recipes/rc2014/selfhost: add verification instructions

recipes/rc2014/selfhost/README.md

@@ -77,3 +77,14 @@ You're looking at the offset of the last wordref of the *previous* LOAD
 operation. That offset is going in `XCURRENT`. Then, you're looking at the end
 of that word. That offset goes in `HERE`. Once you've done that, relaunch your
 LOAD.
+
+### Verifying
+
+You can use `/tools/memdump` to dump the memory between your start/stop offsets
+so that you can compare against your reference stage 1. Before you do, you have
+to take yourself out of xcomp mode. First, run `XCOFF` to go back to your
+regular dict. Then, run `FORGET CODE` to undo the xcomp overrides you've added
+before. That will rewind `HERE`. You don't want that. Put `HERE` back to after
+your ending offset so that you don't overwrite your binary.
+
+Then, you can run `/tools/memdump`.

tools/memdump.c

@@ -5,7 +5,7 @@
 
 #include "common.h"
 
-/* Read specified number of bytes at specified memory address through a BASIC
+/* Read specified number of bytes at specified memory address through a Forth
  * remote shell and dump it to stdout.
  */
 
@@ -29,9 +29,7 @@ int main(int argc, char **argv)
 
     int fd = open(argv[1], O_RDWR|O_NOCTTY);
     char s[0x30];
-    sprintf(s, "m=0x%04x", memptr);
-    sendcmdp(fd, s);
-    sprintf(s, "while m<0x%04x peek m:puth a:m=m+1", memptr+bytecount);
+    sprintf(s, ": _ 0x%04x 0x%04x DO I @ .x LOOP ; _", memptr+bytecount, memptr);
     sendcmd(fd, s);
 
     for (int i=0; i<bytecount; i++) {
@@ -41,5 +39,6 @@ int main(int argc, char **argv)
         putchar(c);
     }
     read(fd, s, 2); // read prompt
+    sendcmdp(fd, "FORGET _");
     return 0;
 }