The undocumented syntax of Extended Color BASIC



The other night I was experimenting with Extended Color BASIC and the “GET” and “PUT” commands. I knew that the documentation was incorrect about them, and was trying to figure out how they worked. I also wanted to do this without cheating (i.e., doing a quick web search and finding the results of someone who already did this).

I will share the results of this experimentation later, but I wanted to pass along something I was unaware of until last night. I ended up looking at the Extended Color BASIC disassembly to try to find clarification on why something I was seeing was happening. Reading through it revealed a syntax I was unaware of for the following commands:

  • CIRCLE
  • GET
  • LINE
  • PAINT
  • PUT

Much like the CoCo BASIC “PRINT@” command, the ‘@’ sign is allowed on these commands as well. It does nothing, and is merely skipped:

Extended Color BASIC’s unused @ syntax.

A note in the Unraveled book says:

It is interesting to note that the “@” symbol does not do anything! It is there to make the command syntax consistent with the “PRINT @” concept and to make it compatible with other versions of Microsoft BASIC.

– Extended Color BASIC Unraveled II

Since this was not documented in the manual (as far as I know), I was not aware of this syntax.

Did you know about this?

There are certainly many undocumented secrets in the Color BASIC ROMs, from the unimplemented Easter egg to things like how the PLAY command plays nonexistent notes. Certainly the author of the Unraveled series discovered these items, and anyone who read those books would have known about it, but I wonder how widespread these oddities were back in the 1980s.

Until next time…

6 thoughts on “The undocumented syntax of Extended Color BASIC

    1. Allen Huffman Post author

      HLINE@(x,y) works. I bet they just parsed the H, then made use of the parameter parsing of the existing code. I expect the others will work as well.

      Reply
  1. Pingback: TIL: Color BASIC device numbers and more. | Sub-Etha Software

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