diff --git a/Makefile b/Makefile
index 39fae9b..cd593b8 100644
--- a/Makefile
+++ b/Makefile
@@ -4,8 +4,8 @@ LDFLAGS =
 TARGET =
 CXX = $(TARGET)g++
 
-OBJS = main.o fromstring.o addressing_mode.o codec.o parser.o
-HEADERS = $(wildcard *.h)
+OBJS = main.o tostring.o fromstring.o addressing_mode.o codec.o parser.o symbol.o
+HEADERS = $(wildcard *.hh)
 
 all: main
 
diff --git a/assembler.hh b/assembler.hh
index 5d26e38..212a232 100644
--- a/assembler.hh
+++ b/assembler.hh
@@ -3,6 +3,8 @@
 #include <optional>
 #include <variant>
 #include <vector>
+#include <memory>
+#include <unordered_map>
 
 #include "isa.hh"
 
@@ -24,7 +26,27 @@ namespace assembler {
     isa::mode mode;
     std::variant<literal_t, reference_t, implied_t> value;
     size_t location;
+    ssize_t row; // debug
   };
 
-  using program_t = std::vector<instruction_t>;
+  struct blob_t {
+    struct {
+      size_t start;
+      size_t start_l;
+      size_t start_h;
+      size_t size_l;
+      size_t size_h;
+    } symbol;
+    size_t location;
+    std::shared_ptr<std::string> buf;
+  };
+
+  using program_t = std::vector<std::variant<instruction_t, blob_t>>;
+
+  struct symbol_strings_t {
+    size_t current_symbol;
+    std::unordered_map<std::string, size_t> map;
+  };
+
+  using symbol_table_t = std::unordered_map<size_t, size_t>;
 }
diff --git a/codec.cc b/codec.cc
index 083d6c4..2d24abe 100644
--- a/codec.cc
+++ b/codec.cc
@@ -10,7 +10,7 @@ namespace codec {
   const std::map<std::tuple<isa::op, isa::mode>, uint8_t>& encode() {
     static const std::map<std::tuple<isa::op, isa::mode>, uint8_t> _ = {
       {{isa::op::BRK, isa::mode::S}, 0},
-      {{isa::op::ORA, isa::mode::ZPX}, 1},
+      {{isa::op::ORA, isa::mode::ZPII}, 1},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 2},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 3},
       {{isa::op::TSB, isa::mode::ZP}, 4},
@@ -19,7 +19,7 @@ namespace codec {
       {{isa::op::RMB0, isa::mode::ZP}, 7},
       {{isa::op::PHP, isa::mode::S}, 8},
       {{isa::op::ORA, isa::mode::IMM}, 9},
-      {{isa::op::ASL, isa::mode::A}, 10},
+      {{isa::op::ASL, isa::mode::ACC}, 10},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 11},
       {{isa::op::TSB, isa::mode::A}, 12},
       {{isa::op::ORA, isa::mode::A}, 13},
@@ -36,7 +36,7 @@ namespace codec {
       {{isa::op::RMB1, isa::mode::ZP}, 23},
       {{isa::op::CLC, isa::mode::I}, 24},
       {{isa::op::ORA, isa::mode::AIY}, 25},
-      {{isa::op::INC, isa::mode::A}, 26},
+      {{isa::op::INC, isa::mode::ACC}, 26},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 27},
       {{isa::op::TRB, isa::mode::A}, 28},
       {{isa::op::ORA, isa::mode::AIX}, 29},
@@ -53,7 +53,7 @@ namespace codec {
       {{isa::op::RMB2, isa::mode::ZP}, 39},
       {{isa::op::PLP, isa::mode::S}, 40},
       {{isa::op::AND, isa::mode::IMM}, 41},
-      {{isa::op::ROL, isa::mode::A}, 42},
+      {{isa::op::ROL, isa::mode::ACC}, 42},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 43},
       {{isa::op::BIT, isa::mode::A}, 44},
       {{isa::op::AND, isa::mode::A}, 45},
@@ -70,7 +70,7 @@ namespace codec {
       {{isa::op::RMB3, isa::mode::ZP}, 55},
       {{isa::op::SEC, isa::mode::I}, 56},
       {{isa::op::AND, isa::mode::AIY}, 57},
-      {{isa::op::DEC, isa::mode::A}, 58},
+      {{isa::op::DEC, isa::mode::ACC}, 58},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 59},
       {{isa::op::BIT, isa::mode::AIX}, 60},
       {{isa::op::AND, isa::mode::AIX}, 61},
@@ -87,7 +87,7 @@ namespace codec {
       {{isa::op::RMB4, isa::mode::ZP}, 71},
       {{isa::op::PHA, isa::mode::S}, 72},
       {{isa::op::EOR, isa::mode::IMM}, 73},
-      {{isa::op::LSR, isa::mode::A}, 74},
+      {{isa::op::LSR, isa::mode::ACC}, 74},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 75},
       {{isa::op::JMP, isa::mode::A}, 76},
       {{isa::op::EOR, isa::mode::A}, 77},
@@ -121,7 +121,7 @@ namespace codec {
       {{isa::op::RMB6, isa::mode::ZP}, 103},
       {{isa::op::PLA, isa::mode::S}, 104},
       {{isa::op::ADC, isa::mode::IMM}, 105},
-      {{isa::op::ROR, isa::mode::A}, 106},
+      {{isa::op::ROR, isa::mode::ACC}, 106},
       //{{isa::op::O_INVALID, isa::mode::M_INVALID}, 107},
       {{isa::op::JMP, isa::mode::AI}, 108},
       {{isa::op::ADC, isa::mode::A}, 109},
@@ -287,7 +287,7 @@ namespace codec {
   const std::map<uint8_t, std::tuple<isa::op, isa::mode>>& decode() {
     static const std::map<uint8_t, std::tuple<isa::op, isa::mode>> _ = {
       {0, {isa::op::BRK, isa::mode::S}},
-      {1, {isa::op::ORA, isa::mode::ZPX}},
+      {1, {isa::op::ORA, isa::mode::ZPII}},
       //{2, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       //{3, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {4, {isa::op::TSB, isa::mode::ZP}},
@@ -296,7 +296,7 @@ namespace codec {
       {7, {isa::op::RMB0, isa::mode::ZP}},
       {8, {isa::op::PHP, isa::mode::S}},
       {9, {isa::op::ORA, isa::mode::IMM}},
-      {10, {isa::op::ASL, isa::mode::A}},
+      {10, {isa::op::ASL, isa::mode::ACC}},
       //{11, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {12, {isa::op::TSB, isa::mode::A}},
       {13, {isa::op::ORA, isa::mode::A}},
@@ -313,7 +313,7 @@ namespace codec {
       {23, {isa::op::RMB1, isa::mode::ZP}},
       {24, {isa::op::CLC, isa::mode::I}},
       {25, {isa::op::ORA, isa::mode::AIY}},
-      {26, {isa::op::INC, isa::mode::A}},
+      {26, {isa::op::INC, isa::mode::ACC}},
       //{27, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {28, {isa::op::TRB, isa::mode::A}},
       {29, {isa::op::ORA, isa::mode::AIX}},
@@ -330,7 +330,7 @@ namespace codec {
       {39, {isa::op::RMB2, isa::mode::ZP}},
       {40, {isa::op::PLP, isa::mode::S}},
       {41, {isa::op::AND, isa::mode::IMM}},
-      {42, {isa::op::ROL, isa::mode::A}},
+      {42, {isa::op::ROL, isa::mode::ACC}},
       //{43, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {44, {isa::op::BIT, isa::mode::A}},
       {45, {isa::op::AND, isa::mode::A}},
@@ -347,7 +347,7 @@ namespace codec {
       {55, {isa::op::RMB3, isa::mode::ZP}},
       {56, {isa::op::SEC, isa::mode::I}},
       {57, {isa::op::AND, isa::mode::AIY}},
-      {58, {isa::op::DEC, isa::mode::A}},
+      {58, {isa::op::DEC, isa::mode::ACC}},
       //{59, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {60, {isa::op::BIT, isa::mode::AIX}},
       {61, {isa::op::AND, isa::mode::AIX}},
@@ -364,7 +364,7 @@ namespace codec {
       {71, {isa::op::RMB4, isa::mode::ZP}},
       {72, {isa::op::PHA, isa::mode::S}},
       {73, {isa::op::EOR, isa::mode::IMM}},
-      {74, {isa::op::LSR, isa::mode::A}},
+      {74, {isa::op::LSR, isa::mode::ACC}},
       //{75, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {76, {isa::op::JMP, isa::mode::A}},
       {77, {isa::op::EOR, isa::mode::A}},
@@ -398,7 +398,7 @@ namespace codec {
       {103, {isa::op::RMB6, isa::mode::ZP}},
       {104, {isa::op::PLA, isa::mode::S}},
       {105, {isa::op::ADC, isa::mode::IMM}},
-      {106, {isa::op::ROR, isa::mode::A}},
+      {106, {isa::op::ROR, isa::mode::ACC}},
       //{107, {isa::op::O_INVALID, isa::mode::M_INVALID}},
       {108, {isa::op::JMP, isa::mode::AI}},
       {109, {isa::op::ADC, isa::mode::A}},
diff --git a/main.cc b/main.cc
index da8f49a..12d6f10 100644
--- a/main.cc
+++ b/main.cc
@@ -2,83 +2,69 @@
 #include <fstream>
 #include <iostream>
 #include <unordered_map>
+#include <memory>
 
 #include "assembler.hh"
 #include "addressing_mode.hh"
 #include "codec.hh"
 #include "parser.hh"
+#include "tostring.hh"
+#include "symbol.hh"
 
-using symbol_table_t = std::unordered_map<size_t, assembler::program_t::const_iterator>;
+using namespace std::literals;
 
-bool resolve_symbols(assembler::program_t& program, symbol_table_t& symbol_table)
+void serialize_program(const assembler::program_t& program, const assembler::symbol_table_t &symbol_table, std::ostream& out)
 {
-  size_t offset = 0;
+  auto serialize_instruction = [&](assembler::instruction_t& ins) -> void {
+    //std::cerr << "enc " << (int)ins.op << ' ' << (int)ins.mode << '\n';
+    char buf[3];
 
-  for (auto ins = program.begin(); ins != program.end(); ins++) {
-    if (ins->symbol != std::nullopt) {
-      auto [_, ok] = symbol_table.insert({*(ins->symbol), ins});
-      if (!ok) {
-        std::cout << "duplicate symbol\n";
-        return false;
-      }
-
-      std::cout << *(ins->symbol) << ' ' << offset << '\n';
+    auto opcode_it = codec::encode().find({ins.op, ins.mode});
+    if (opcode_it == codec::encode().end()) {
+      std::cerr << ins.row << ": illegal op,mode: "
+                << tostring::op().find(ins.op)->second << ' '
+                << tostring::mode().find(ins.mode)->second << '\n';
+      return;
     }
 
-    ins->location = offset;
-
-    auto am_it = addressing_mode().find(ins->mode);
-    assert (am_it != addressing_mode().end());
-    offset += 1 + am_it->second.len;
-  }
-
-  return true;
-}
-
-void serialize_program(const assembler::program_t& program, const symbol_table_t &symbol_table, size_t link_location, std::ostream& out)
-{
-  char buf[3];
-
-  for (auto ins = program.cbegin(); ins != program.cend(); ins++) {
-    std::cerr << "enc " << (int)ins->op << ' ' << (int)ins->mode << '\n';
-    auto opcode_it = codec::encode().find({ins->op, ins->mode});
-    assert (opcode_it != codec::encode().end());
-
     buf[0] = opcode_it->second;
 
-    auto am_it = addressing_mode().find(ins->mode);
+    auto am_it = addressing_mode().find(ins.mode);
     assert (am_it != addressing_mode().end());
 
     auto get_value = [&]() -> ssize_t {
-      if (std::holds_alternative<assembler::reference_t>(ins->value)) {
-        assembler::reference_t ref = std::get<assembler::reference_t>(ins->value);
+      if (std::holds_alternative<assembler::reference_t>(ins.value)) {
+        assembler::reference_t ref = std::get<assembler::reference_t>(ins.value);
         auto sym_it = symbol_table.find(ref.symbol);
-        assert (sym_it != symbol_table.end());
-        auto ref_ins = sym_it->second;
-        if (ins->mode == isa::mode::R) {
-          std::cout << "relative\n";
-          ssize_t offset = static_cast<ssize_t>(ref_ins->location) - static_cast<ssize_t>(ins->location + 2);
+        if (sym_it == symbol_table.end()) {
+          std::cerr << "get_value: " << ref.symbol << '\n';
+          assert(false);
+        }
+        auto ref_location = sym_it->second;
+        if (ins.mode == isa::mode::R) {
+          ssize_t offset = static_cast<ssize_t>(ref_location) - static_cast<ssize_t>(ins.location + 2);
           return offset;
         } else {
-          return ref_ins->location + link_location;
+          return ref_location;
         }
-      } else if (std::holds_alternative<assembler::literal_t>(ins->value)) {
-        assembler::literal_t lit = std::get<assembler::literal_t>(ins->value);
+      } else if (std::holds_alternative<assembler::literal_t>(ins.value)) {
+        assembler::literal_t lit = std::get<assembler::literal_t>(ins.value);
         return lit.num;
-      } else if (std::holds_alternative<assembler::implied_t>(ins->value)) {
-        assert (std::holds_alternative<assembler::implied_t>(ins->value));
+      } else if (std::holds_alternative<assembler::implied_t>(ins.value)) {
+        //assert (std::holds_alternative<assembler::implied_t>(ins.value));
+        return 0;
       } else {
         assert (false);
       }
-      return 0;
     };
 
     size_t value = get_value();
     if (!am_it->second.valid(value)) {
-      std::cout << "overflow at h" << std::hex << ins->location << '\n';
+      std::cerr << "overflow at " << ins.row << " value: " << value << '\n';
+      return;
     }
 
-    std::cout << "value " << std::hex << value << ' ' << am_it->second.len << '\n';
+    //std::cerr << "value " << std::hex << value << ' ' << am_it->second.len << '\n';
 
     if (am_it->second.len >= 2)
       buf[2] = (value >> 8) & 0xff;
@@ -86,6 +72,19 @@ void serialize_program(const assembler::program_t& program, const symbol_table_t
       buf[1] = (value >> 0) & 0xff;
 
     out.write(buf, 1 + am_it->second.len);
+  };
+
+
+  for (auto prog_it = program.cbegin(); prog_it != program.cend(); prog_it++) {
+    if (std::holds_alternative<assembler::instruction_t>(*prog_it)) {
+      auto ins = std::get<assembler::instruction_t>(*prog_it);
+      serialize_instruction(ins);
+    } else if (std::holds_alternative<assembler::blob_t>(*prog_it)) {
+      auto blob = std::get<assembler::blob_t>(*prog_it);
+      out.write(blob.buf->data(), blob.buf->size());
+    } else {
+      assert (false);
+    }
   }
 }
 
@@ -96,41 +95,66 @@ int main(int argc, char * argv[])
     return -1;
   }
 
-  std::string input_filename {argv[1]};
-  std::ifstream is {input_filename, std::ios::binary | std::ios::ate};
-  if (!is.is_open()) {
-    std::cerr << "failed to open " << input_filename << '\n';
-    return -1;
-  }
-
-  auto size = is.tellg();
-  std::string buf(size, '\0'); // construct string to stream size
-  is.seekg(0);
-  is.read(buf.data(), size);
-  is.close();
-
-
   assembler::program_t program;
-  symbol_table_t symbol_table;
+  assembler::symbol_strings_t symbol_strings;
+  symbol_strings.current_symbol = 0;
+  assembler::symbol_table_t symbol_table;
+
   bool ok;
 
-  ok = parser::parse(buf, program);
+  for (int i = 1; i < (argc - 1); i++) {
+    std::cerr << "input[" << i << "]: " << argv[i] << '\n';
+    std::string input_filename {argv[i]};
+    std::ifstream is {input_filename, std::ios::binary | std::ios::ate};
+    if (!is.is_open()) {
+      std::cerr << "failed to open " << input_filename << '\n';
+      return -1;
+    }
+
+    auto size = is.tellg();
+    auto buf = std::make_unique<std::string>(size, '\0'); // construct string to stream size
+    is.seekg(0);
+    is.read(buf->data(), size);
+    is.close();
+
+    std::string_view ext = input_filename.substr(input_filename.size() - 4, 4);
+    if (ext == ".asm"s) {
+      ok = parser::parse(*buf, program, symbol_strings);
+      if (!ok)
+        return -1;
+    } else if (ext == ".bin"s) {
+      std::string name = input_filename.substr(0, input_filename.size() - 4);
+      assembler::blob_t blob {
+        .symbol = {
+          .start = symbol::get(symbol_strings, "_bin_"s + name + "_start"s),
+          .start_l = symbol::get(symbol_strings, "_bin_"s + name + "_start_l"s),
+          .start_h = symbol::get(symbol_strings, "_bin_"s + name + "_start_h"s),
+          .size_l = symbol::get(symbol_strings, "_bin_"s + name + "_size_l"s),
+          .size_h = symbol::get(symbol_strings, "_bin_"s + name + "_size_h"s),
+        },
+        .location = 0xeeee,
+        .buf = std::move(buf),
+      };
+      program.push_back(blob);
+    } else {
+      std::cerr << "unknown extension: " << ext << '\n';
+      return -1;
+    }
+  }
+
+  ok = symbol::resolve(0xc000, program, symbol_table);
   if (!ok)
     return -1;
 
-  ok = resolve_symbols(program, symbol_table);
-  if (!ok)
-    return -1;
-
-
-  std::string output_filename {argv[2]};
+  std::cerr << "output: " << argv[argc - 1] << '\n';
+  std::string output_filename {argv[argc - 1]};
   std::ofstream out {output_filename, std::ios::binary};
   if (!out.is_open()) {
     std::cerr << "failed to open " << output_filename << '\n';
     return -1;
   }
 
-  serialize_program(program, symbol_table, 0x8200, out);
+  serialize_program(program, symbol_table, out);
 
   out.close();
   return 0;
diff --git a/parser.cc b/parser.cc
index 2be279b..2acb3f9 100644
--- a/parser.cc
+++ b/parser.cc
@@ -8,6 +8,7 @@
 #include "addressing_mode.hh"
 #include "fromstring.hh"
 #include "isa.hh"
+#include "symbol.hh"
 
 static bool tokenize(std::string_view buf, std::function<bool(std::string_view, ssize_t, ssize_t)> cb)
 {
@@ -68,30 +69,14 @@ namespace parser {
   };
 }
 
-using symbol_strings_t = std::unordered_map<std::string_view, size_t>;
-
 namespace parser {
 
-bool parse(std::string_view buf, assembler::program_t& program)
+bool parse(std::string_view buf, assembler::program_t& program, assembler::symbol_strings_t& symbol_strings)
 {
-  size_t current_symbol = 0;
-  symbol_strings_t ss;
-
   parser::state state = parser::state::label_or_op;
 
-  auto get_symbol = [&](std::string_view s) {
-    auto find = ss.find(s);
-    if (find == ss.end()) {
-      auto insert = ss.insert({s, current_symbol++});
-      assert(insert.second);
-      return (insert.first)->second;
-    } else {
-      return find->second;
-    }
-  };
-
   assembler::instruction_t current_instruction;
-  ssize_t current_row;
+  current_instruction.location = 0xeeee;
 
   bool inside_comment = false;
 
@@ -100,11 +85,11 @@ bool parse(std::string_view buf, assembler::program_t& program)
       switch (state) {
       case parser::state::label_or_op:
       {
-        current_row = row;
+        current_instruction.row = row;
         if (s.back() == ':') {
           std::string_view key = s.substr(0, s.length() - 1);
-          auto symbol = get_symbol(key);
-          std::cerr << "label `" << symbol << "`\n";
+          auto symbol = symbol::get(symbol_strings, key);
+          //std::cerr << "label `" << symbol << "`\n";
           current_instruction.symbol = symbol;
           state = parser::state::op;
           return true;
@@ -121,28 +106,28 @@ bool parse(std::string_view buf, assembler::program_t& program)
       }
       case parser::state::op:
       {
-        assert(row == current_row);
+        assert(row == current_instruction.row);
         auto op_it = fromstring::op().find(s);
         if (op_it == fromstring::op().end()) {
-          std::cerr << "invalid op `" << s << "`\n";
+          std::cerr << row << ',' << col << ": invalid op `" << s << "`\n";
           return false;
         } else {
           current_instruction.op = op_it->second;
-          std::cerr << "ok op `" << static_cast<int>(op_it->second) << "`\n";
+          //std::cerr << row << ": ok op `" << static_cast<int>(op_it->second) << "`\n";
         }
         state = parser::state::mode;
         return true;
       }
       case parser::state::mode:
       {
-        assert(row == current_row);
+        assert(row == current_instruction.row);
         auto mode_it = fromstring::mode().find(s);
         if (mode_it == fromstring::mode().end()) {
-          std::cerr << "invalid mode `" << s << "`\n";
+          std::cerr << row << ',' << col << ": invalid mode `" << s << "`\n";
           return false;
         } else {
           current_instruction.mode = mode_it->second;
-          std::cerr << "ok mode `" << static_cast<int>(mode_it->second) << "`\n";
+          //std::cerr << "ok mode `" << static_cast<int>(mode_it->second) << "`\n";
         }
         state = parser::state::value;
         return true;
@@ -152,14 +137,14 @@ bool parse(std::string_view buf, assembler::program_t& program)
         auto am_it = addressing_mode().find(current_instruction.mode);
         assert(am_it != addressing_mode().end());
         if (am_it->second.len == 0) {
-          std::cerr << "no value expected\n";
+          //std::cerr << row << ',' << col << ": no value expected\n";
           assembler::implied_t i {};
           current_instruction.value = i;
           state = parser::state::comment;
           continue;
         }
 
-        assert(row == current_row);
+        assert(row == current_instruction.row);
 
         auto parse_integer = [](std::string_view s, int base) -> std::optional<ssize_t> {
           std::string value_str {s.data(), s.length()};
@@ -185,52 +170,62 @@ bool parse(std::string_view buf, assembler::program_t& program)
         case '7':
         case '8':
         case '9':
-        case 'A':
-        case 'B':
-        case 'C':
-        case 'D':
-        case 'E':
-        case 'F':
+        case 'a':
+        case 'b':
+        case 'c':
+        case 'd':
+        case 'e':
+        case 'f':
         {
           literal = parse_integer(s, 16);
           if (literal == std::nullopt) {
-            std::cerr << row << ": invalid hex literal\n";
+            std::cerr << row << ',' << col << ": invalid hex literal\n";
           }
           current_instruction.value = as_literal(*literal);
-          std::cerr << "value hex literal `" << *literal << "`\n";
+          //std::cerr << "value hex literal `" << *literal << "`\n";
           break;
         }
-        case 'h':
+        case '%':
+        {
+          literal = parse_integer(s.substr(1, s.length() - 1), 2);
+          if (literal == std::nullopt) {
+            std::cerr << row << ',' << col << ": invalid bin literal\n";
+          }
+          current_instruction.value = as_literal(*literal);
+          //std::cerr << "value bin literal `" << *literal << "`\n";
+          break;
+        }
+        case '$':
         {
           literal = parse_integer(s.substr(1, s.length() - 1), 16);
           if (literal == std::nullopt) {
-            std::cerr << row << ": invalid hex literal\n";
+            std::cerr << row << ',' << col << ": invalid hex literal\n";
           }
           current_instruction.value = as_literal(*literal);
-          std::cerr << "value hex literal `" << *literal << "`\n";
+          //std::cerr << "value hex literal `" << *literal << "`\n";
           break;
         }
-        case 'd':
+        case 'i':
         {
           literal = parse_integer(s.substr(1, s.length() - 1), 10);
           if (literal == std::nullopt) {
-            std::cerr << row << ": invalid dec literal\n";
+            std::cerr << row << ',' << col << ": invalid dec literal\n";
             return false;
           }
           current_instruction.value = as_literal(*literal);
-          std::cerr << "value dec literal `" << *literal << "`\n";
+          //std::cerr << "value dec literal `" << *literal << "`\n";
           break;
         }
         case ':':
         {
           std::string_view key = s.substr(1, s.length() - 1);
-          assembler::reference_t reference = { get_symbol(key) };
+          assembler::reference_t reference = { symbol::get(symbol_strings, key) };
           current_instruction.value = reference;
-          std::cerr << "value reference `" << reference.symbol << "`\n";
+          //std::cerr << "value reference `" << reference.symbol << "`\n";
           break;
         }
         default:
-          std::cerr << row << ": invalid base\n";
+          std::cerr << row << ',' << col << ": invalid base\n";
           return false;
         }
 
@@ -239,8 +234,8 @@ bool parse(std::string_view buf, assembler::program_t& program)
       }
       case parser::state::comment:
       {
-        if (row != current_row) {
-          std::cerr << "push " << (int)current_instruction.op << '\n';
+        if (row != current_instruction.row) {
+          //std::cerr << "push " << (int)current_instruction.op << '\n';
           inside_comment = false;
           program.push_back(current_instruction);
           state = parser::state::label_or_op;
@@ -253,13 +248,13 @@ bool parse(std::string_view buf, assembler::program_t& program)
         } else if (inside_comment) {
           return true;
         } else {
-          std::cerr << row << ": expected comment\n";
+          std::cerr << row << ',' << col << ": expected comment\n";
           return false;
         }
       }
       case parser::state::just_comment:
       {
-        if (row != current_row) {
+        if (row != current_instruction.row) {
           inside_comment = false;
           state = parser::state::label_or_op;
           continue;
@@ -271,7 +266,7 @@ bool parse(std::string_view buf, assembler::program_t& program)
         } else if (inside_comment) {
           return true;
         } else {
-          std::cerr << "expected comment\n";
+          std::cerr << row << ',' << col << ": expected comment\n";
           return false;
         }
       }
diff --git a/parser.hh b/parser.hh
index e7abcd3..a4e61de 100644
--- a/parser.hh
+++ b/parser.hh
@@ -5,5 +5,5 @@
 #include "assembler.hh"
 
 namespace parser {
-  bool parse(std::string_view buf, assembler::program_t& program);
+  bool parse(std::string_view buf, assembler::program_t& program, assembler::symbol_strings_t& symbol_strings);
 }
diff --git a/symbol.cc b/symbol.cc
new file mode 100644
index 0000000..2626ed8
--- /dev/null
+++ b/symbol.cc
@@ -0,0 +1,63 @@
+#include <string_view>
+#include <cassert>
+#include <iostream>
+
+#include "assembler.hh"
+#include "addressing_mode.hh"
+
+namespace symbol {
+
+size_t get(assembler::symbol_strings_t& symbol_strings, std::string_view s) {
+  std::string key {s};
+  auto find = symbol_strings.map.find(key);
+  if (find == symbol_strings.map.end()) {
+    std::cerr << "get new: " << s << ' ' << symbol_strings.current_symbol << '\n';
+    auto insert = symbol_strings.map.insert({key, symbol_strings.current_symbol++});
+    assert(insert.second);
+    return (insert.first)->second;
+  } else {
+    return find->second;
+  }
+}
+
+bool resolve(size_t link_location, assembler::program_t& program, assembler::symbol_table_t& symbol_table)
+{
+  size_t offset = link_location;
+
+  for (auto prog_it = program.begin(); prog_it != program.end(); prog_it++) {
+    if (std::holds_alternative<assembler::instruction_t>(*prog_it)) {
+      auto& ins = std::get<assembler::instruction_t>(*prog_it);
+      ins.location = offset;
+      if (ins.symbol != std::nullopt) {
+        auto [_, ok] = symbol_table.insert({*(ins.symbol), offset});
+        if (!ok) {
+          std::cerr << ins.row << ": duplicate symbol\n";
+          return false;
+        }
+      }
+
+      auto am_it = addressing_mode().find(ins.mode);
+      assert (am_it != addressing_mode().end());
+      offset += 1 + am_it->second.len;
+    } else if (std::holds_alternative<assembler::blob_t>(*prog_it)) {
+      auto& blob = std::get<assembler::blob_t>(*prog_it);
+      blob.location = offset + 4;
+      auto [_1, ok1] = symbol_table.insert({blob.symbol.start, offset});
+      auto [_2, ok2] = symbol_table.insert({blob.symbol.start_l, (offset >> 0) & 0xff});
+      auto [_3, ok3] = symbol_table.insert({blob.symbol.start_h, (offset >> 8) & 0xff});
+      auto [_4, ok4] = symbol_table.insert({blob.symbol.size_l, (blob.buf->size() >> 0) & 0xff});
+      auto [_5, ok5] = symbol_table.insert({blob.symbol.size_h, (blob.buf->size() >> 8) & 0xff});
+      if (!ok1 || !ok2 || !ok3 || !ok4 || !ok5) {
+        std::cerr << "duplicate blob symbol\n";
+        return false;
+      }
+      offset += 4 + blob.buf->size();
+    } else {
+      assert(false);
+    }
+  }
+
+  return true;
+}
+
+}
diff --git a/symbol.hh b/symbol.hh
new file mode 100644
index 0000000..66c7a66
--- /dev/null
+++ b/symbol.hh
@@ -0,0 +1,11 @@
+#include <string_view>
+
+#include "assembler.hh"
+
+namespace symbol {
+
+size_t get(assembler::symbol_strings_t& symbol_strings, std::string_view s);
+
+bool resolve(size_t link_location, assembler::program_t& program, assembler::symbol_table_t& symbol_table);
+
+}
diff --git a/tostring.cc b/tostring.cc
index b5e84a4..17de7af 100644
--- a/tostring.cc
+++ b/tostring.cc
@@ -1,127 +1,133 @@
-#include <map>
+#include <unordered_map>
 #include <string>
 
-#include "instruction.hh"
+#include "isa.hh"
 #include "mneumonic.hh"
 
 namespace tostring {
-  const std::unordered_map<op_t, std::string_view> op {
-    {op::ADC, mneumonic::op::ADC},
-    {op::AND, mneumonic::op::AND},
-    {op::ASL, mneumonic::op::ASL},
-    {op::BBR0, mneumonic::op::BBR0},
-    {op::BBR1, mneumonic::op::BBR1},
-    {op::BBR2, mneumonic::op::BBR2},
-    {op::BBR3, mneumonic::op::BBR3},
-    {op::BBR4, mneumonic::op::BBR4},
-    {op::BBR5, mneumonic::op::BBR5},
-    {op::BBR6, mneumonic::op::BBR6},
-    {op::BBR7, mneumonic::op::BBR7},
-    {op::BBS0, mneumonic::op::BBS0},
-    {op::BBS1, mneumonic::op::BBS1},
-    {op::BBS2, mneumonic::op::BBS2},
-    {op::BBS3, mneumonic::op::BBS3},
-    {op::BBS4, mneumonic::op::BBS4},
-    {op::BBS5, mneumonic::op::BBS5},
-    {op::BBS6, mneumonic::op::BBS6},
-    {op::BBS7, mneumonic::op::BBS7},
-    {op::BCC, mneumonic::op::BCC},
-    {op::BCS, mneumonic::op::BCS},
-    {op::BEQ, mneumonic::op::BEQ},
-    {op::BIT, mneumonic::op::BIT},
-    {op::BMI, mneumonic::op::BMI},
-    {op::BNE, mneumonic::op::BNE},
-    {op::BPL, mneumonic::op::BPL},
-    {op::BRA, mneumonic::op::BRA},
-    {op::BRK, mneumonic::op::BRK},
-    {op::BVC, mneumonic::op::BVC},
-    {op::BVS, mneumonic::op::BVS},
-    {op::CLC, mneumonic::op::CLC},
-    {op::CLD, mneumonic::op::CLD},
-    {op::CLI, mneumonic::op::CLI},
-    {op::CLV, mneumonic::op::CLV},
-    {op::CMP, mneumonic::op::CMP},
-    {op::CPX, mneumonic::op::CPX},
-    {op::CPY, mneumonic::op::CPY},
-    {op::DEC, mneumonic::op::DEC},
-    {op::DEX, mneumonic::op::DEX},
-    {op::DEY, mneumonic::op::DEY},
-    {op::EOR, mneumonic::op::EOR},
-    {op::INC, mneumonic::op::INC},
-    {op::INX, mneumonic::op::INX},
-    {op::INY, mneumonic::op::INY},
-    {op::JMP, mneumonic::op::JMP},
-    {op::JSR, mneumonic::op::JSR},
-    {op::LDA, mneumonic::op::LDA},
-    {op::LDX, mneumonic::op::LDX},
-    {op::LDY, mneumonic::op::LDY},
-    {op::LSR, mneumonic::op::LSR},
-    {op::NOP, mneumonic::op::NOP},
-    {op::ORA, mneumonic::op::ORA},
-    {op::PHA, mneumonic::op::PHA},
-    {op::PHP, mneumonic::op::PHP},
-    {op::PHX, mneumonic::op::PHX},
-    {op::PHY, mneumonic::op::PHY},
-    {op::PLA, mneumonic::op::PLA},
-    {op::PLP, mneumonic::op::PLP},
-    {op::PLX, mneumonic::op::PLX},
-    {op::PLY, mneumonic::op::PLY},
-    {op::RMB0, mneumonic::op::RMB0},
-    {op::RMB1, mneumonic::op::RMB1},
-    {op::RMB2, mneumonic::op::RMB2},
-    {op::RMB3, mneumonic::op::RMB3},
-    {op::RMB4, mneumonic::op::RMB4},
-    {op::RMB5, mneumonic::op::RMB5},
-    {op::RMB6, mneumonic::op::RMB6},
-    {op::RMB7, mneumonic::op::RMB7},
-    {op::ROL, mneumonic::op::ROL},
-    {op::ROR, mneumonic::op::ROR},
-    {op::RTI, mneumonic::op::RTI},
-    {op::RTS, mneumonic::op::RTS},
-    {op::SBC, mneumonic::op::SBC},
-    {op::SEC, mneumonic::op::SEC},
-    {op::SED, mneumonic::op::SED},
-    {op::SEI, mneumonic::op::SEI},
-    {op::SMB0, mneumonic::op::SMB0},
-    {op::SMB1, mneumonic::op::SMB1},
-    {op::SMB2, mneumonic::op::SMB2},
-    {op::SMB3, mneumonic::op::SMB3},
-    {op::SMB4, mneumonic::op::SMB4},
-    {op::SMB5, mneumonic::op::SMB5},
-    {op::SMB6, mneumonic::op::SMB6},
-    {op::SMB7, mneumonic::op::SMB7},
-    {op::STA, mneumonic::op::STA},
-    {op::STP, mneumonic::op::STP},
-    {op::STX, mneumonic::op::STX},
-    {op::STY, mneumonic::op::STY},
-    {op::STZ, mneumonic::op::STZ},
-    {op::TAX, mneumonic::op::TAX},
-    {op::TAY, mneumonic::op::TAY},
-    {op::TRB, mneumonic::op::TRB},
-    {op::TSB, mneumonic::op::TSB},
-    {op::TSX, mneumonic::op::TSX},
-    {op::TXA, mneumonic::op::TXA},
-    {op::TXS, mneumonic::op::TXS},
-    {op::TYA, mneumonic::op::TYA},
-    {op::WAI, mneumonic::op::WAI},
-  };
+  const std::unordered_map<isa::op, std::string_view>& op() {
+    static const std::unordered_map<isa::op, std::string_view> _ = {
+      {isa::op::ADC, mneumonic::op::ADC},
+      {isa::op::AND, mneumonic::op::AND},
+      {isa::op::ASL, mneumonic::op::ASL},
+      {isa::op::BBR0, mneumonic::op::BBR0},
+      {isa::op::BBR1, mneumonic::op::BBR1},
+      {isa::op::BBR2, mneumonic::op::BBR2},
+      {isa::op::BBR3, mneumonic::op::BBR3},
+      {isa::op::BBR4, mneumonic::op::BBR4},
+      {isa::op::BBR5, mneumonic::op::BBR5},
+      {isa::op::BBR6, mneumonic::op::BBR6},
+      {isa::op::BBR7, mneumonic::op::BBR7},
+      {isa::op::BBS0, mneumonic::op::BBS0},
+      {isa::op::BBS1, mneumonic::op::BBS1},
+      {isa::op::BBS2, mneumonic::op::BBS2},
+      {isa::op::BBS3, mneumonic::op::BBS3},
+      {isa::op::BBS4, mneumonic::op::BBS4},
+      {isa::op::BBS5, mneumonic::op::BBS5},
+      {isa::op::BBS6, mneumonic::op::BBS6},
+      {isa::op::BBS7, mneumonic::op::BBS7},
+      {isa::op::BCC, mneumonic::op::BCC},
+      {isa::op::BCS, mneumonic::op::BCS},
+      {isa::op::BEQ, mneumonic::op::BEQ},
+      {isa::op::BIT, mneumonic::op::BIT},
+      {isa::op::BMI, mneumonic::op::BMI},
+      {isa::op::BNE, mneumonic::op::BNE},
+      {isa::op::BPL, mneumonic::op::BPL},
+      {isa::op::BRA, mneumonic::op::BRA},
+      {isa::op::BRK, mneumonic::op::BRK},
+      {isa::op::BVC, mneumonic::op::BVC},
+      {isa::op::BVS, mneumonic::op::BVS},
+      {isa::op::CLC, mneumonic::op::CLC},
+      {isa::op::CLD, mneumonic::op::CLD},
+      {isa::op::CLI, mneumonic::op::CLI},
+      {isa::op::CLV, mneumonic::op::CLV},
+      {isa::op::CMP, mneumonic::op::CMP},
+      {isa::op::CPX, mneumonic::op::CPX},
+      {isa::op::CPY, mneumonic::op::CPY},
+      {isa::op::DEC, mneumonic::op::DEC},
+      {isa::op::DEX, mneumonic::op::DEX},
+      {isa::op::DEY, mneumonic::op::DEY},
+      {isa::op::EOR, mneumonic::op::EOR},
+      {isa::op::INC, mneumonic::op::INC},
+      {isa::op::INX, mneumonic::op::INX},
+      {isa::op::INY, mneumonic::op::INY},
+      {isa::op::JMP, mneumonic::op::JMP},
+      {isa::op::JSR, mneumonic::op::JSR},
+      {isa::op::LDA, mneumonic::op::LDA},
+      {isa::op::LDX, mneumonic::op::LDX},
+      {isa::op::LDY, mneumonic::op::LDY},
+      {isa::op::LSR, mneumonic::op::LSR},
+      {isa::op::NOP, mneumonic::op::NOP},
+      {isa::op::ORA, mneumonic::op::ORA},
+      {isa::op::PHA, mneumonic::op::PHA},
+      {isa::op::PHP, mneumonic::op::PHP},
+      {isa::op::PHX, mneumonic::op::PHX},
+      {isa::op::PHY, mneumonic::op::PHY},
+      {isa::op::PLA, mneumonic::op::PLA},
+      {isa::op::PLP, mneumonic::op::PLP},
+      {isa::op::PLX, mneumonic::op::PLX},
+      {isa::op::PLY, mneumonic::op::PLY},
+      {isa::op::RMB0, mneumonic::op::RMB0},
+      {isa::op::RMB1, mneumonic::op::RMB1},
+      {isa::op::RMB2, mneumonic::op::RMB2},
+      {isa::op::RMB3, mneumonic::op::RMB3},
+      {isa::op::RMB4, mneumonic::op::RMB4},
+      {isa::op::RMB5, mneumonic::op::RMB5},
+      {isa::op::RMB6, mneumonic::op::RMB6},
+      {isa::op::RMB7, mneumonic::op::RMB7},
+      {isa::op::ROL, mneumonic::op::ROL},
+      {isa::op::ROR, mneumonic::op::ROR},
+      {isa::op::RTI, mneumonic::op::RTI},
+      {isa::op::RTS, mneumonic::op::RTS},
+      {isa::op::SBC, mneumonic::op::SBC},
+      {isa::op::SEC, mneumonic::op::SEC},
+      {isa::op::SED, mneumonic::op::SED},
+      {isa::op::SEI, mneumonic::op::SEI},
+      {isa::op::SMB0, mneumonic::op::SMB0},
+      {isa::op::SMB1, mneumonic::op::SMB1},
+      {isa::op::SMB2, mneumonic::op::SMB2},
+      {isa::op::SMB3, mneumonic::op::SMB3},
+      {isa::op::SMB4, mneumonic::op::SMB4},
+      {isa::op::SMB5, mneumonic::op::SMB5},
+      {isa::op::SMB6, mneumonic::op::SMB6},
+      {isa::op::SMB7, mneumonic::op::SMB7},
+      {isa::op::STA, mneumonic::op::STA},
+      {isa::op::STP, mneumonic::op::STP},
+      {isa::op::STX, mneumonic::op::STX},
+      {isa::op::STY, mneumonic::op::STY},
+      {isa::op::STZ, mneumonic::op::STZ},
+      {isa::op::TAX, mneumonic::op::TAX},
+      {isa::op::TAY, mneumonic::op::TAY},
+      {isa::op::TRB, mneumonic::op::TRB},
+      {isa::op::TSB, mneumonic::op::TSB},
+      {isa::op::TSX, mneumonic::op::TSX},
+      {isa::op::TXA, mneumonic::op::TXA},
+      {isa::op::TXS, mneumonic::op::TXS},
+      {isa::op::TYA, mneumonic::op::TYA},
+      {isa::op::WAI, mneumonic::op::WAI},
+    };
+    return _;
+  }
 
-  const std::unordered_map<amode_t, std::string_view> mode {
-    {mode::A, mneumonic::mode::A},
-    {mode::AII, mneumonic::mode::AII},
-    {mode::AIX, mneumonic::mode::AIX},
-    {mode::AIY, mneumonic::mode::AIY},
-    {mode::AI, mneumonic::mode::AI},
-    {mode::ACC, mneumonic::mode::ACC},
-    {mode::IMM, mneumonic::mode::IMM},
-    {mode::I, mneumonic::mode::I},
-    {mode::R, mneumonic::mode::R},
-    {mode::S, mneumonic::mode::S},
-    {mode::ZP, mneumonic::mode::ZP},
-    {mode::ZPII, mneumonic::mode::ZPII},
-    {mode::ZPX, mneumonic::mode::ZPX},
-    {mode::ZPY, mneumonic::mode::ZPY},
-    {mode::ZPI, mneumonic::mode::ZPI},
-    {mode::ZPIY, mneumonic::mode::ZPIY},
-  };
+  const std::unordered_map<isa::mode, std::string_view>& mode() {
+    static const std::unordered_map<isa::mode, std::string_view> _ = {
+      {isa::mode::A, mneumonic::mode::A},
+      {isa::mode::AII, mneumonic::mode::AII},
+      {isa::mode::AIX, mneumonic::mode::AIX},
+      {isa::mode::AIY, mneumonic::mode::AIY},
+      {isa::mode::AI, mneumonic::mode::AI},
+      {isa::mode::ACC, mneumonic::mode::ACC},
+      {isa::mode::IMM, mneumonic::mode::IMM},
+      {isa::mode::I, mneumonic::mode::I},
+      {isa::mode::R, mneumonic::mode::R},
+      {isa::mode::S, mneumonic::mode::S},
+      {isa::mode::ZP, mneumonic::mode::ZP},
+      {isa::mode::ZPII, mneumonic::mode::ZPII},
+      {isa::mode::ZPX, mneumonic::mode::ZPX},
+      {isa::mode::ZPY, mneumonic::mode::ZPY},
+      {isa::mode::ZPI, mneumonic::mode::ZPI},
+      {isa::mode::ZPIY, mneumonic::mode::ZPIY},
+    };
+    return _;
+  }
 }
diff --git a/tostring.hh b/tostring.hh
index a7200c0..2344264 100644
--- a/tostring.hh
+++ b/tostring.hh
@@ -5,7 +5,6 @@
 #include "mneumonic.hh"
 
 namespace tostring {
-  extern const std::unordered_map<op_t, std::string_view> op;
-
-  extern const std::unordered_map<amode_t, std::string_view> mode;
+  const std::unordered_map<isa::op, std::string_view>& op();
+  const std::unordered_map<isa::mode, std::string_view>& mode();
 }