This Taiwanese programmable calculator (remember when so many electronic gizmos used to be made in Taiwan? Not anymore; most are made in China nowadays) is yet another OEM machine containing the same chipset as the Citizen SR-59. What chipset it is, I have yet to find out; the machines I was able to open up had unmarked chips inside. Probably Toshiba.

Although the PSR-98 has conditional and unconditional branch instructions, its programming model is nevertheless somewhat simplistic. The most significant limitation is that jump destinations are limited to within nine steps of the current program location. There's also no ability to view or edit programs, making the programming process more cumbersome than it ought to be.

The programming example I wrote for this machine doesn't use branch instructions, however. It is a straightforward implementation of the logarithm of the Gamma function using the Lanczos-approximation. In addition to using 43 of the machine's 45 program steps, it also requires that you enter four constants into the calculator's memory registers; what you get in return is an algorithm that computes the result to 8+ digits of precision:

STO 3: 2.5066284644
STO 4: 41.41740453
STO 5: -27.063892494
STO 6: 2.2393179633

MS
+/-
-
3
.
1
5
+
+/-
ln
×
(
MR
-
.
5
)
+
(
RCL
3
+
RCL
4
÷
MR
+
RCL
5
÷
1
M+
MR
+
RCL
6
÷
1
M+
MR
)
ln
=