AGI Specifications: 2.8 Interpreter Version Differences

2.8 Interpreter Version Differences

by Lance Ewing
Last updated: 27 January 1998
Retrived from the Internet Archive

There are a number of different versions of the AGI interpeter but generally the data formats are the same or can easy be converted between each other. The following table is a list of AGI interpreter versions that I know of:

AGI Version	Interpreter File Size	AGIDATA.OVL Size	Number of Commands	OBJECT File Encrypted	LZW Used In VOL Files
2.089	34305	6656	155	No	No
2.272	34816	6656	161	No	No
2.411	38400	7680	169	Yes	No
2.435	38400	7680	169	Yes	No
2.439	38400	7680	169	Yes	No
2.440	38400	7680	169	Yes	No
2.915	39424	8192	173	Yes	No
2.917	39424	8192	173	Yes	No
2.936	39424	8192	175	Yes	No
3.002.086	40866	8064	177	Yes	Yes
3.002.098	40898	8080	181	Yes	Yes
3.002.102	40898	8080	181	Yes	Yes
3.002.107	40962	8080	181	Yes	Yes
3.002.149	40520	7488	181	Yes	Yes

AGI
Version

Interpreter
File Size

AGIDATA.OVL
Size

Number of
Commands

OBJECT File
Encrypted

LZW Used In
VOL Files

2.089

34305

6656

155

2.272

34816

6656

161

2.411

38400

7680

169

Yes

2.435

38400

7680

169

Yes

2.439

38400

7680

169

Yes

2.440

38400

7680

169

Yes

2.915

39424

8192

173

Yes

2.917

39424

8192

173

Yes

2.936

39424

8192

175

Yes

3.002.086

40866

8064

177

Yes

3.002.098

40898

8080

181

Yes

3.002.102

40898

8080

181

Yes

3.002.107

40962

8080

181

Yes

3.002.149

40520

7488

181

Yes

This table illustrates a number of things.

Firstly, as the interpreter version increased, the number of AGI commands supported increased with it. The last eleven we do not know the names of.

There are two main AGI versions: AGI v2 and AGI v3.

The early AGI v2 games did not encrypt the OBJECT file with the "Avis Durgan" string.

AGI v3 games use adaptive LZW to compress their LOGIC, VIEW, and SOUND files.

COMMAND ARGUMENT NUMBER DESCREPENCIES

There are four commands that have changed the number of arguments that are passed to them. All this information is based on observations made of the above interpreter versions.

(i) The quit command had no arguments for version 2.089 whereas all the others above have one argument.

(ii) The print.at and print.at.v commands had only three arguments for versions 2.089 - 2.400 and four for the other versions.

(iii) Unknown command number 176 had one argument for version 3.002.086 but later versions had no arguments for this command.

AGI VERSION THREE

There are a number of other differences between AGI v3 and AGI v2.

The LOGIC files do not encrypt the text messages with "Avis Durgan" since there is no need to do this because it is compressed anyway.

The PICTURE file format is slightly different for picture codes 0xF0 and 0xF2, i.e. the codes that change the visual colour and priority colour. The difference is that only 4-bits are used to store the colour as opposed to 8-bits in AGI v2.

NUMBER OF STRINGS

There may be some differences in the number of strings supported by some interpreters as well. All interpreters have at least 12 strings. Most interpreters have space for 24 strings but I don't know if the extra space is used for strings or not.

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