error handling?

1 files changed, 11 insertions, 2 deletions

diff --git a/readme.md b/readme.md
index 7f34a62..e7c84be 100644
--- a/readme.md
+++ b/readme.md
@@ -69,8 +69,17 @@ maybe this sucks shit but my idea is that i compile in a relative jmp with
 
 ### PNO
 'pictured numeric output'. its forth's numeric output functionality.
-this is me trying to describe it so i can figure it out and implement it.
 note that this forth doesn't have double numbers
 (i don't think it's necessary, since cells are 64 bit)
 so PNO works on single cell values.
-PNO is started by `<#` and ended by `#>`.
+
+### error codes
+in order to have Good Error Handling anywhere, the error handler's xt
+is stored in the `handler` variable and is then called by loading its value
+and `execute`ing it. the actual description of the error comes from the
+`error` variable (in case the stack is fucked)
+
+the error codes are:
+
+- 0: nothing.
+- 1: stack underflow