diff --git a/codeCore/src/prog8/code/core/IMachineDefinition.kt b/codeCore/src/prog8/code/core/IMachineDefinition.kt
index 178ce45c3..82e836cf2 100644
--- a/codeCore/src/prog8/code/core/IMachineDefinition.kt
+++ b/codeCore/src/prog8/code/core/IMachineDefinition.kt
@@ -14,7 +14,7 @@ interface IMachineDefinition {
     val FLOAT_MAX_POSITIVE: Double
     val FLOAT_MEM_SIZE: Int
     val PROGRAM_LOAD_ADDRESS : UInt
-    val PROGRAM_TOP_ADDRESS: UInt
+    val PROGRAM_MEMTOP_ADDRESS: UInt
     val BSSHIGHRAM_START: UInt
     val BSSHIGHRAM_END: UInt
     val BSSGOLDENRAM_START: UInt
diff --git a/codeCore/src/prog8/code/target/atari/AtariMachineDefinition.kt b/codeCore/src/prog8/code/target/atari/AtariMachineDefinition.kt
index 3c4fd9288..2d32a2d22 100644
--- a/codeCore/src/prog8/code/target/atari/AtariMachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/atari/AtariMachineDefinition.kt
@@ -12,7 +12,7 @@ class AtariMachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = -9.999999999e97
     override val FLOAT_MEM_SIZE = 6
     override val PROGRAM_LOAD_ADDRESS = 0x2000u
-    override val PROGRAM_TOP_ADDRESS = 0xffffu  // TODO what's memtop
+    override val PROGRAM_MEMTOP_ADDRESS = 0xffffu  // TODO what's memtop?
 
     override val BSSHIGHRAM_START = 0u    // TODO
     override val BSSHIGHRAM_END = 0u      // TODO
diff --git a/codeCore/src/prog8/code/target/c128/C128MachineDefinition.kt b/codeCore/src/prog8/code/target/c128/C128MachineDefinition.kt
index 8c4d3923b..8636d6733 100644
--- a/codeCore/src/prog8/code/target/c128/C128MachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/c128/C128MachineDefinition.kt
@@ -14,7 +14,7 @@ class C128MachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
     override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
     override val PROGRAM_LOAD_ADDRESS = 0x1c01u
-    override val PROGRAM_TOP_ADDRESS = 0xfeffu
+    override val PROGRAM_MEMTOP_ADDRESS = 0xff00u
 
     override val BSSHIGHRAM_START = 0u    // TODO
     override val BSSHIGHRAM_END = 0u      // TODO
diff --git a/codeCore/src/prog8/code/target/c64/C64MachineDefinition.kt b/codeCore/src/prog8/code/target/c64/C64MachineDefinition.kt
index 6315ef379..83c08aa7c 100644
--- a/codeCore/src/prog8/code/target/c64/C64MachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/c64/C64MachineDefinition.kt
@@ -15,7 +15,7 @@ class C64MachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
     override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
     override val PROGRAM_LOAD_ADDRESS = 0x0801u
-    override val PROGRAM_TOP_ADDRESS = 0xcfe0u      // $9fff  if floats are used
+    override val PROGRAM_MEMTOP_ADDRESS = 0xcfe0u      // $a000  if floats are used
             // note that at $cfe0-$cfff are the 16 'virtual registers' R0-R15
 
     override val BSSHIGHRAM_START = 0xc000u
diff --git a/codeCore/src/prog8/code/target/cx16/CX16MachineDefinition.kt b/codeCore/src/prog8/code/target/cx16/CX16MachineDefinition.kt
index fa72e9099..3c58e6305 100644
--- a/codeCore/src/prog8/code/target/cx16/CX16MachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/cx16/CX16MachineDefinition.kt
@@ -14,7 +14,7 @@ class CX16MachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
     override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
     override val PROGRAM_LOAD_ADDRESS = 0x0801u
-    override val PROGRAM_TOP_ADDRESS = 0x9effu
+    override val PROGRAM_MEMTOP_ADDRESS = 0x9f00u
 
     override val BSSHIGHRAM_START = 0xa000u     // hiram bank 1, 8Kb, assumed to be active
     override val BSSHIGHRAM_END = 0xbfffu       // Rom starts at $c000
diff --git a/codeCore/src/prog8/code/target/neo6502/Neo6502MachineDefinition.kt b/codeCore/src/prog8/code/target/neo6502/Neo6502MachineDefinition.kt
index 90b874ddf..b006968d1 100644
--- a/codeCore/src/prog8/code/target/neo6502/Neo6502MachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/neo6502/Neo6502MachineDefinition.kt
@@ -12,7 +12,7 @@ class Neo6502MachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = -9.999999999e97
     override val FLOAT_MEM_SIZE = 6
     override val PROGRAM_LOAD_ADDRESS = 0x0800u
-    override val PROGRAM_TOP_ADDRESS = 0xfbffu
+    override val PROGRAM_MEMTOP_ADDRESS = 0xfc00u       // kernal starts here
 
     override val BSSHIGHRAM_START = 0u    // TODO
     override val BSSHIGHRAM_END = 0u      // TODO
diff --git a/codeCore/src/prog8/code/target/pet/PETMachineDefinition.kt b/codeCore/src/prog8/code/target/pet/PETMachineDefinition.kt
index b71cda9ef..09302d76d 100644
--- a/codeCore/src/prog8/code/target/pet/PETMachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/pet/PETMachineDefinition.kt
@@ -14,7 +14,7 @@ class PETMachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = Mflpt5.FLOAT_MAX_NEGATIVE
     override val FLOAT_MEM_SIZE = Mflpt5.FLOAT_MEM_SIZE
     override val PROGRAM_LOAD_ADDRESS = 0x0401u
-    override val PROGRAM_TOP_ADDRESS = 0x7fffu
+    override val PROGRAM_MEMTOP_ADDRESS = 0x8000u
 
     override val BSSHIGHRAM_START = 0u
     override val BSSHIGHRAM_END = 0u
diff --git a/codeCore/src/prog8/code/target/virtual/VirtualMachineDefinition.kt b/codeCore/src/prog8/code/target/virtual/VirtualMachineDefinition.kt
index 15cd7bc74..96de9c098 100644
--- a/codeCore/src/prog8/code/target/virtual/VirtualMachineDefinition.kt
+++ b/codeCore/src/prog8/code/target/virtual/VirtualMachineDefinition.kt
@@ -14,7 +14,7 @@ class VirtualMachineDefinition: IMachineDefinition {
     override val FLOAT_MAX_NEGATIVE = -Float.MAX_VALUE.toDouble()
     override val FLOAT_MEM_SIZE = 8             // 64-bits double
     override val PROGRAM_LOAD_ADDRESS = 0u      // not actually used
-    override val PROGRAM_TOP_ADDRESS = 0xffffu  // not actually used
+    override val PROGRAM_MEMTOP_ADDRESS = 0xffffu  // not actually used
 
     override val BSSHIGHRAM_START = 0u          // not actually used
     override val BSSHIGHRAM_END = 0u            // not actually used
diff --git a/codeGenCpu6502/src/prog8/codegen/cpu6502/ProgramAndVarsGen.kt b/codeGenCpu6502/src/prog8/codegen/cpu6502/ProgramAndVarsGen.kt
index 1ae16c7b1..852a31fab 100644
--- a/codeGenCpu6502/src/prog8/codegen/cpu6502/ProgramAndVarsGen.kt
+++ b/codeGenCpu6502/src/prog8/codegen/cpu6502/ProgramAndVarsGen.kt
@@ -287,7 +287,7 @@ internal class ProgramAndVarsGen(
             }
         }
         asmgen.out("  ; memtop check")
-        asmgen.out("  .cerror * > ${options.memtopAddress.toHex()}, \"Program too long by \", * - ${options.memtopAddress.toHex()}, \" bytes, memtop=${options.memtopAddress.toHex()}\"")
+        asmgen.out("  .cerror * >= ${options.memtopAddress.toHex()}, \"Program too long by \", * - ${(options.memtopAddress-1u).toHex()}, \" bytes, memtop=${options.memtopAddress.toHex()}\"")
     }
 
     private fun block2asm(block: PtBlock) {
diff --git a/compiler/src/prog8/compiler/Compiler.kt b/compiler/src/prog8/compiler/Compiler.kt
index ab882c36a..820df9dcb 100644
--- a/compiler/src/prog8/compiler/Compiler.kt
+++ b/compiler/src/prog8/compiler/Compiler.kt
@@ -264,7 +264,7 @@ internal fun determineProgramLoadAddress(program: Program, options: CompilationO
     }
 
     options.loadAddress = loadAddress
-    options.memtopAddress = program.toplevelModule.memtopAddress?.first ?: options.compTarget.machine.PROGRAM_TOP_ADDRESS
+    options.memtopAddress = program.toplevelModule.memtopAddress?.first ?: options.compTarget.machine.PROGRAM_MEMTOP_ADDRESS
 }
 
 
diff --git a/docs/source/syntaxreference.rst b/docs/source/syntaxreference.rst
index bf7dc9215..bd100e1ab 100644
--- a/docs/source/syntaxreference.rst
+++ b/docs/source/syntaxreference.rst
@@ -191,8 +191,8 @@ Directives
 	but with this you can change it to another value. This can be useful for example to 'reserve' a piece
 	of memory at the end of program space where other data such as external library files can be loaded into.
 	This memtop value is used for a check instruction for the assembler to see if the resulting program size
-	exceeds the given memtop address. This value is inclusive, so $9eff means that the program can use up to
-	and including the address $9eff and that $9f00 is the first address out of bounds.
+	exceeds the given memtop address. This value is exclusive, so $a000 means that $a000 is the first address
+	that program can no longer use. Everything up to and including $9fff is still usable.
 
 
 .. data:: %option <option> [, <option> ...]
diff --git a/docs/source/todo.rst b/docs/source/todo.rst
index 2d3a6b05c..c3225e497 100644
--- a/docs/source/todo.rst
+++ b/docs/source/todo.rst
@@ -1,6 +1,21 @@
 TODO
 ====
 
+make repeat support 65536 iterations
+
+make memtop adjust automatically when you use %address larger than the default . Then simply set it at $ffff because apparently the programmer knows better?
+
+scripts/cx16_images : add an option to keep the first palette entry black (there's already the option to retain the first 16 entries)
+
+support this usage of defer:
+
+        if diskio.f_open(filename) {
+            defer diskio.f_close()
+            ...
+        }
+
+need help with: PET disk routines (OPEN, SETLFS etc are not exposed as kernal calls)
+
 ...
 
 
diff --git a/examples/cx16/zsmkit/demo2.p8 b/examples/cx16/zsmkit/demo2.p8
index 7c47d5e21..c17ff3d3b 100644
--- a/examples/cx16/zsmkit/demo2.p8
+++ b/examples/cx16/zsmkit/demo2.p8
@@ -1,7 +1,7 @@
 %import diskio
 %import textio
 %import zsmkit_high
-%memtop $8bff           ; zsmkit is loaded from 8c00 onwards
+%memtop $8c00           ; zsmkit is loaded from 8c00 onwards
 
 ;; Proof Of Concept ZSM player using a binary blob version of zsmkit by MooingLemur
 ;; This version is a bit simpler as "demo1".