Tuesday, 19 January 2016

Minol Completed

Well, it’s sort of finished and working, probably. I added the final bits this morning.

  1. I added a marker in RAM (a 32 bit value) that if present indicated memory already had a MINOL program in there – if this isn’t present it does a NEW on start, otherwise it leaves it alone. You can switch back and forth from MINOL and the Monitor at will. 
  2. Ctrl+C now interrupts at Print statements. 10 PR "HELLO WORLD":GOTO 10 previously could only be got out of using the RESET button.
  3. It looks for the stack top rather than assuming it’s there (it was previously hard coded to $0FF8). It should run with only 2 x 6810 RAM chips (e.g. $C00-$CFF) in the main board, except that a long typed in instruction won't work (the keyboard buffer and stack will collide). It really needs at least three ($C00-$D7F)
  4. The current line number is cleared when you type in a keyboard command. (this was a bug), meant that if you typed PR 1/0 in the command line the number given was the last line number executed.

I will update the released version so it has both ROM images in it sometime soon, e.g. it boots into MINOL, you can type MINOL programs into it and so on. It's not bad, the original code was 1.75k this is about 2.5k but most of the difference is because of the screen driver.

The next bit is to write the code to translate a text file to MINOL format – may do something automatic with line numbers ? – and get that loading in.  You can type in programs like we used to with C64 and Speccys, it does work, but it's not a good idea on a beta langiage. I remember writing about my experiences with such earlier.

Then, once that’s done, look at Star Trek. I think there are three Star Trek related retrochallenges this half-year :)

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