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CLOCK LISP: A 1986 Analogue Clock for AutoCAD

September 18, 2020

Last updated July 28, 2026

Every library has one thing in it that is not really a tool. This is that thing. CLOCK draws an analogue clock face in your drawing, with hands set to the current time and the date spelled out.

It is dated January 1986 and credited to Kelvin R. Throop, which is a pen name rather than a person — a stock pseudonym borrowed from science fiction magazines and used by more than one author over the years. Whoever was behind it, the file is older than most CAD departments.

What it actually is

Open the file and the first thing you meet is a long list of numbers. That list is the clock face — every line and arc of the bezel, the case, the numerals and the stand, stored as a run of coordinates with a code in front of each telling the routine whether to move to that point or draw to it.

That is a vector font or a plotter file, essentially, embedded in an AutoLISP program. In 1986 that was a perfectly sensible way to store artwork: blocks and DWG references were awkward to distribute, and a list of numbers in a text file travelled anywhere. It is also why the file is only a couple of kilobytes for something that draws a detailed object.

The month names are stored the same way, as a plain list, so the date can be written out in words rather than as numbers.

Why it is worth two minutes

Not as a drawing tool — nobody needs a clock on a floor plan. It is worth looking at for two other reasons.

The first is that it is a clean, readable example of the coordinate-list technique, which still has uses: company logos, north points, standard symbols that have to be drawn rather than inserted. If you have ever wondered how to get artwork into a routine without shipping a block library alongside it, this is the answer in its simplest form.

The second is that it reads the system clock and does something with the result, which is the same mechanism behind date-stamping a title block or writing a plot date into a drawing. Here it is doing something frivolous, which makes it easier to follow than a production routine would be.

Command reference

The file defines a single command, CLOCK.

Note that the clock is drawn once with the time as it was when you ran the command. It is a picture of a moment, not a running clock — it will not tick.

How to load it

Unzip Clock.zip and load CLOCK.LSP with APPLOAD. There are no support files, and this is not one for the Startup Suite. Our AutoLISP guide covers loading.

Step-by-step usage

  1. Open a scratch drawing. This draws a clock, which you probably do not want in live work.
  2. Type CLOCK.
  3. The clock face appears with the hands at the current time and the date written out.
  4. Zoom to extents if you cannot see it — the coordinate list uses its own scale, so where it lands depends on your drawing.

Compatibility notes

1986, which puts it among the oldest files on this site alongside the slot routine. Written-for rather than tested-on by four decades. That said, it does nothing exotic — it reads a system variable, walks a list and draws lines — so it stands a reasonable chance of still working.

Plain AutoLISP with no dialog boxes and no Express Tools calls, so nothing requires the full product; LT users on LT 2024 or later, the release that brought AutoLISP to LT, should be able to run it. See what runs on AutoCAD LT.

Download

Name: CLOCK
Description: A refined analogue clock for AutoCAD.
Type: AutoCAD AutoLISP Routine
Author: Kelvin Throop
File Size: 2 Kb
Cost: Free
Worked on: AutoCAD
Download File: Clock.zip

Related routines

  • SLOT — the other 1986 file in this library, and an actually useful one.
  • ATEXT — another routine that computes positions around a circle.
  • Best of LISP collection — more code worth reading.

References

  • AutoLISP: the complete guide
  • Free LISP routines library
  • AutoLISP Lesson 9: Data Structures
  • AutoLISP on AutoCAD LT

Filed Under: AutoLISP Routines

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