Help understanding letter sets

I am trying to understand the working of an old computer speech synthesizer (SAM for the commodore64) which uses a series of rules to break English text into a string of phonemes. The rules make some frequent tests for membership of the following letter sets:

``````//  0x04        [ D J L N ]
//  0x08        [ B D G J L M N R V W Z ]
//  0x10        [ C G J S X Z R S T Z ]
``````

Is anyone able to spot what traits the following sets may have and why they are significant?

Would I be correct in thinking the 0x10 set are fricatives?

Thanks in advance for any insight you can provide.

• What are these? Letters typed in English? Codes for individual phonemes? How does the synthesizer work? What's the input like? Feb 7, 2017 at 16:42
• Since it was said that the code is there breaks English text into phonemes and to sort letters into groups, I suppose these are actual letters rather than symbols encoding phonemes. Feb 7, 2017 at 17:25
• For all letters, there are associated 'flags' which denote that the letter belongs to a specific set (the meaning of each set is what I aim to deduce.) One letter can belong to multiple sets. So above, the letters D,J,L and N all belong to one set, which the computer marks with the number 0x04. As an example, here is a rule defined by the system: ``` '.(S) =Z' ``` Feb 7, 2017 at 18:01
• If the rule on the left hand side of the = is matched then the Phoneme encoded in text on the right hand will be output. As best I can see, the '.' here will match any of the characters in set 0x08. The ' ' character on the right hand side of the parenthesis will match against any letter at all. The rule as a whole will match any letters in set 0x08 if they are followed by a 'S' character and any other alpha character. I'm not sure if that will clear anything up, but hopefully is shows a little more of the context for this question. Feb 7, 2017 at 18:06
• This resembles regexp methods of decomposing segments into features, without particular concern for phonetics. There must be more that just 3 such sets: the "meaning" of the sets would emerge from looking at what all of the sets are, e.g. what other sets is "D" a member of? "R" is in x'08, x'10, "L" is in x'04, x'08, so inferring the "meaning" would require having the total list. Feb 7, 2017 at 18:41

• `D` [d], `L` [l], `N` [n] are all voiced alveolar consonants; `J` (usually pronounced [dʒ]) is postalveolar
• `[ B D G J L M N R V W Z ]` are all voiced; `[ J L M N R V W Z ]` are also sonorants, but `[ B D G ]` are not
• `C`(when pronounced [s]), `G` (when pronounced [dʒ]), `J` ([dʒ]) `S` ([s] or [ʃ] in "sh"), `X` ([ks]) `Z` ([z]) are sibilants; however `G` when pronounced [g], `C` when pronounced [k] and `R` ([ɹ], or [ɻ],), `T` ([t]) don't quite fit in there and I don't know why `S` and `Z` occur twice in the row.