APF Imagination Machine BASIC tokenized file - Revision history

Dan Tobias at 21:51, 13 July 2019

2019-07-13T21:51:49Z

Dan Tobias: /* Other links and references */

2014-08-23T13:14:53Z

‎Other links and references

Dan Tobias: /* Software */

2014-08-23T13:14:21Z

‎Software

Dan Tobias: /* Software */

2014-05-06T03:46:40Z

‎Software

Dan Tobias: /* Other links and references */

2014-02-15T17:30:19Z

‎Other links and references

Jsummers at 16:57, 15 February 2014

2014-02-15T16:57:32Z

Dan Tobias at 13:49, 13 June 2013

2013-06-13T13:49:33Z

Dan Tobias at 04:32, 20 January 2013

2013-01-20T04:32:49Z

Dan Tobias at 20:32, 19 January 2013

2013-01-19T20:32:37Z

Dan Tobias at 16:12, 19 January 2013

2013-01-19T16:12:54Z

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 |subcat=Source code
 |subcat2=Tokenized BASIC
 |released=1978
 }}

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 * [http://tech.groups.yahoo.com/group/apf_consoles_and_computers/ Yahoo group devoted to APF]
 * [https://archive.org/details/APF_Imagination_Machine_1980_APF_Electronics 2-page brochure]
 [[Category:APF]]

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 == Software ==
 * [http://www.nausicaa.net/~lgreenf/apf0308.zip APF Imagination Machine emulator for Windows (Zipped download)]
-* [https://archive.org/details/apfm1000_library APF gaming console cartridges (in-browser simulation)]
+* [https://archive.org/details/apfm1000_library APF gaming console cartridges (in-browser emulation)]
 == Other links and references ==

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 == Software ==
 * [http://www.nausicaa.net/~lgreenf/apf0308.zip APF Imagination Machine emulator for Windows (Zipped download)]
 == Other links and references ==

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 * [http://www.nausicaa.net/~lgreenf/apfpage.htm Another page about APF Imagination Machine]
 * [http://tech.groups.yahoo.com/group/apf_consoles_and_computers/ Yahoo group devoted to APF]
 [[Category:APF]]

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 APF BASIC programs are stored in a tokenized format. Byte values with the high bit set (#128-#255) are used to store tokens, with "high bit clear" values (#0-#127) used for literal [[ASCII]] characters. The token meanings actually get printed out when you use BASIC commands such as PRINT CHR$(137), which causes "GOTO" to be shown (but not executed!).
-BASIC lines are separated by the carriage return (hex 0D). The first two bytes contain the line number; unlike most other BASICs which use binary integers for this, APF BASIC uses packed BCD code, where each "nybble" (half-byte) stands for one decimal digit. (Basically, if you read the hexadecimal dump of the bytes, interpret it as a decimal number with 0-9 standing for those digits and A-F never used.) Then the tokenized commands and literal characters of the program line follow.
+BASIC lines are separated by the carriage return (hex 0D). The first two bytes contain the line number; unlike most other BASICs which use binary integers for this, APF BASIC uses packed [[Binary-coded decimal|BCD]] code, where each "nybble" (half-byte) stands for one decimal digit. (Basically, if you read the hexadecimal dump of the bytes, interpret it as a decimal number with 0-9 standing for those digits and A-F never used.) Then the tokenized commands and literal characters of the program line follow.
 A program is preceded by a two-byte address pointing at the first free memory location after the end of the program, stored as a [[Endianness|big-endian]] unsigned integer, unlike the little-endian format used for addresses in most other personal computers.

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 The '''APF Imagination Machine''' was a late-1970s home computer platform. It was actually a game console with an add-on available to turn it into a full-fledged computer, with keyboard and [[Audio Cassette|tape drive]]. A [[floppy disk]] drive was also available. As with most computers of the time, it came with a version of the [[BASIC]] programming language built in.
-APF BASIC programs are stored in a tokenized format. Byte values with the high bit set (#128-#255) are used to store tokens, with "high bit clear" values (#0-#127) used for literal [[ASCII]] characters.
+APF BASIC programs are stored in a tokenized format. Byte values with the high bit set (#128-#255) are used to store tokens, with "high bit clear" values (#0-#127) used for literal [[ASCII]] characters. The token meanings actually get printed out when you use BASIC commands such as PRINT CHR$(137), which causes "GOTO" to be shown (but not executed!).
 BASIC lines are separated by the carriage return (hex 0D). The first two bytes containa the line number; unlike most other BASICs which use binary integers for this, APF BASIC uses packed BCD code, where each "nybble" (half-byte) stands for one decimal digit. (Basically, if you read the hexadecimal dump of the bytes, interpret it as a decimal number with 0-9 standing for those digits and A-F never used.) Then the tokenized commands and literal characters of the program line follow.
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 As stored on cassette with the CSAVE command, a program will be preceded by a 512-byte block taken either from bytes 0-511 or 512-1023 of memory (depending on whether memory location 41452 was set to 255 or 0 respectively), which will be placed in screen memory when the cassette is loaded (allowing the display of a title screen or instructions while the program finishes loading). Then all used memory is saved, including the program and variable values. (However, the RUN command clears variables, so if you actually want to preserve the variables loaded from tape, you need to use the GOTO command to start running the program.)
-On disk, saved BASIC program files appear to be type "S", whatever that means.
+On disk, saved BASIC program files appear to be type "S", whatever that means. (The other file type is "I", which is what data files opened by a program are.)
 == Tokens ==

← Older revision		Revision as of 16:12, 19 January 2013
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	As stored on cassette with the CSAVE command, a program will be preceded by a 512-byte block taken either from bytes 0-511 or 512-1023 of memory (depending on whether memory location 41452 was set to 255 or 0 respectively), which will be placed in screen memory when the cassette is loaded (allowing the display of a title screen or instructions while the program finishes loading). Then all used memory is saved, including the program and variable values. (However, the RUN command clears variables, so if you actually want to preserve the variables loaded from tape, you need to use the GOTO command to start running the program.)		As stored on cassette with the CSAVE command, a program will be preceded by a 512-byte block taken either from bytes 0-511 or 512-1023 of memory (depending on whether memory location 41452 was set to 255 or 0 respectively), which will be placed in screen memory when the cassette is loaded (allowing the display of a title screen or instructions while the program finishes loading). Then all used memory is saved, including the program and variable values. (However, the RUN command clears variables, so if you actually want to preserve the variables loaded from tape, you need to use the GOTO command to start running the program.)
		+
		+	On disk, saved BASIC program files appear to be type "S", whatever that means.

	== Tokens ==		== Tokens ==