 2, r0
+
+        ;Initialise the character counter
+        xor     r0, r0
+
+        ;Read a character
+test1:  load    r1, 0
+
+        ;Check for save and buffer ends
+        ;Save end
+        load    r2, sub
+        breq    r1, r2, test3
+        ;Buffer end
+        load    r2, bfsize
+        breq    r0, r2, test3
+
+        ;Store the character in the buffer
+test2:  store   0, r1
+
+        ;Check for line and save ends
+        ;Line end
+        load    r2, lf
+        breq    r1, r2, test4
+
+        ;Increment the character counter and store it in r3
+        ;Increment
+        load    r2, const1
+        cleq    r0, r0, sum
+        ;Store
+        xor     r3, r3
+        xor     r3, r0
+
+        ;Increment the save address
+        ;Low byte
+        load    r0, test1 + 2
+        load    r2, const1
+        cleq    r0, r0, sum
+        store   test1 + 2, r0
+        ;Add the overflow to the high byte
+        load    r0, test1 + 1
+        xor     r2, r2
+        xor     r2, r1
+        cleq    r0, r0, sum
+        store   test1 + 1, r0
+
+        ;Increment the buffer address
+        ;Low byte
+        load    r0, test2 + 2
+        load    r2, const1
+        cleq    r0, r0, sum
+        store   test2 + 2, r0
+        ;Add the overflow to the high byte
+        load    r0, test2 + 1
+        xor     r2, r2
+        xor     r2, r1
+        cleq    r0, r0, sum
+        store   test2 + 1, r0
+
+        ;Reload the character counter to r0
+        xor     r0, r0
+        xor     r0, r3
+
+        ;Read the next character
+        breq    r0, r0, test1
+
+        ;Force line end
+test3:  load    r1, test2 + 1
+        store   test5 ,r1
+        load    r1, test2 + 2
+        store   test5 ,r1
+
+        ;Store the CR of a newline in the buffer
+        load    r0, cr
+test5:  store   0, r0
+
+        ;Increment the buffer address
+        ;Load the address
+        load    r0, test2 + 1
+        load    r1, test2 + 2
+        ;Increment
+        cleq    r0, r0, incdw
+        ;Store the address
+        store   test6 + 1, r0
+        store   test6 + 2, r1
+
+        ;Store the LF of a newline in the buffer
+        load    r0, lf
+test6:  store   0, r0
+
+        ;Return to the command prompt
+test4:  breq    r0, r0, cmdp
 
         ;***
 
@@ -529,7 +642,7 @@ print:  load    r0, cstff
 
         ;***
 
-        ;Write the text to tape
+        ;Write the text to the tape punch
 
         ;Get the tape punch address
         ;High byte
@@ -551,7 +664,7 @@ write:  load    r0, cstff
 
         ;***
 
-        ;Read the text from tape
+        ;Read the text from the tape reader
 
         ;Get the save start address
         ;High byte
@@ -561,11 +674,23 @@ read:   load    r0, svstrt
         load    r0, svstrt + 1
         store   chrsto + 2, r0
 
+        ;Ignore the leader
+iglead: load    r1, fffd
+        xor     r2, r2
+        breq    r1, r2, iglead
+        breq    r0, r0, chkend
+
         ;Read a character
 chread: load    r1, fffd
 
-        ;Check for empty tape reader
-        xor     r2, r2
+        ;Check for trailer or empty tape reader
+        ;Trailer
+chkend: xor     r2, r2
+        brneq   r1, r2, chkntp
+        load    r1, sub
+        breq    r0, r0, chrsto
+        ;Empty tape reader
+chkntp: nand    r2, r2
         brneq   r1, r2, chrsto
         load    r1, sub