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Re: Abersoft Forth disassembled

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En/Je/On 2015-09-07, Hans Bezemer <the.beez.speaks@gmail.com>
escribió/skribis/wrote:

> Marcos Cruz wrote:
>
>> Some months ago I disassembled Abersoft Forth, a fig-Forth 1.1
>> implementation customized for ZX Spectrum, written by John
>> Jones-Steele and published by Melbourne House in 1983.

> Ever heard of "Advanced Spectrum Forth" by Don Thomasson? 

Of course. It's an excellent book on Abersoft Forth.  It was very
helpful during the long process writting the programs to extract the
data needed to recreate the original Z80 source.  The book includes a
disassembly, but it uses a kind of abbreviated pseudo-code for the
low-level code, and no actual memory addresses at all except for the
fig-Forth parameter area and user variables.

The book has few errors, but one of them is especially funny: The author
shows the definition of `EXIT` with a warning, but without realizing the
word is buggy. I fixed this bug as part of a library I wrote for
Abersoft Forth:

  \ ............................................
  \ Fix the `EXIT` bug

  \ `EXIT` must do `R> DROP`, not `>R DROP`
  \
  \ Even Don Thomasson's _Advanced Spectrum Forth_ (1984) shows
  \ the wrong definition of `EXIT` (page 131)... and with the
  \ following notice: "This word needs to be used with extreme
  \ care." Indeed, because it crashes the system. The fix is
  \ easy:

' R> CFA ' EXIT !

-- 
Marcos Cruz
http://programandala.net

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Abersoft Forth disassembled Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-06 17:30 +0000
  Re: Abersoft Forth disassembled Coos Haak <chforth@hccnet.nl> - 2015-09-07 00:21 +0200
    Re: Abersoft Forth disassembled Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-07 00:20 +0000
  Re: Abersoft Forth disassembled Hans Bezemer <the.beez.speaks@gmail.com> - 2015-09-07 17:54 +0200
    Re: Abersoft Forth disassembled Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-07 20:58 +0000
  Re: Abersoft Forth disassembled Alexander Skobelev <al.skobelev@gmail.com> - 2015-09-09 15:11 +0300
    Re: Abersoft Forth disassembled Mark Wills <markwills1970@gmail.com> - 2015-09-09 08:47 -0700
      Re: Abersoft Forth disassembled hughaguilar96@gmail.com - 2015-09-10 21:32 -0700
        Re: Abersoft Forth disassembled "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-09-11 01:30 -0400
    Re: Abersoft Forth disassembled Marcos Cruz <null_email_so_use_my_contact_page@programandala.net> - 2015-09-19 19:09 +0000

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