diff --git a/Makefile b/Makefile
index 4495652a..8445120a 100644
--- a/Makefile
+++ b/Makefile
@@ -192,7 +192,7 @@ build/newc65.rom: build/kernal_mega65.rom build/basic_mega65.rom build/chargen.r
 
 # Rules - tests
 
-.PHONY: test test_generic test_mega65 test_ultimate64 test_m65 testremote testsimilarity
+.PHONY: test test_generic test_mega65 test_ultimate64 test_hybrid test_m65 testremote testsimilarity
 
 test: test_generic
 
diff --git a/STATUS.md b/STATUS.md
index 92e8e0cd..dd27dfb2 100644
--- a/STATUS.md
+++ b/STATUS.md
@@ -76,6 +76,8 @@ Not all of them - only these we want to have implemented.
 | Address   | Name         | Status   |  Remarks                                           |
 | :-------: | :----------- | :------: | :------------------------------------------------: |
 | `$A004`   | revision str | DONE     |                                                    |
+| `$A533`   | LINKPRG      | NOT DONE |                                                    |
+| `$A659`   | set txt ptr  | NOT DONE |                                                    |
 | `$A68E`   | RUNC         | NOT DONE |                                                    |
 | `$A7AE`   | NEWSTT       | NOT DONE |                                                    |
 | `$AB1E`   | STROUT       | DONE     |                                                    |
diff --git a/c64/basic/a533.interop b/c64/basic/a533.interop
new file mode 100644
index 00000000..46ed7adf
--- /dev/null
+++ b/c64/basic/a533.interop
@@ -0,0 +1,7 @@
+This routine is used to launch other software. It is used by:
+
+- Uncrunch (see https://github.com/mist64/pucrunch/blob/master/uncrunch.asm)
+- FileBrowser64 (FB64) - found by debugging
+
+and probably others.
+
diff --git a/c64/basic/a533.linkprg.s b/c64/basic/a533.linkprg.s
new file mode 100644
index 00000000..b7b11e80
--- /dev/null
+++ b/c64/basic/a533.linkprg.s
@@ -0,0 +1,6 @@
+
+// XXX provide documentation and implementation
+// see: https://www.lemon64.com/forum/viewtopic.php?t=64721&sid=bc400a5a6d404f8f092e4d32a92f5de7
+
+LINKPRG:
+    STUB_IMPLEMENTATION()
diff --git a/c64/basic/a659.interop b/c64/basic/a659.interop
new file mode 100644
index 00000000..925b8462
--- /dev/null
+++ b/c64/basic/a659.interop
@@ -0,0 +1,6 @@
+This routine is used to launch other software. It is used by:
+
+- Exomizer (see https://github.com/bitshifters/exomizer/blob/master/exomizer/exomizer115.txt)
+- FileBrowser64 (FB64) - found by debugging
+
+and probably others.
diff --git a/c64/basic/a659.setcharptr.s b/c64/basic/a659.setcharptr.s
new file mode 100644
index 00000000..b7383332
--- /dev/null
+++ b/c64/basic/a659.setcharptr.s
@@ -0,0 +1,7 @@
+
+// XXX provide documentation and implementation
+// see: https://www.lemon64.com/forum/viewtopic.php?t=64721&sid=bc400a5a6d404f8f092e4d32a92f5de7
+//      https://www.lemon64.com/forum/viewtopic.php?t=70680&sid=3ff66caf7f5fdf2a3c2ff2ee31fc3fd8
+
+setcharptr:
+    STUB_IMPLEMENTATION()
diff --git a/c64/basic/a7ae.interop b/c64/basic/a7ae.interop
index f5ae9e65..25da9736 100644
--- a/c64/basic/a7ae.interop
+++ b/c64/basic/a7ae.interop
@@ -1,3 +1,9 @@
-This routine is mentionned in the cartridge writing tutorial here: https://codebase64.org/doku.php?id=base:assembling_your_own_cart_rom_image
+This routine is used to launch other software. It is used by:
+
+- Exomizer (see https://github.com/bitshifters/exomizer/blob/master/exomizer/exomizer115.txt)
+- FileBrowser64 (FB64) - found by debugging
+
+and probably others. It is also mentionned in the cartridge writing tutorial here:
+
+- https://codebase64.org/doku.php?id=base:assembling_your_own_cart_rom_image
 
-We have to implement (or at least provide stub), otherwise cartridges will crash.
diff --git a/c64/basic/a7ae.newstt.s b/c64/basic/a7ae.newstt.s
index 55b97764..542e7bc6 100644
--- a/c64/basic/a7ae.newstt.s
+++ b/c64/basic/a7ae.newstt.s
@@ -1,5 +1,8 @@
 
 // XXX provide documentation and implementation
+// see: https://www.lemon64.com/forum/viewtopic.php?t=64721&sid=bc400a5a6d404f8f092e4d32a92f5de7
+//      https://www.lemon64.com/forum/viewtopic.php?t=70680&sid=3ff66caf7f5fdf2a3c2ff2ee31fc3fd8
+//      https://codebase64.org/doku.php?id=base:assembling_your_own_cart_rom_image
 
 NEWSTT:
-	STUB_IMPLEMENTATION()
+    STUB_IMPLEMENTATION()
diff --git a/c64/kernal/f4a5.load.s b/c64/kernal/f4a5.load.s
index e1cccc1d..0a838d91 100644
--- a/c64/kernal/f4a5.load.s
+++ b/c64/kernal/f4a5.load.s
@@ -142,6 +142,6 @@ load_loop:
 
 	lda FA
 	jsr close_load
-
+.break
 	// Return last address
 	jmp lvs_return_last_address