diff --git a/.forgejo/workflows/test.yml b/.forgejo/workflows/test.yml
index 0ce7564..735fab5 100644
--- a/.forgejo/workflows/test.yml
+++ b/.forgejo/workflows/test.yml
@@ -79,4 +79,6 @@ jobs:
         run:  cargo test util
       - name: test garbage collection
         run:  cargo test heap
+      - name: test instruction set implementation
+        run:  cargo test isa_
 
diff --git a/hyphae/src/heap.rs b/hyphae/src/heap.rs
index 6d79215..75ce680 100644
--- a/hyphae/src/heap.rs
+++ b/hyphae/src/heap.rs
@@ -21,6 +21,7 @@ use core::ptr::NonNull;
 use alloc::rc::Rc;
 use alloc::vec::Vec;
 use alloc::boxed::Box;
+use alloc::fmt::Debug;
 use alloc::string::String;
 
 use organelle::Number;
@@ -112,6 +113,18 @@ impl<T> Clone for Gc<T> {
     }
 }
 
+impl<T: Debug> Debug for Gc<T> {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.debug_struct("GarbageCollected")
+            .field("refs", &unsafe {
+                Rc::strong_count(self.0.as_ref())
+            })
+            .field("inner", 
+                (*(unsafe { self.0.as_ref() })).as_ref())
+            .finish()
+    }
+}
+
 impl<T> Drop for Gc<T> {
     fn drop(&mut self) {
         unsafe {
@@ -132,7 +145,7 @@ impl<T: Clone> Gc<T> {
     }
 }
 
-#[derive(PartialEq)]
+#[derive(PartialEq, Debug)]
 pub enum Datum {
     Number(Number),
     Bool(bool),
@@ -168,7 +181,7 @@ impl Clone for Datum {
     }
 }
 
-#[derive(Clone, PartialEq)]
+#[derive(Clone, PartialEq, Debug)]
 pub struct Cons(pub Option<Gc<Datum>>, pub Option<Gc<Datum>>);
 
 impl Cons {
diff --git a/hyphae/src/stackstack.rs b/hyphae/src/stackstack.rs
index 6a403fb..1a7adbf 100644
--- a/hyphae/src/stackstack.rs
+++ b/hyphae/src/stackstack.rs
@@ -278,4 +278,12 @@ mod tests {
         assert_eq!(g[1], 1);
         assert_eq!(g[2], 0);
     }
+
+    #[test]
+    fn test_stack_idx_zero() {
+        let mut g = StackStack::<i8>::new();
+        g.add_stack();
+        g.push_current_stack(2);
+        assert_eq!(g[0], 2);
+    }
 }
diff --git a/hyphae/src/vm.rs b/hyphae/src/vm.rs
index a181055..378ab23 100644
--- a/hyphae/src/vm.rs
+++ b/hyphae/src/vm.rs
@@ -62,7 +62,7 @@ pub struct VM {
 impl From<Program> for VM {
     fn from(value: Program) -> Self {
         VM{
-            stack: StackStack::new(),
+            stack: StackStack::<Gc<Datum>>::new(),
             symtab: QuickMap::new(),
             prog: value,
             traps: vec![],
@@ -143,8 +143,6 @@ impl VM {
 
     #[inline(always)]
     fn execute_instruction(&mut self) {
-        let instr = &self.prog.0[self.ictr].clone();
-
         macro_rules! e {
             ( $err:expr ) => {
                 {
@@ -156,6 +154,11 @@ impl VM {
             }
         }
 
+        if self.ictr > self.prog.0.len() {
+            e!("attempt to execute out of bounds instruction");
+        }
+        let instr = &self.prog.0[self.ictr].clone();
+
         // get or set according to addressing mode
         macro_rules! access {
             ( $oper:expr ) => {
@@ -244,7 +247,7 @@ impl VM {
                     e!("illegal argument to BOUND instruction");
                 };
                 let tag = unsafe { str::from_utf8_unchecked(tag) };
-                self.symtab.contains_key(tag);
+                self.expr = Datum::Bool(self.symtab.contains_key(tag)).into();
             },
 
             // stack ops
@@ -402,7 +405,7 @@ impl VM {
             },
 
             i::CONST => access!(&instr.1[0], {
-                let Operand(Address::Numer, num) = instr.1[0] else {
+                let Operand(Address::Numer, num) = instr.1[1] else {
                     e!("illegal argument to CONST instruction");
                 };
 
@@ -588,123 +591,13 @@ impl VM {
 
 #[cfg(test)]
 mod tests {
-    use core::array;
     use super::*;
-    use crate::instr;
-
-    const ISA_TESTS: [Option<Vec<(VM, TestResult)>>; instr::TOTAL_INSTRUCTIONS] = [
-        // TRAP
-        None,
-        // BIND
-        None,
-        // UNBIND
-        None,
-        // BOUND
-        None,
-        // PUSH
-        None,
-        // POP
-        None,
-        // ENTER
-        None,
-        // EXIT
-        None,
-        // LOAD
-        None,
-        // DUPL
-        None,
-        // CLEAR
-        None,
-        // NOP
-        None,
-        // HALT
-        None,
-        // PANIC
-        None,
-        // JMP
-        None,
-        // JMPIF
-        None,
-        // EQ
-        None,
-        // LT
-        None,
-        // GT
-        None,
-        // LTE
-        None,
-        // GTE
-        None,
-        // BOOL_NOT
-        None,
-        // BOOL_AND
-        None,
-        // BOOL_OR
-        None,
-        // BYTE_AND
-        None,
-        // BYTE_OR
-        None,
-        // XOR
-        None,
-        // BYTE_NOT
-        None,
-        // ADD
-        None,
-        // SUB
-        None,
-        // MUL
-        None,
-        // FDIV
-        None,
-        // IDIV
-        None,
-        // POW
-        None,
-        // MODULO
-        None,
-        // REM
-        None,
-        // INC
-        None,
-        // DEC
-        None,
-        // CTON
-        None,
-        // NTOC
-        None,
-        // NTOI
-        None,
-        // NTOE
-        None,
-        // CONST
-        None,
-        // MKVEC
-        None,
-        // MKBVEC
-        None,
-        // INDEX
-        None,
-        // LENGTH
-        None,
-        // SUBSL
-        None,
-        // INSER
-        None,
-        // CONS
-        None,
-        // CAR
-        None,
-        // CDR
-        None,
-        // CONCAT
-        None,
-        // S_APPEND
-        None,
-    ];
+    use crate::instr as i;
+    use crate::util::{Program, Instruction, Operand};
+    use core::ops::Deref;
 
     fn has_stack(state: &VM, idx: usize, target: Gc<Datum>) -> bool {
-        *(state.stack[idx]) == *target
+        state.stack[idx].deref() == target.deref()
     }
 
     fn has_sym(state: &VM, sym: &str, operand: Option<Operand>) -> bool {
@@ -723,6 +616,8 @@ mod tests {
 
     impl TestResult {
         fn chk_expr(&self, state: &VM) -> bool {
+            print!("expecting expr: {:?}\n", self.expr);
+            print!("has expr: {:?}\n", state.expr.deref());
             self.expr.is_none() || *(state.expr) == *(self.expr.clone().unwrap())
         }
 
@@ -740,6 +635,8 @@ mod tests {
         fn chk_stack(&self, state: &VM) -> bool {
             for i in &self.stack {
                 if !has_stack(&state, i.0, i.1.clone()) {
+                    print!("expected stack to have {:?} at {}\n", *i.1, i.0);
+                    print!("instead has {:?}", state.stack[i.0].deref());
                     return false
                 }
             }
@@ -749,13 +646,15 @@ mod tests {
         fn chk_syms(&self, state: &VM) -> bool {
             for i in &self.syms {
                 if !has_sym(&state, i.0, i.1.clone()) {
+                    print!("expected symbol {} == {:?}\n", i.0, i.1.clone());
+                    print!("instead has {:?}\n", state.symtab.get(&i.0.to_owned()));
                     return false
                 }
             }
             true
         }
 
-        fn test_passes(&self, state: VM) -> bool {
+        fn test_passes(&self, state: &VM) -> bool {
             (self.expr.is_none()   || self.chk_expr(&state))  &&
             (self.stack.is_empty() || self.chk_stack(&state)) &&
             (self.syms.is_empty()  || self.chk_syms(&state))  &&
@@ -764,18 +663,377 @@ mod tests {
     }
 
     #[test]
-    fn run_isa_tests() {
-        for i in &ISA_TESTS.to_vec() {
-            let Some(test_case) = i else {
-                assert!(false); // dont let untested instructions happen
-                return
-            };
+    fn isa_trap_tests() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::TRAP, vec![Operand(Address::Numer, 0)])
+        ])).with_traps(Some(vec![
+            Arc::from(|state: &mut VM| {
+                state.expr = Datum::Bool(true).into()
+            })
+        ])).to_owned();
 
-            for i in test_case {
-                let (mut vm, result) = (i.0.clone(), i.1.clone());
-                vm.run_program();
-                assert!(result.test_passes(vm));
-            }
-        }
+        let case = TestResult{
+            expr: Some(Datum::Bool(true).into()),
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
     }
+
+    #[test]
+    fn isa_symtable_tests() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::BIND, vec![Operand(Address::Stack, 1),
+                                      Operand(Address::Stack, 0)]),
+        ])).with_stack(Some({
+            let mut i = StackStack::<Gc<Datum>>::new();
+            i.push_current_stack(Datum::String("test".into()).into());
+            i.push_current_stack(Datum::String("value".into()).into());
+            i
+       })).to_owned();
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![
+                (1, Datum::String("test".into()).into()),
+                (0, Datum::String("value".into()).into()),
+            ],
+            syms: vec![("test", Some(Operand(Address::Stack, 0)))],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::BIND, vec![Operand(Address::Stack, 1),
+                                      Operand(Address::Stack, 0)]),
+            Instruction(i::BOUND, vec![Operand(Address::Stack, 1)])
+        ])).with_stack(Some({
+            let mut i = StackStack::<Gc<Datum>>::new();
+            i.push_current_stack(Datum::String("test".into()).into());
+            i.push_current_stack(Datum::String("value".into()).into());
+            i
+        })).to_owned();
+
+        let case = TestResult{
+            expr: Some(Datum::Bool(true).into()),
+            stack: vec![
+                (1, Datum::String("test".into()).into()),
+                (0, Datum::String("value".into()).into()),
+            ],
+            syms: vec![("test", Some(Operand(Address::Stack, 0)))],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::BIND, vec![Operand(Address::Stack, 1),
+                                      Operand(Address::Stack, 0)]),
+            Instruction(i::UNBIND, vec![Operand(Address::Stack, 1)])
+        ])).with_stack(Some({
+            let mut i = StackStack::<Gc<Datum>>::new();
+            i.push_current_stack(Datum::String("test".into()).into());
+            i.push_current_stack(Datum::String("value".into()).into());
+            i
+        })).to_owned();
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![
+                (1, Datum::String("test".into()).into()),
+                (0, Datum::String("value".into()).into()),
+            ],
+            syms: vec![("test", None)],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+    }
+
+    #[test]
+    fn isa_stack_tests() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)])
+        ]));
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![
+                (0, Datum::Number(Number::Fra(Fraction(4, 1))).into())
+            ],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+       let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 5)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+            Instruction(i::POP,   vec![])
+        ]));
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![
+                (0, Datum::Number(Number::Fra(Fraction(4, 1))).into())
+            ],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+            Instruction(i::ENTER, vec![]),
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 5)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+        ]));
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![
+                (1, Datum::Number(Number::Fra(Fraction(4, 1))).into()),
+                (0, Datum::Number(Number::Fra(Fraction(5, 1))).into())
+            ],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+            Instruction(i::ENTER, vec![]),
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 5)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 5)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Expr,  0)]),
+            Instruction(i::EXIT,  vec![]),
+        ]));
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![
+                (0, Datum::Number(Number::Fra(Fraction(4, 1))).into()),
+            ],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+    }
+
+    #[test]
+    fn isa_load_dupl_clear() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr, 0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::LOAD,  vec![Operand(Address::Expr, 0),
+                                       Operand(Address::Oper1, 0)]),
+            Instruction(i::DUPL,  vec![Operand(Address::Expr, 0),
+                                       Operand(Address::Oper2, 0)]),
+            Instruction(i::INC,   vec![Operand(Address::Oper2, 0)]),
+            Instruction(i::CLEAR, vec![Operand(Address::Expr, 0)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Oper1, 0)]),
+            Instruction(i::PUSH,  vec![Operand(Address::Oper2, 0)]),
+        ]));
+
+        let case = TestResult{
+            expr: Some(Datum::None.into()),
+            stack: vec![
+                (1, Datum::Number(Number::Fra(Fraction(4, 1))).into()),
+                (0, Datum::Number(Number::Fra(Fraction(5, 1))).into())
+            ],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+    }
+
+    #[test]
+    fn isa_nop_halt_panic() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::NOP, vec![])
+        ]));
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::HALT, vec![]),
+            Instruction(i::PUSH, vec![Operand(Address::Numer, 1)])
+        ]));
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::PANIC, vec![Operand(Address::Stack, 0)])
+        ])).with_stack({
+            let mut i = StackStack::<Gc<Datum>>::new();
+            i.push_current_stack(Datum::String("testerr".into()).into());
+            Some(i)
+        }).to_owned();
+
+        let case = TestResult{
+            expr: None,
+            stack: vec![],
+            syms: vec![],
+            errr: Some("testerr"),
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+    }
+
+    #[test]
+    fn isa_inc_dec() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::INC,   vec![Operand(Address::Expr,  0)]),
+        ]));
+
+        let case = TestResult{
+            expr: Some(Datum::Number(Number::Fra(Fraction(5, 1))).into()),
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 4)]),
+            Instruction(i::DEC,   vec![Operand(Address::Expr,  0)]),
+        ]));
+
+        let case = TestResult{
+            expr: Some(Datum::Number(Number::Fra(Fraction(3, 1))).into()),
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+    }
+
+    #[test]
+    fn isa_jmp_jmpif() {
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::JMP,   vec![Operand(Address::Instr, 2)]),
+            Instruction(i::HALT,  vec![]),
+            Instruction(i::CONST, vec![Operand(Address::Expr, 0),
+                                       Operand(Address::Numer, 3)]),
+        ]));
+
+        let case = TestResult{
+            expr: Some(Datum::Number(Number::Fra(Fraction(3, 1))).into()),
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::LOAD,  vec![Operand(Address::Stack, 0),
+                                       Operand(Address::Expr,  0)]),
+            Instruction(i::JMPIF, vec![Operand(Address::Instr, 3)]),
+            Instruction(i::HALT,  vec![]),
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 3)]),
+        ])).with_stack({
+            let mut i = StackStack::new();
+            i.push_current_stack(Datum::Bool(true).into());
+            Some(i)
+        }).to_owned();
+
+        let case = TestResult{
+            expr: Some(Datum::Number(Number::Fra(Fraction(3, 1))).into()),
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+
+        let mut vm = VM::from(Program(vec![
+            Instruction(i::LOAD,  vec![Operand(Address::Stack, 0),
+                                       Operand(Address::Expr,  0)]),
+            Instruction(i::JMPIF, vec![Operand(Address::Instr, 3)]),
+            Instruction(i::HALT,  vec![]),
+            Instruction(i::CONST, vec![Operand(Address::Expr,  0),
+                                       Operand(Address::Numer, 3)]),
+        ])).with_stack({
+            let mut i = StackStack::new();
+            i.push_current_stack(Datum::Bool(false).into());
+            Some(i)
+        }).to_owned();
+
+        let case = TestResult{
+            expr: Some(Datum::None.into()),
+            stack: vec![],
+            syms: vec![],
+            errr: None,
+        };
+
+        vm.run_program();
+        assert!(case.test_passes(&vm));
+    }
+
+    // TODO NTOI, NTOE, NTOC, CTON
+    // TODO INDEX on V, BV, S, L
+    // TODO LENGTH on V, BV, S, L
+    // TODO SUBSL on V, BV, S, L
+    // TODO INSER on V, BV, S, L
+    // TODO CAR and CDR and CONS
+    // TODO CONCAT and S_APPEND
 }