This is what I call an amazing find. Behind an unassuming German language listing on eBay hid a Sanyo programmable calculator that is unlike any other I've seen to date.

Superficially, it reminds me of the Commodore PR-100 but there are some crucial differences. On the negative side, this calculator has a lot fewer functions than the PR-100; no hyperbolic functions, no statistics, no probability, no coordinate conversions, no metric conversions. On the plus side, (and this is a huge plus!) the CZ-0911PG has a partially merged programming model; the second function [F] key is combined with the next keystroke as a single step in program memory. This makes a major difference when trying to squeeze complex algorithms into the calculator's limited program memory.

Another unusual feature of this calculator is its unique battery tray; the battery holder for four "AA" batteries can be removed in its entirety, to be replaced by a rechargeable battery pack. Very elegant.

The partially merged programming model of this calculator allows for a fairly accurate implementation of my programming favorite, the Gamma function. The program presented here calculates the natural logarithm of the Gamma function to at least 8 digits of precision for any real argument except for negative integers:

00  11	-
01 101	1
02  55	SM
03 101	1
04 106	6
05  64	x-y
06  11	-
07 106	6
08  80	=
09  62	+/-
10  52	M×
11 101	1
12  11	-
13 105	5
14  64	x-y
15  80	=
16  96	SKIP
17  93	GOTO
18 100	0
19 106	6
20  11	-
21 105	5
22  64	x-y
23  80	=
24  12	×
25  55	SM
26 100	0
27  40	ln
28  11	-
29  56	RM
30 101	1
31  40	ln
32  11	-
33  56	RM
34 100	0
35  10	+
36  81	(
37 102	2
38  12	×
39  65	π
40  12	×
41  56	RM
42 100	0
43  82	)
44  19	√
45  40	ln
46  10	+
47  81	(
48 103	3
49 105	5
50  17	1/x
51  13	÷
52  56	RM
53 100	0
54  18	x2
55  11	-
56  70	.
57 101	1
58  13	÷
59  56	RM
60 100	0
61  18	x2
62  10	+
63 103	3
64  13	÷
65 103	3
66 106	6
67  13	÷
68  56	RM
69 100	0
70  80	=