Cell signedness examples

eg/README.markdown

@@ -61,11 +61,11 @@ information.
 | [pascserp.bf](pascserp.bf) | CC0     | Chris Pressey       | 7/12/97  | Generates a gasket (Serpinsky triangle) using Pascal's Triangle.
 | [pi.bf](pi.bf)             |         | Ben Olmstead        | 6/25/97  | Produces the first hundred digits of pi in under one hundred characters of Befunge, but cheats in that it simply decompresses the digits encoded in the source code.
 | [pi2.bf](pi2.bf)           |         | Kevin Vigor         | 7/2/97   | Generates the first hundred digits of Pi. It does this not by cheating, but actually calculating Pi; unfortunately it far exceeds 100 characters of Befunge code.
-| [prime.bf](prime.bf)       |         | Kalyna Zazelenchuk  | 9/5/93   | Lists the counting numbers incrementally from one and checks if each is prime.
+| [prime.bf](prime.bf)       |         | Kalyna Zazelenchuk  | 9/5/93   | Lists the integers between 2 and 127 (inclusive), and reports whether each one is prime. Also reports that -128 is not prime.
 | [rand.bf](rand.bf)         |         | Chris Pressey       | 9/5/93   | Generates random numbers between 1 and 9 as statistically evenly distributed as the computer's random number generator.
 | [rand10.bf](rand10.bf)     |         | Ken Bateman         | 4/12/97  | A 3x10 random number generator.
 | [rand11.bf](rand11.bf)     |         | Ken Bateman         | 4/12/97  | A 5x7 flexible random number generator. The number of bits is set with the 88+ at the top left. As shown this program will generate a random number from 0 to 32767.
-| [rand12.bf](rand12.bf)     |         | Ben Olmstead        | 4/24/97  | A 2x13, 0..255 random number generator.
+| [rand12.bf](rand12.bf)     |         | Ben Olmstead        | 4/24/97  | A 2x13 random number generator that generates numbers from -128 to 127. (On an interpreter with unsigned char cells, such as the one on which this example was originally developed, it will produce values from 0..255.)
 | [rand13.bf](rand13.bf)     |         | Ben Olmstead        | 4/24/97  | A 2x12, infinitely looping 0..31 random number generator.
 | [rand14.bf](rand14.bf)     |         | Greg Wright         | 5/18/97  | 4x7 random number generator.
 | [rand15.bf](rand15.bf)     |         | Artyom Baranov      | 4/5/96   | THE smallest Befunge RNG-16. (16x1)
@@ -94,5 +94,6 @@ information.
 | [switchbx.bf](switchbx.bf) |         | Zach Baker          | 7/10/97  | A real purty 'switch' statement.
 | [testbrdg.bf](testbrdg.bf) | CC0     | Chris Pressey       | 10/27/111| Tests whether the \# instruction interacts properly with wrapping.
 | [testmodu.bf](testmodu.bf) | CC0     | Chris Pressey       | 8/23/111 | Tests how your implementation of Befunge-93 calculates modulus (there is no right way.)
+| [testpfcl.bf](testpfcl.bf) | CC0     | Chris Pressey       | 10/5/118 | Prints out the largest and smallest values that can be stored in a playfield cell in your implementation of Befunge-93. A very large number of C compilers interpret `char` to mean a signed 8-bit value, so a very common result of running this is "127 -128".
 | [toupper.bf](toupper.bf)   | CC0     | Chris Pressey       | 9/5/93   | Converts letters to upper-case. An example of the \` (greater) statement.
 | [wumpus.bf](wumpus.bf)     | CC0     | Wim Rijnders        | 8/15/97  | The classic game of Hunt the Wumpus!

eg/prime.bf

@@ -1,4 +1,4 @@
-222p35*89+*11p>133p                   >33g1+33p   22g33g- v>22g33g%#v_v
+222p882**1+11p>133p                   >33g1+33p   22g33g- v>22g33g%#v_v
  o                                                        >|
   2                             v,,,,, ,,,,,.g22"is prime."<
    1                            >    v^                             <

eg/testpfcl.bf

@@ -0,0 +1,2 @@
+000p>00g1+01p01g00g`#v_00g.000p>00g1-01p00g01g`#v_00g.@
+    ^p00+1g00        <         ^p00-1g00        <