RPN-38 Extended — Making the HP-38 user-friendly

What's new in RPN-38 CX

Due to the limited hardware capabilities available to engineers in the late 70's, a number of compromises had to be applied to the design of the HP-38. For example, since storage area was especially scarce in those days, users had to choose between many registers and only a few program lines, or vice versa. For every 7 lines of program one register had to be sacrificed.

Editing a program was cumbersome, to put it mildly. To insert a missing line, a branch to an unused line had to be entered,the line just overwritten had to be re-entered at the target location, followed by the missing line, followed by a branch back to the line after the original branch. Since branches always addressed line numbers, changing a program usually involved fixing various branch commands.

Deleting a line was not supported. You replaced the line to be deleted by a GTO command to the following line instead.

RPN-38 CX fixes the most glaring shortcomings of the HP-38



Allocation Storage registers share memory with program lines 20 registers and 99 program lines available at all times
Registers STO register arithmetic limited to registers 0...6. STO and RCL register arithmetic supported by all 20 registers.
Also works with LASTx, e.g. RCL + ENTER
Program notes Not available Title, description, date
Editing Overwrite next line only Insert, delete line with automatic branch correction
Storing Not available Quickly store and retrieve any number of programs
Sharing Not available E-mail, print, Dropbox, and more
Prefix keys Active if pressed Active if pressed. Deactivated if pressed again. Indicators show state.
Register view Not available All registers shown on single screen including formatted display.
Run/Stop and single-step program without leaving register view.
Program view Not available Entire program including title and description. Supports deleting any line by swiping.
Shortcut keys

Not available. Two key presses required for commands like SST, GTO, P/R.

Available for P/R, SST, BST, GTO, DEL, NOM, and EFF.
Decimal Point,
Thousands separator

Fixed to "."
Thousands separator shown as comma

User-selectable representations
Command display

Not available

In program mode or while single-stepping, current command is shown as text below display
Current step display

Not available

Current program step is shown below display
Program memory fill status

Not available

Red progress bar shows amount of program memory filled

Optional shortcut keys:

Additional Features

More features only RPN-38 CX offers:

    Getting data into RPN-38 CX
    You can preset RPN-38's registers with data created externally without having to type them in.
    Simply prepare the data in text format in any app that can handle text, like Notes, Mail any many others. Then copy the text and paste it into RPN-38's display in Run mode.
    The data format looks like this:
    Memory registers:
Rn or R.n value count
where n = 0…9
value is the number to be stored
count is the optional cash-flow count
    Top-row registers:
fn value
where fn = n or i or PV or PMT or FV
value is the number to be stored
    Cash-flow 20:
FV value count
value is the number to be stored for CF20
count is the optional cash-flow count for CF20
Alternatively, the count may set by:
N20 value
To set R1 = 4.5, R6 = 6.28E-7, R.3 = 439, PV = 1000, and i = 5 prepare your data like this:
    R1 4.5
R6 6.28e-7
R.3 439
pv 1000
i 5
    Select all of the text and paste.
Upper-/lower-case is ignored.
One or more blanks or tabs may follow the register number.
M may be used in place of R.
R.n may also be written as R1n, e.g. R.3 is the same as R13.
The order of the registers is irrelevant.
Unlisted registers are left untouched.

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