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Changes To A Field Guide to PDP-8 Assemblers
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Changes to "A Field Guide to PDP-8 Assemblers" between 2018-01-27 14:31:03 and 2018-01-27 14:41:25

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### <a id="ralf" name="flap"></a>RALF/FLAP

RALF is the back-end assembler for OS/8's FORTRAN IV compiler. As a result of that support role, it has a few primary advantages over PAL8:

*   relocatable output code

*   easy access to the optional [floating-point processor](http://dustyoldcomputers.com/pdp12/fpp12.html)
*   easy access to the optional [floating-point processor][fpp12]

The RALF assembler has a mode switch that causes it to generate absolute-addressed code, as PAL8 does. In this mode, it is called FLAP.

The FPP modes are the key advantage of RALF/FLAP. Vincent Slyngstad [suggests][smal8] that you think of these as assemblers for the FPP rather than for the PDP-8.

**INCOMPLETE**

[fpp12]: https://archive.org/details/bitsavers_decpdp12DE_2606247


### <a id="sabr"></a>SABR

As RALF is to OS/8's FORTRAN IV compiler, so the [Symbolic Assembler for Binary Relocatable programs](http://homepage.cs.uiowa.edu/~jones/pdp8/faqs/#langs) is to OS/8's FORTRAN II compiler.

SABR is a relative assembler, unlike PAL8 or FLAP, meaning that the OS/8 linking loader (`LOADER.SV`) adjusts all of the addresses in the assembled `*.RL` output to their final values.
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