diff --git a/README.md b/README.md
index bb05770..e542c2e 100644
--- a/README.md
+++ b/README.md
@@ -9,12 +9,13 @@ Memory access in this mod occurs over digilines, with the channel as the prefix
 |Default| 15		| get	| DefaultF	| get		|
 
 ## T400
+The T400 is a 12-bit stack machine operating at 1Hz (due to ABMs only running once per second). It has a 16-word stack, 0 registers and a very simple instruction set.
 ### Instructions
-TOS = top of stack
+There are 8 instructions for the T400. Any values encountered by the processor that are not instructions are treated as data and pushed to the stack. While this does make both the code for the emulator and the code for the emulated computer simple, it has the downside that if you really do want the value 4095 you have to add two things together.
 
 | ins	 | function			|    mnemonic	|
 |--------|------------------------------|---------------|
-|4095	 | duplicate TOS		| dup		|
+|4095	 | push program counter		| ppc		|
 |4094	 | swap TOS			| swp		|
 |4093	 | read memory from TOS		| read		|
 |4092	 | write to memory from TOS	| write		|
@@ -23,5 +24,8 @@ TOS = top of stack
 |4089	 | jump to TOS			| jmp		|
 |4088	 | skip if TOS = zero		| sez		|
 
+## T410
+The T410, is, in essence, the write instruction in a block. You put in an address and a value and it tries to write the value to that address.
+
 ## T416
 The T416 is a 16-word memory. It stores 16 ints and is accessed as described in the Memory access section.