PiDP-8/I Software

Update of "Running FOCAL,1969"
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Artifact ID: 564ddf71d3da515216c285efaa53ccff96613857
Page Name:Running FOCAL,1969
Date: 2019-08-16 00:27:47
Original User: tangent
Next 32ed2c465d7b18a8d8ec549316607938ccd67637

The PiDP-8/I project defaults to U/W FOCAL, but it has an option that lets you either add FOCAL,1969 to this or switch to it by disabling U/W FOCAL entirely:

$ ./configure --enable-os8-focal69 --disable-os8-uwfocal

Once that software is built and installed, you might then wonder, "How do I get started?" This document is our answer to that question.

Running Programs with OS/8

OS/8 is not like Unix or DOS or any other OS that has a command PATH. The first word in an OS/8 command is handled by the OS/8 keyboard monitor (i.e. that which handles responses to the "." prompt) so it has to be an OS/8 keyboard monitor command. In other words, OS/8's keyboard monitor does not search for *.BN, *.SV and similar files on disk and treat them as top-level command names. See page 1-35 in the 1974 edition of the OS/8 Handbook.

The optional CCL feature of OS/8 extends the Keyboard Monitor with more commands, some of which add aliases for running binaries that makes it work more like Unix or DOS (e.g. "TECO"), but don't get confused about what's going on here. (See page 1-52 in the OS/8 handbook for more on CCL.)

If you want a Unix analogy, it's as if OS/8 has nothing but shell built-in commands, no external commands. To run a binary on disk, you have to get at it through one of the shell commands — that is, Keyboard Monitor or CCL commands — or one of the commands you can get to via such commands.

Starting FOCAL,1969

I've taken the time to go into all of that detail because it explains why none of the following commands start the FOCAL.BN binary we ship when you build the OS/8 disk packs with FOCAL,1969 enabled:


What you actually want is to start the OS/8 absolute binary loader, which is what handles *.BN files such as FOCAL.BN:


The /G option means "go," starting the program immediately after loading it into core memory.

You'll get another "*" prompt after that, but it's from FOCAL, not ABSLDR. See page 1-108 in the OS/8 handbook linked above for more detail about ABSLDR commands.

Returning to OS/8 from FOCAL,1969

Say "L" (LOGICAL EXIT) at the FOCAL * prompt to get back to OS/8. Unlike U/W FOCAL, FOCAL,1969 does not do this on Ctrl-C.

Using FOCAL,1969

There are several freely-available PDF documents for DEC FOCAL which apply to varying degrees to what we ship. We recommend reading them in this order:

On Naming

You might be wondering about our use of the name "FOCAL,1969". That's because that's how the software identifies itself on starting up. It refers to a fairly specific version of the software, which matches what we distribute. It is sometimes also called "FOCAL 69", though that term was not favored by DEC.

Another name that was favored by DEC marketing is "FOCAL-8." This is a generic name not referring to any specific version of FOCAL. You can read it as "DEC FOCAL on the PDP-8."

There were many variants of FOCAL back in the day, some from DEC and some from outsiders. Because the language was never formally standardized, and there never was one dominant version, it can be useful to be specific about which variant you're talking about. Generic terms like "FOCAL", "FOCAL 69", or "FOCAL-8" should be used only when you're not trying to refer to a specific version.