Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!willett!ForthNet
From: ForthNet@willett.UUCP (ForthNet articles from GEnie)
Newsgroups: comp.lang.forth
Subject: Advanced Beginners
Message-ID: <537.UUL1.3#5129@willett.UUCP>
Date: 23 Feb 90 23:19:19 GMT
Organization: Latest link in the ForthNet chain.  (Pgh, PA)
Lines: 49


 Date: 02-22-90 (10:15)              Number: 2948 (Echo)
   To: IAN GREEN                     Refer#: 2605
 From: MICHAEL HOBSON                  Read: 02-22-90 (20:20)
 Subj: FORTH                         Status: PUBLIC MESSAGE

 >   Thanks, for the clarification. I assume that the address can be a 
 >symbol like 'HERE' or 'THERE' or 'CONTAINER' etc. As an extremely crude
 >example, lets try the following.
 >
 >CONSTANT UARTBASE 3F8 ;
 >
 >: CLR8250 6 FOR UARTBASE + 0 ! NEXT;
 >
 >Is this correct, the logic I am attempting to do is to write 0's to eac

 This example should be more like the following:

 HEX    ( Set Base to Hexadecimal )
 3F8 CONSTANT UARTBASE   ( CONSTANT expects a value on the stack. No
                           semicolon is needed here, because the text
                           scan for the constant's name terminates with
                           at the first whitespace character )

 : CLR8250  6 ( # of registers to clear )
            FOR

                0    ( value to store must be pushed first )

                UARTBASE I +    ( add loop index to base address )

                !               ( write zero to port address )

            NEXT   ;     ( semi-colon is a WORD and MUST be separated by
                           whitespace, the open-paren for defining these
                           comments is also a WORD and MUST be separated 
                           by whitespace. )

 Of course, the 8250 base address will be whatever you decide to decode 
 from the RTX 2001A address lines, so substitute as appropriate.
 I hope this helps somewhat.
 "The Elf" [^]-[^]
            \---/
 Elf - A wise and helpful variety of magical being.

 NET/Mail : British Columbia Forth Board - Burnaby BC - (604)434-5886   
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