COMMENT ⊗   VALID 00005 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	Possible games
C00003 00003	Games requiring a stored vocabulary
C00009 00004	Text storage with data compression
C00015 00005	Penny matching
C00017 ENDMK
C⊗;
Possible games

1)  Reversie (Othello)
2)  Kalah
3)  3-dimensional Tic Tac Toe
4)  Master-mind
5)  Nine men's Morris (Muhle, Marelle, The Mill or Merry Peg)
6)  Hex
7)  Battleship
8)  Matching pennies
9)  Scrabble
10) Sprouts
11) Backgammon
12) Chinese Checkers (so called)
13) Go Moku
14) Checker monitor
15) Bingo
16) Parcheesi
17) Chess
18) Chess monitor
19) Go
20) Nim
Games requiring a stored vocabulary

It would be nice to be able to have the computer act as a referee for word
games and also to allow a single player to play against the machine.  All
such games would require a stored vocabulary.

There are several techniques for minimizing the storagre space required
for a vocabulary.  One of these that seems to fit our needs is outlined
below.

The left 3 bits of each byte would contain a number specifying the
character position in a word of the character that is contained in the
last 5 bits of the byte.  In this way, only 1 byte is used to specify the
first character of all words that begin with any given character.
Similarly, if there are 2 or more words with the first 2 characters in
common, then only one more byte is used to specify the second letter of
these words.  The same economy in bytes continues for all character
positions in the words.

Unfortunately, one could not store the characters in the form needed to
display them, as this requires 6 bits, but a 26-byte table would take care
of the conversion if only letters were to be allowed.

In the example shown below, the average number of bytes per word is 2.1.
This number depends upon the character of the vocabulary, and it is less
if multiple endings are shown for all root words.  One could, never-the
less, store a vocabulary of close to 1000 words in 2 K and perhaps write a
simple word game in 4 K of ROM.  Of course, 1000 words is a pretty small
vocabulary and one would like to have a good many more words.

Perhaps a better compromise would be to plan on 8 K of ROM and then to use
6 K of this for a vocabulary of 3000 words, still leaving 2 K for the
program.  One would still have to limit the allowed length of the words
that could be used to 8 characters in order to be able to specify the
character position in 3 bits.

A sample 5-character-word vocabulary excerpt is shown below.  Note that
the numbering could start with 0, thus allowing 8 letter words.  Also some
economy in searching the vocabulary may be achieved by storing it in reverse
word order, and by using the last 3 bits of each byte for the number rather
than the first 3 as shown.

    Characters (shown staggered)	    Word #   Total bits

1A	2B	3A	4-			1	4	
			4C	5K		2	6	
			4F	5T		3	8	
			4C	5E		4	10	
			4S	5H		5	12	
			4T	5E		6	14	
		3B	4Y			7	16	
			4O	5T		8	18	
		3E	4D			9	20	
			4T 			10	21	
		3H	4O	5R		11	24
		3I	4D	5E		12	27	
		3L	4E			13	29	
			4Y			14	30
		3O	4D	5E		15	33	
			4R	5T		16	35	
			4U	5T		17	37
			4V	5E		18	39	
		3U	4S	5E		19	42	
			4T	5-		20	44	
				5S		21	45	
	2C	3E	4-			22	48	
			4S	5-		23	50
		3H	4E	5-		24	53	
				5S		25	54
		3I	4D	5-		26	57	
				5S		27	58	
		3N	4E	5-		28	61	
				5S		29	62
		3O	4C	5K		30	63	
			4R	5N		31	65	
		3R	4E	5-		32	68	
				5S		33	69
			4I	5D		34	71	
		3T	4-			35	73
			4O	5R		36	75	
			4S			37	76	
	2D	3A	4G	5E		38	80	
			4P	5T		39	82	
		3D	4-			40	84	
			4A	5X		41	86	
			4E	5R		42	88	
			4L	5E		43	90	
			4S			44	91	
		3E	4P	5T		45	94
		3I	4T	5-		46	97	
		3M	4I	5T		47	100	
		3O	4-			48	102	
			4B	5E		49	104	
			4P	5T		50	106	
			4R	5E		51	108	
				5N		52	109	
		3U	4L	5T		53	112	
			4S	5T		54	114

Average	number	of	bytes	per	word	2.1

Text storage with data compression

Text storage in the Video-Brain can present a problem.  The size of
the available memory will usually be too small to permit the storage of the
desired amount of text without some sort of compression while the amount
of text to be stored is still too small to justify a very complicated text
compression scheme which would require an elaborate decoding program.

Some saving in space with ordinary text can be achieved without resorting
to a very complicated code if one is willing to forgo the use of upper and
lower case and if one limits the number of characters that are to be
stored..  One such code as discribed below will result in the storing of
approximately 1.7 characters per byte as compared with 1,33 for a packed
6-bit code. One would have to make a detailed study of the relative size of
the program required to use this scheme as compared to the size of the program
to do simple packing before one could be sure that this saving would be worth
while.

We will assume that one wants to use 26 letters, the digits 0 through 9
and 3 punctuation marks,  , . and ? and that we want the code to consist
of 4-bit "nibbles" which can be packed two to a byte.  It is assumed that 
there would be no need for a carriage return signal and that this function
would be handled automatically by padding with spaces to the end of a fixed
length line.

There would be three modes, a normal-letter mode, a temporary
alternate-letter mode, and a digit mode, with certain nibbles while in the
normal-letter mode and in the digit mode reserved as mode changing
signals.  The scheme as outlined could be extended to provide for yet
another mode, probably a temporary mode to allow for the inclusion of 16
additional but seldom used characters, if this seemed desirable.

When in the normal-letter mode, nibble 0 would stand for a space, nibbles
1 thru 13 would stand for the 13 most commonly used letters, with nibbles
of 14 and 15 reserved for mode changing signals.  Nibble 14 would result in
a temporary one-character change to the alternate-letter mode, with the
mode then reverting to the normal-letter mode.  Nibble 15 would result in
a change to the digit mode for all following nibbles.

When in the alternate-letter mode the nibbles 0 thru 12 would represent
the remaining letters with 13 thru 15 standing for the 3 punctuation
marks.  This mode would persist for only one character and the mode would
then revert to one of the other modes as determined by the signal that
called this temporary mode.

When in the digit mode, the nibbles 0 thru 9 would represent the digits 0
thru 9 with nibble 10 standing for a period or decimal mark.  These
nibbles would not result in any change from the digit mode.  Nibble 11
would cause a temporary change to the normal-letter mode, nibble 12 would
indicate a switch to the normal-letter mode, nibble 13 would indicate a
temporary shift to the alternate-letter mode with a return to the digit
mode, while nibble 14 would indicate a temporary shift to the
alternate-letter mode for one character and a mode change thereafter to
the normal-letter mode.  Nibble 15 is unassigned but it could be used to
invoke yet another temporary mode that could contain 16 desired but seldom
used characters.
Penny matching

It is possible to write a simple program which will usually out-play a
person who choses heads or tails and then lets the program "guess" what
his choice had been.  For the scheme to work the result of each trial must
be reported to the program correctly and it then depends upon the fact
that a person simply cannot behave in a truly random fashion.

The only way that a person can hope to outguess the program is for him to
actually flip a coin or use some other random device to make his choice
for him and then, of course, he will fool the program only half the time.
Most people refuse to believe that a computer program can be this smart
and they feel intuitively that their chances are better if they make the
decisions.