Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.forth > #58545

Re: microFORTH

Show all headers | View raw

hughaguilar96@gmail.com wrote:
> On Monday, May 1, 2017 at 8:02:00 PM UTC-7, HAA wrote:
> > Elizabeth D. Rather wrote:
> > > On 5/1/17 2:36 PM, HAA wrote:
> > > > David Schultz wrote:
> > > >> On 04/25/2017 03:15 AM, JUERGEN wrote:
> > > >>> microFORTH documentation is available on the FORTH, INC. website. Not
> > > >>> a new product - but many here will probably remember it. And might
> > > >>> have a look after many years ...
> > > >>>
> > > >>
> > > >> I don't know how useful it is, unless you want examples of bugs.
> > > >>
> > > >> It starts off with the definition of LOAD:
> > > >>
> > > >> : LOAD BLK C@ <R IN @ <R 0 IN ! 8* OFFSET @ + F9F DROP
> > > >>     BLK ! INTERPRET R> IN ! R> BLK C! ;
> > > >>
> > > >> The value in BLK is saved and restored using C@ and C! yet it has to
> > > >> have a larger range than that and the new value is set using !.
> > >
> > > Actually, this is for the 1802, which had a development system using
> > > 250K floppies! This is 1978, folks. And BLK is a user variable, so it
> > > had to be 16 bits. That ! is pretty tacky, but it wouldn't cause a
> > > failure. Obviously the "endianness" worked ok.
> >
> > 'blocks' were 128 bytes.  While any screen on the disk could be LOADed
> > thanks to ! , the C@ C! would limit use of the word "LOAD" to screens 1-31
> > by my calculation.  Not a big deal for floppy size storage.
>
> C@ doesn't sign extend --- not nowadays anyway --- so the range would have been [0,255].
>
> If the floppies were 250KB, and the processor was little-endien, the code would have
> worked despite the bug.

There's no bug.  When referencing a disk block, BLK is 16 bits.
However as BLK and IN represent 3 contiguous bytes, a mix of
C@ C! ! @ were needed to save/restore/zero both BLK and IN.

Back to comp.lang.forth | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

microFORTH JUERGEN <epldfpga@aol.com> - 2017-04-25 01:15 -0700
  Re: microFORTH "HAA" <someone@microsoft.com> - 2017-04-26 09:35 +1000
    Re: microFORTH "Elizabeth D. Rather" <erather@forth.com> - 2017-04-25 14:15 -1000
      Re: microFORTH lehs <skydda.barnen@gmail.com> - 2017-04-25 23:09 -0700
      Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-01 11:15 +1000
  Re: microFORTH David Schultz <abuse@127.0.0.1> - 2017-04-30 15:02 -0500
    Re: microFORTH rickman <gnuarm@gmail.com> - 2017-04-30 21:13 -0400
      Re: microFORTH David Schultz <abuse@127.0.0.1> - 2017-04-30 20:24 -0500
        Re: microFORTH rickman <gnuarm@gmail.com> - 2017-05-01 21:02 -0400
          Re: microFORTH Rod Pemberton <NeedNotReplyHere@xrsevnneqk.cem> - 2017-05-02 05:58 -0400
          Re: microFORTH Coos Haak <htrofhc@gmail.com> - 2017-05-02 15:13 +0200
            Re: microFORTH rickman <gnuarm@gmail.com> - 2017-05-02 11:44 -0400
              Re: microFORTH David Schultz <abuse@127.0.0.1> - 2017-05-04 16:54 -0500
    Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-02 10:36 +1000
      Re: microFORTH "Elizabeth D. Rather" <erather@forth.com> - 2017-05-01 15:20 -1000
        Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-02 13:01 +1000
          Re: microFORTH hughaguilar96@gmail.com - 2017-05-01 20:42 -0700
            Re: microFORTH hughaguilar96@gmail.com - 2017-05-01 21:27 -0700
              Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-02 17:05 +1000
                Re: microFORTH "Elizabeth D. Rather" <erather@forth.com> - 2017-05-01 21:18 -1000
          Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-02 16:45 +1000
          Re: microFORTH JUERGEN <epldfpga@aol.com> - 2017-05-02 00:08 -0700
          Re: microFORTH hughaguilar96@gmail.com - 2017-05-02 11:36 -0700
            Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-03 10:43 +1000
              Re: microFORTH hughaguilar96@gmail.com - 2017-05-02 19:45 -0700
              Re: microFORTH Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-05-03 04:41 -0500
              Re: microFORTH David Schultz <abuse@127.0.0.1> - 2017-05-04 17:03 -0500
                Re: microFORTH "Elizabeth D. Rather" <erather@forth.com> - 2017-05-04 12:58 -1000
                Re: microFORTH "HAA" <someone@microsoft.com> - 2017-05-05 12:57 +1000
        Re: microFORTH David Schultz <abuse@127.0.0.1> - 2017-05-04 16:57 -0500
    Re: microFORTH Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-05-02 04:11 -0500
      Re: microFORTH Andrew Haley <andrew29@littlepinkcloud.invalid> - 2017-05-02 04:16 -0500
      Re: microFORTH Howerd <howerdo@yahoo.co.uk> - 2017-05-02 05:25 -0700
        Re: microFORTH "Elizabeth D. Rather" <erather@forth.com> - 2017-05-02 10:07 -1000
      Re: microFORTH David Schultz <abuse@127.0.0.1> - 2017-05-04 17:15 -0500

csiph-web