Hewlett Packard HP-48 BrainF*** Interpreter (UserRPL) by Jeffry Johnston
Released April 29, 2001

Key to Symbols (for the plaintext version of this document)
--------------
<<      Opening guillemet (purple above the "-" key)
>>      Closing guillemet
<=      Less than or equal to
a{      Alpha key
<-      Left shift arrow (purple)
->      Right shift arrow (cyan)
y:      Lowercase y, umlaut accent (character 255)

Custom Keyboard Program (push CST and NXT to access more chars)
-----------------------
® { "<" ">" "+" "-" ", "@" "[" "]" "." "." "˜" } MENU ¯
'KEYS' STO

Manual entry of special characters (also PRG for table)
----------------------------------
>       à2
<       à2
+       à+
-       à-
.       .
,       .
[]      x (multiplication key)
@       àENTER
LF      . (must push ENTER after using LF)
˜ (255) àYà9

Sample BF program
-----------------
",+[-.,+]@"
'SOURCE' STO

BF Interpreter Program
----------------------
®
"                     " 'SCRN' STO
CLLCD SCRN 0 DISP
{ 1 5000 } 0 CON 'DATA' STO
0 'QUIT' 0 'IPP' 1 'MP' STO STO STO
DO
  'IPP' INCR DROP
  SOURCE IPP IPP SUB NUM 'IPV' STO
  DATA MP GET 'MPV' STO
  IF 'IPV==43' THEN DATA MP MPV 1 + 256 MOD PUT 'DATA' STO END
  IF 'IPV==45' THEN DATA MP MPV 1 - 256 MOD PUT 'DATA' STO END            
  IF 'IPV==60' THEN 'MP' DECR DROP END 
  IF 'IPV==62' THEN 'MP' INCR DROP END 
  IF 'IPV==64' THEN 1 'QUIT' STO END         
  IF 'IPV==46' THEN SCRN 2 22 SUB MPV CHR + 'SCRN' STO SCRN 0 DISP END    
  IF 'IPV==44' THEN DATA MP SCRN "" INPUT NUM PUT 'DATA' STO END     
  IF 'IPV==93' THEN 'IPP' STO END      
  IF 'IPV==91' THEN  
    IF 'MPV==0' THEN
      1 'LVL' STO
      DO
        'IPP' INCR DROP
        SOURCE IPP IPP SUB NUM 'IPV' STO
        IF 'IPV==91' THEN 'LVL' INCR DROP END
        IF 'IPV==93' THEN 'LVL' DECR DROP END
      UNTIL 'LVLó0' END  
    ELSE
      IPP 1 -
    END
  END
UNTIL 'QUIT' END
SCRN 5 22 SUB
'DATA' 'MP' 'MPV' 'IPP' 'IPV' 'LVL' 'QUIT' 'SCRN'
PURGE PURGE PURGE PURGE PURGE PURGE PURGE PURGE
¯
'BF' STO

Variables Used (* Purged automatically on BF exit)
--------------
BF      BF Interpreter
SOURCE  BF Program Source
KEYS    Custom Keyboard Program
*DATA    Memory (5000 bytes)
*MP      MP - Memory Pointer
*MPV     [MP]
*IP      IP - Instruction Pointer
*IPV     [IP]
*LVL     Bracket depth
*QUIT    End Program?
*SCRN    Text Output Screen