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| **Introduced** | 1965
| **Manual** | [PDF, 790 kB](http://www.telegraphics.com.au/doc/paliii.pdf)
| **Delivery** | paper tape
The PAL-III assembler shipped on [punched paper tape](https://en.wikipedia.org/wiki/Punched_tape) as part of the grandiosely-named "PDP-8 Assembly System." This amounted to an assembler, an editor, a debugger, and a loader, each a separate paper tape. The programmer would first toggle the RIM loader into the PDP-8's front panel, then use that to load the BIN loader from yet a fifth paper tape, then run each of these tapes through the paper tape reader repeatedly — reusing the still-in-core BIN loader each time — in order to iterate his way toward a working program!
The assembler required at least two passes through the tape reader in order to produce a computer-readable BIN format output tape, and up to four depending on the additional output options the programmer wanted, such as a listing on the terminal.
The assembler tape required at least two passes through the tape reader in order to produce a computer-readable BIN format output tape, plus an optional third pass if you wanted a human-readable listing on the terminal.
If you look at pictures of PDP-8 computers, you can often see a tray with narrow slots in it, each meant to hold one of these key paper tapes, as they were needed near at hand when using the computer. There is a good picture of a blue one on [the cover of the 1974 edition of the OS/8 Handbook](https://archive.org/stream/bitsavers_decpdp8os8_39414792/OS8_Handbook_Apr1974?ui=embed#page/n0/mode/1up).
PAL-III can be considered the baseline assembler for a PDP-8, since almost every PDP-8 at least included some kind of paper tape reader, and most of the other assemblers surveyed here share its basic syntax.
## MACRO-8
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### PAL8
PAL8 understands the same basic language as PAL-III and generally has more features, most especially related to running under OS/8, such as the ability to set options via OS/8's command interpreter (CCL) rather than via the PDP-8's front panel switches.
I consider it the default assembler for OS/8 users. If none of the information below guides you to one of the other assemblers, you should probably start with PAL8. If you have a piece of assembly code that is meant to be assembled under OS/8, and you have no evidence that is for any other assembler, it's probably meant to be assembled by PAL8.
PAL8 has several features not present in PAL-III:
PAL8 has many features not present in PAL-III:
* automatic link generation for off-page references
* it can output [CREF and DDT][os8m]-compatible output files
* in addition to `+` and `-` in expressions, it allows:
* `^` for 12-bit unsigned multiplication (`*` was already taken for setting the location counter)
* `%` for 12-bit unsigned division (`/` was already taken as the comment start character)
* `!` for Boolean OR (the ASR-33 terminal supported [a 64-character subset of printable ASCII](http://iclces.uk/articles/a_teletype_font.html), which did not include ¦)
* `!` for Boolean OR (the ASR-33 terminal character set [did not include the ¦ character](http://iclces.uk/articles/a_teletype_font.html))
* `&` for Boolean AND
* literals in the current page via `(NN` syntax (closing paren optional) or in page zero via `[NN`
* single-character ASCII constants: `"A`
* more pseudo-operations:
* `DEVICE`, `FILENAME`, and `TEXT`: insert 6-bit packed ASCII text strings in the output
* `DTORG`: set DECtape block number in typesetting output
* `EJECT`: emit a form feed in the listing output; optionally set a new header line
* `IFDEF`, `IFNDEF`, `IFZERO` and `IFNZRO` with angle brackets for conditional assembly
* `PAGE`: [re]set the page part of the location counter
* `NOPUNCH` and `ENPUNCH`: stop and restart binary output
* `RELOC`: assemble code for relocation after loading
* `XLIST`: suppress part of the listing output
* `ZBLOCK`: reserve memory, setting initial values to zero
PAL-III has a few features not implemented in PAL8:
* the ability to get a brief listing of the undefined symbols in a program
PAL8 is missing one feature present in PAL-III: the ability to get a brief listing of the undefined symbols in a program. The information is instead presented inline in the listing output, not grouped together into a single place, which can make refinement of an in-development program tedious as you need to comb it out of the other output.
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