FORTH for the SHARP PC-E500 (S)

[robve]

(10-10-2021 09:11 AM)Klaus Overhage Wrote:  And there is always an exception #-28 for "user interrupt", which is not so nice. Is it possible to use another key especially for WORDS, for example C-CE, for normal exit without exception?

Good idea! This can also improve a break from FILES.

With respect to your issue with BRK from WORDS, a debounce loop is used. I'm curious what the problem could be. I have not had this problem. Perhaps the timing of the second BRK bounce exceeded the debounce timing, implemented as follows:

Code:

break__:        local
                pre_on
lbl1:           mv      il,$ff                  ; Test if the break
lbl2:           test    ($ff),$08               ; key was intentionally
                jrnz    lbl1                    ; released
                dec     i                       ; (break action is triggered
                jrnz    lbl2                    ; when the break key is released)
                pre_off
                endl
                mv      il,-28                  ; User interrupt

test ($ff),$08 sets the z flag if BRK is not pressed. The debounce time is 4.3ms (13x255 cycles), which is rather short. A typical debounce time is 20ms or longer. Increasing the timing to 20ms should help. Also the inner jrnz lbl1 was changed to reset the debounce counter when a key bounce/hit reoccurs.

With respect to Forth source file loading time, a relatively large file such as debugger.fth should take no more than about 30 seconds to compile with the new FIND-WORD. This can be further reduced to a couple of seconds, but this requires a redesign of the dictionary. A simple approach is the HP-71b implementation, which does not offer WORDS (or similar). This simplifies the search, because the order of dictionary words does not need to be preserved across the entire dictionary, only the relative order of words with the same name length. A hybrid approach could work well: limit WORDS to only list the user-defined words (and words loaded with INCLUDE). Built-in words are searched by name length to speed up compilation. This hybrid approach works with FORGET and MARKER, and does not require memory to store trees. Adding a small index table to search built-in words suffices. However, WORDS will not show the built-in words.

- Rob