HP Forums

I found a sort of tricky but useful way to temporarily reassign keys
on the HP-30b. Normal key assignment is easy using program step 0,
and all keys except a few critical ones (reset, ON/CE, INPUT,etc.) are
reassignable, this includes the numeric keys. The 30b is a macro
programmable machine in the sense that keys executed in a program act
as if they were pressed on the keyboard. In particular there's no
automatic ENTER for a numeric key, so a program can be used to enter a
digit in the middle of a number, for example. Making use of the above
two features along with a conditional that doesn't need to use the
stack at all (DSE and ISG) allows for temporary reassignment of keys.

The following code demonstrates this for a program that was suggested
in this thread

Mode:	RPN

Fix:	0

Shift-Hold 0 starts/resets Sudoku entry mode showing digits 1-9 available.

Pressing digits 1-9 will remove that digit from the display.

When all digits have been pressed 0 is shown and Sudoku mode ends

allowing normal calculator use.   Sudoku mode can also be ended by

storing 0 in register 0, this is possible since the 0 key is not redefined.



Registers used:

0 - indicates mode, if greater than 1 then Sudoku mode else calculator mode

6 - 10 ^ (number of digits in new digit string)

7 - new digit string

8 - old digit string

9 - user entered digit

Prog 0:

0	SH0

1	2

2	STO 0

3	1

4	2

5	3

6	4

7	5

8	6

9	7

10	8

11	9

12	STO 8

13	Sudoku

14	RTN

15	Lbl 00

16	DSE 0

17	Gto 01

18	RTN

19	Lbl 01

20	STO 9

21	0

22	STO 7

23	1

24	STO 6

25	Lbl 02

26	RCL 8

27	Input

28	GF 03

29	1

30	0

31	/

32	Math	| IP

33	Up	|

34	Up	|

35	=	|

36	STO 8

37	Ans

38	Math	| FP

39	Up	|

40	=	|

41	1

42	0

43	*

44	RCL 9

45	?=	

46	GT 02

47	Rv

48	STO + 7

49	1

50	0

51	STO / 7

52	STO * 6

53	Gto 02

54	Lbl 03

55	RCL 6

56	STO 0

57	RCL * 7

58	STO 8

59	Sudoku

60	RTN

bytes.checksum: 103.018

Prog 1:

0	1

1	1

2	Gto 00

Prog 2:

0	2

1	2

2	Gto 00

Prog 3:

0	3

1	3

2	Gto 00

Prog 4:

0	4

1	4

2	Gto 00

Prog 5:

0	5

1	5

2	Gto 00

Prog 6:

0	6

1	6

2	Gto 00

Prog 7:

0	7

1	7

2	Gto 00

Prog 8:

0	8

1	8

2	Gto 00

Prog 9:

0	9

1	9

2	Gto 00

-Katie

Nice trick, but no more room for more programs. :(

There's not a lot of room for program in this calculator at all. It's very close to the 12C in actual programming space because it's not space efficient in merging program steps.

However, in this case only about 50% of the total program space is used and you could add more programs to this code. Accessing them from arbitrarily reassigned keys wouldn't be possible but you could use the DSE/ISG mechanism as a means to branch to different programs by LBL. For example storing a 3 in register_0 could would indicate the program A should be run when Shift-0 was pressed, a 4 in register_0 would indicate program B, etc..