diff --git a/twasm/asm/main.asm b/twasm/asm/main.asm
index d607021..b958731 100644
--- a/twasm/asm/main.asm
+++ b/twasm/asm/main.asm
@@ -51,8 +51,7 @@ start:
   call clear_token_table
   call clear_label_tables
 
-  mov rdi, program        ; -> program
-  mov rsi, [program.size] ; = size of program
+  mov rdi, program
   call tokenise
   ; rax = number of tokens in token table
   mov rdi, rax
@@ -104,10 +103,13 @@ assemble:
             ; al = type
     pop rdi ; di = tte
 
-    cmp al, 0x1           ; check if next tte is an operator
-    je .operator          ; if so, handle
+    cmp al, 0x1  ; check if next tte is an operator
+    je .operator
 
-    cmp al, 0x4           ; check if next tte is a label
+    cmp al, 0x3  ; check if next tte is a pseudo-operator
+    je .pseudo_operator
+
+    cmp al, 0x4  ; check if next tte is a label
     je .label
 
     jmp .unexpected_token ; otherwise, fail
@@ -123,6 +125,39 @@ assemble:
     and edi, 0x0FFF      ; edi = index to add address hash to
     call add_label_address
     jmp .loop_next_token
+  .pseudo_operator:
+    push rsi
+    mov rsi, .msg_pseudo_operator
+    call print.debug
+    pop rsi
+
+    cmp di, 0x0100
+    je .pseudo_operator_db
+    jmp .unexpected_token
+  .pseudo_operator_db:
+    call .next_token
+    jge .break
+    call .get_next_tte
+
+    cmp di, 0x2000
+    jne .unexpected_token
+
+    call .next_token
+    jge .break
+
+    mov ecx, [.tokens_processed]
+    mov rax, [TOKEN_TABLE_ADDR + 2 * rcx] ; get the next 8 bytes from the tt
+    mov ecx, [.buffer_pointer]
+    mov [rcx], rax                        ; and add them to the buffer
+    add ecx, 8
+    mov [.buffer_pointer], ecx
+    call .next_token
+    jge .break
+    call .next_token
+    jge .break
+    call .next_token
+    jge .break
+    jmp .loop_next_token
   .operator:
     push rdi
     ; di = tte of operator
@@ -905,7 +940,7 @@ assemble:
     mov rsi, .msg_break
     call print.debug
     pop rsi
-    ret
+    jmp halt
 
   .unexpected_token:
     call .flush_write_buffer
@@ -1037,7 +1072,7 @@ assemble:
   .msg_operator_2_register_memory db "operator_2_register_memory", 0x0A, 0x00
   .msg_operator_2_register_register db "operator_2_register_register", 0x0A, 0x00
   .msg_operator_2_register_const db "operator_2_register_const", 0x0A, 0x00
-  .msg_potential_label db "potential_label", 0x0A, 0x00
+  .msg_pseudo_operator db "pseudo_operator", 0x0A, 0x00
 
 ; ------------------------------------------------------------------------------
 ; get_tte_type
@@ -1075,7 +1110,10 @@ get_tte_type:
 
     mov cx, [tokens.by_id + eax * 4] ; next entry in tokens.by_id
 
-    cmp cx, di
+    cmp di, 0x0100
+    je .pseudo_operator
+
+    cmp di, cx
     je .found
 
     inc eax
@@ -1088,7 +1126,9 @@ get_tte_type:
     mov eax, UNRECOGNISED_ID_TYPE
     and eax, 0xF
     ret
-
+  .pseudo_operator:
+    mov eax, 0x3
+    ret
   .label:
     mov eax, 0x4
     ret
@@ -1293,15 +1333,13 @@ get_reg_bits:
 
 ; ------------------------------------------------------------------------------
 ; tokenise
-; TODO write tests
 ;
 ; description:
-; represents the program at the given address and puts it in the token table
-; it's probably desirable to clear the token table before calling this function.
+; creates a tokenised definition of the null-terminated program at rdi and puts
+; it in memory at TOKEN_TABLE_ADDR
 ;
 ; parameters:
 ; rdi -> first byte of program
-; rsi = size of program in bytes
 ;
 ; returned:
 ; rax = number of tokens processed
@@ -1309,16 +1347,15 @@ get_reg_bits:
 
 tokenise:
                ; rdi -> current byte of program
-  add rsi, rdi ; rsi -> last byte of program
   xor eax, eax ; rax = number of tokens processed
   xor edx, edx ; dl = current byte of program
 
   .loop:
-    cmp rdi, rsi ; if current byte greater than last byte
-    jge .break   ; then break
-
     mov dl, [rdi] ; dl = current byte
 
+    cmp dl, 0x00 ; if current byte is null
+    je .break    ; then break
+
     cmp dl, ";" ; if current byte is the start of a comment
     je .comment ; then handle the comment
 
@@ -1328,7 +1365,6 @@ tokenise:
     cmp dl, "," ; if current byte is a comma
     je .comma   ; then handle the comma
 
-    push rsi
     push rdi
     push rax
     push rdx
@@ -1341,7 +1377,6 @@ tokenise:
     pop rdx ; dl = current byte
     pop rax ; rax = number of tokens processed
     pop rdi ; rdi -> current byte of program
-    pop rsi ; rsi -> last byte of program
     jnz .skip_byte_whitespace
 
     test byte [.expecting], E_LABEL    ; check if a label is expected
@@ -1351,12 +1386,10 @@ tokenise:
     jmp .operand                       ; else, handle as an operand
 
   .comment:
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_comment
     call print
-    pop rsi ; rsi -> last byte of program
 
     test byte [.expecting], E_COMMENT ; make sure a comment is expected
     jz .unexpected_comment            ; if not, error
@@ -1367,8 +1400,6 @@ tokenise:
     je .comment_break ; then break
 
     inc rdi           ; point to next unread byte
-    cmp rdi, rsi
-    jge .break
     jmp .comment_loop
   .comment_break:
     jmp .loop
@@ -1380,12 +1411,10 @@ tokenise:
     jmp .loop                            ; else, loop
 
   .comma: ; found comma
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_comma
     call print
-    pop rsi
 
     test byte [.expecting], E_COMMA            ; make sure a comma was expected
     jz .unexpected_comma                       ; if not, error
@@ -1394,12 +1423,10 @@ tokenise:
     jmp .loop                                  ;       and loop
 
   .newline_mk_flags:
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_newline
     call print
-    pop rsi
 
     test byte [.expecting], E_NEWLINE ; make sure a newline was expected
     jz .unexpected_newline            ; if not, error
@@ -1425,20 +1452,15 @@ tokenise:
     cmp dl, ";"
     je .label_not_found
     inc eax ; inc byte counter
-    cmp rdi, rsi
-    jge .break
     jmp .label_loop
   .label_break:
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_label
     call print
-    pop rsi ; rsi -> last byte of program
 
     push rax
     push rdi
-    push rsi
 
     mov rsi, rdi ; rsi -> start of string
     mov rdi, rax ; rdi = size of string
@@ -1451,7 +1473,6 @@ tokenise:
     and cx, 0x0FFF
     or cx, 0x3000
 
-    pop rsi ; rsi -> last byte of program
     pop rdi ; rdi -> current byte of program
     pop rax ; rax = number of bytes in label
 
@@ -1492,11 +1513,9 @@ tokenise:
     mov [.pending_operator + eax], dl
 
     inc eax            ; inc byte counter
-    inc rdi            ; inc byte pointer
     cmp eax, 4              ; check that operator is short enough
     jg .unexpected_operator ; if not, error
-    cmp rdi, rsi
-    jge .break
+    inc rdi            ; inc byte pointer
     jmp .operator_loop ; and loop
   .operator_break:
     push rdi
@@ -1507,8 +1526,10 @@ tokenise:
     push rcx
     mov ecx, eax ; cx = operator's token ID
     mov edi, eax ; di = operator's token ID
+    push rcx
     call get_tte_type
     ; al = token type
+    pop rcx ; cx = operator's token ID
     mov sil, al
     pop rax      ; rax = tokens processed
     pop rdi      ; rdi = byte counter
@@ -1520,13 +1541,10 @@ tokenise:
     jne .unexpected_operator
 
     ; debug message
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_operator
     call print
-    pop rsi
-
 
     mov [TOKEN_TABLE_ADDR + rax * 2], cx
     inc rax ; plus 1 token processed
@@ -1535,26 +1553,21 @@ tokenise:
     jmp .loop
 
   .pseudo_operator:
-    ; debug message
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_pseudo_operator
     call print
-    pop rsi
 
     mov [TOKEN_TABLE_ADDR + rax * 2], cx
+    inc rax
     mov byte [.expecting], E_COMMENT | E_NEWLINE | E_WHITESPACE | E_OPERAND
     jmp .loop
 
   .operand:
-    ; debug message
-    push rsi
     mov rsi, .found
     call print.debug
     mov rsi, .msg_operand
     call print
-    pop rsi
 
     test byte [.expecting], E_OPERAND ; make sure an operand was expected
     jz .unexpected_operand            ; if not, error
@@ -1571,8 +1584,6 @@ tokenise:
     je .operand_break
     cmp dl, 0x00
     je .operand_break
-    cmp dl, ";"
-    je .operand_break
 
     inc rax ; inc length counter
     inc rdi ; inc byte pointer
@@ -1580,7 +1591,6 @@ tokenise:
   .operand_break:
     pop rdi  ; rdi -> first byte of operand
     push rdi
-    push rsi
     mov rsi, rax ; rsi = length of operand in bytes
 
     mov cx, ax ; cx = length counter for safe keeping
@@ -1589,7 +1599,6 @@ tokenise:
     ; dl = return code
     ; rax = binary data
     pop rcx
-    pop rsi
     pop rdi      ; rdi = first byte of operand
     add di, cx   ; rdi = last byte of operand
     mov rcx, rax ; rcx = evaluate_operand's binary return data
@@ -1649,52 +1658,40 @@ tokenise:
   .expecting db E_COMMENT | E_NEWLINE | E_WHITESPACE | E_OPERATOR | E_LABEL
 
   .unexpected_whitespace:
-    push rsi
     mov rsi, .err_unexpected
     call print.error
     mov rsi, .msg_whitespace
     call print
-    pop rsi
     jmp halt
   .unexpected_comment:
-    push rsi
     mov rsi, .err_unexpected
     call print.error
     mov rsi, .msg_comment
     call print
-    pop rsi
     jmp halt
   .unexpected_newline:
-    push rsi
     mov rsi, .err_unexpected
     call print.error
     mov rsi, .msg_newline
     call print
-    pop rsi
     jmp halt
   .unexpected_comma:
-    push rsi
     mov rsi, .err_unexpected
     call print.error
     mov rsi, .msg_comma
     call print
-    pop rsi
     jmp halt
   .unexpected_operand:
-    push rsi
     mov rsi, .err_unexpected
     call print.error
     mov rsi, .msg_operand
     call print
-    pop rsi
     jmp halt
   .unexpected_operator:
-    push rsi
     mov rsi, .err_unexpected
     call print.error
     mov rsi, .msg_operator
     call print
-    pop rsi
     jmp halt
   .err_unexpected db "unexpected ", 0x00
   .found db "found ", 0x00
@@ -1805,6 +1802,8 @@ evaluate_operand:
     call evaluate_constant
     ; dl = type of constant
     ; rax = hex value of constant
+
+    ; these are intentionally swapped; `djb2` call in .label takes this order
     pop rdi ; rdi = size of label in bytes
     pop rsi ; rsi -> first byte of label
 
@@ -1976,8 +1975,7 @@ evaluate_constant:
     jmp .bin_loop
 
   .chr:
-    cmp rcx, 4       ; ensure char is only 4 bytes long
-    jg .unrecognised
+    ; TODO check for overlength string and do something; probably in `tokenise`
     cmp rsi, 1 ; range check
     je .chr_break
 
@@ -3165,6 +3163,7 @@ msg_halt db "halted.", 0x0A, 0x00
 whitespace_2 db " ", 0x0D
 
 ; test program
+align 128
 program:
   db "print:", 0x0A
   db "  push rdx", 0x0A
@@ -3235,7 +3234,7 @@ program:
   db '    db "[WARN]: "', 0x0A
   db "    db 0x1B", 0x0A
   db '    db "[0m"', 0x0A
-  db "    db 0x00", 0x0A
-  .size dq $ - program
+  db "    db 0x00", 0x0A, 0x00
+program_end:
 
 msg_end db "end of the binary ->|", 0x0A, 0x00