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       º  Lesson 7 Part 130 F-PC 3.5 Tutorial by Jack Brown  º
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         ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
         ³  Control Your Printer with CREATE ... DOES>   ³
         ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ

Here is another application of CREATE ... DOES> .  Remember that this
idea of extending the compiler is new and unheard of in other languages.
You will have to become familiar with all of the examples I have
presented and then try to think of variations or application of the
ideas to new areas.

You just bought a fancy EPSON FX85+ printer (or one of the many clones).
It comes with a manual 1.5 inches thick documenting all the features and
the escape sequences necessary to activate them.  Some of features
require only one control code, some require 2 codes to be sent and yet
others require more than 2 codes.

Here is the defining word that will create printer extensions. We are
using EPSON FX85 printer control sequences for the examples.
Usage would be as follows:

1) Only one code to be sent.
   15 1 FEATURE COMPRESSED   \ 15 or ^O is the EPSON code for this mode.

2) Two codes must be sent. Note that the order of the codes is the
   reverse of the order they will be sent.
   64 27 2 FEATURE EPSON-RESET \ 27 64 , or ESC @ will resets printer.

3) Three codes required.
   49 78 27 3 FEATURE NEAR-LETTER-QUALITY
   \ 27 78 49 or ESC "x1" will put FX85+ into NLQ mode.

k) If k codes were required you would follow the pattern below always
   with the codes in the reverse order from the manual.  ie reverse
   polish notation!  If you look at the definition you will see that
   since the top stack number is compiled first they will actually
   be compiled in the correct order in memory.
   n1 n2 ... nk  k FEATURE  <name>

\ Print feature defining word.
: FEATURE  ( n1 n2...nk k    -- )
                    \ Below is the compile time routine.
   CREATE DUP C,    \ Duplicate and compile the number of codes.
    0 ?DO C, LOOP   \ Compile k codes to be sent to the printer
                    \ This is the run time routine.
    DOES>   COUNT   \ Fetch number of codes and increment address.
    0 ?DO   COUNT   \ Fetch a code.
           (PRINT)  \ Send code to printer only.
       LOOP ;       \ Loop till all codes sent.

Notes:

1) The word COUNT ( addr   addr+1 char ) actually fetches the byte
   stored at  addr  and then increments addr by 1.  Its definition
   would be  : COUNT  DUP 1+ SWAP C@ ;

2) (PRINT) is an F-PC word that emits or sends the character
   corresponding to the top stack number to the printer only.

Now all you have to do is go through the control code reference card
at the end of the manual and make words for each series of codes.  You
can even combine features.

ASCII M 27 ASCII E 27 ASCII @ 27 6 FEATURE EMPHASIZED-ELITE

This will reset the printer, put it in emphasized mode, and
select elite pitch.

ÖÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ·
º  Problem 7.10 º
ÓÄÄÄÄÄÄÄÄÄÄÄÄÄÄĽ
a) Test FEATURE and provide examples of several other commands.
b) Make a version of FEATURE that can send ANSI codes to the console.
   To test your word you will have to turn off F-PC direct screen writes
   by using the command  SLOW.

ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³  Please Move to Lesson 7 Part 140  ³
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