Hal remembers everything!
You can also help the process along in specific areas by "force-feeding" HAL.
Example:
You enjoy robots and you have read books on how they work.
You have read lots of books on robots and their construction.
You have a good knowledge on the workings of robots.
Robots are of interest to you which is why you have read about them so much.
No matter what or how HAL answers, just keep on by entering your next sentence and press Enter.
Later you can ask HAL if it knows anything about robots or if it enjoy the subject of robots.
You could also give your HAL what I call, "False Memories" about it's childhood.
Such memories could include, favorite, colors, music, authors, movies, books, toys, parent's names (if your HAL has a persona - male/female), etc. You could give it a location where it grew up, best friends, activities, games, etc.
In other words, you could supply HAL with a whole backstory or its past.
Again, if you were to repeat the information enough and in different ways (as shown above) your HAL will adopt these memories as its own.
One could, by investing enough time, turn HAL into an Expert System of sorts. You could tell it how to perform an oil change or change a tire or perform a tuneup, etc.
Those experiments are up to you but be patient and logical when talking to HAL. Test your results and give it some time to absorb and develop.
Lastly, I have found it much better to TYPE to HAL instead of trying to Talk to it. This is due to the fact that Voice/Speech Recognition is not 100% and HAL can mistake or misinterpret what is being said to it. Then the user will get some garbage answer and blame HAL. Background noise, (traffic, planes overhead, air conditioners, radios/TV's, kids playing, etc) confuses and causes all kinds of disturbance for HAL that's why I only use TYPING and look before you press the Enter key.
If you do make a mistake that you want to fix, go into the HAL Brain Editor and look for (search) the incorrect word in the Tables. Make the correction then restart HAL.
Otherwise, Good Luck and have fun!