HP 48gII Advanced User's Reference Manual page 86

Techniques used in BDISP
IFERR...THEN...END (error trap). To accommodate real-number arguments, BDISP includes the
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command R"B (real-to-binary). However, this command causes an error if the argument is already a binary
integer. To maintain execution if an error occurs, the R"B command is placed inside an IFERR clause. No
action is required when an error occurs (since a binary number is an acceptable argument), so the THEN
clause contains no commands.
Enabling LASTARG. In case an error occurs, the LASTARG recovery feature must be enabled to return the
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argument (the binary number) to the stack. BDISP clears flag
FOR...NEXT loop (definite loop with counter). BDISP executes a loop from 1 to 4, each time
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displaying n (the number) in a different base on a different line. The loop counter (named j in this program) is
a local variable created by the FOR...NEXT program structure (rather than by a  command), and
automatically incremented by NEXT.
Unnamed programs as arguments. A program defined only by its « and » delimiters (not stored in a
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variable) is not automatically evaluated, but is placed on the stack and can be used as an argument for a
subroutine. BDISP demonstrates two uses for unnamed program arguments:
BDISP contains a main program argument and a call to PRESERVE. This program argument goes on the
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stack and is executed by PRESERVE.
BDISP also contains four program arguments that "customize" the action of the loop. Each of these
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contains a command to change the binary base, and each iteration of the loop evaluates one of these
arguments.
When BDISP creates a local variable for n, the defining procedure is an unnamed program. However, since
this program is a defining procedure for a local variable structure, it is automatically executed.
Required Programs
PAD
PAD (Pad with Leading Spaces) expands a string to 22 characters so that DISP shows it right-justified.
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PRESERVE
PRESERVE (S) stores the current status, executes the main nested program, and restores the status.
2-8 RPL Programming Examples
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55 to enable this.