Is Small-C 1.1 public domain ?
Small-C was published in the US before January 1988.
Small-C source code doesn't have a Copyright statement.
I can't find the original May 1980 issue #45 of Dr. Dobb's Journal.
The re-print article in 1982 Volume 05 is clearly copyrighted.
February 1976 issue of DDJ states that articles may be reprinted for any non-commercial purpose.
All the derivative versions of Small-C that I found are copyrighted.
So the answer is: I doubt that 1980's DDJ's copyright terms were more liberal than 1982 or 1976 ones. So, no, Small-C 1.1 is not public domain!
https://github.com/trcwm/smallc_v1
https://en.wikipedia.org/wiki/Berne_Convention_Implementation_Act_of_1988
Copyright© 1982 by People’s Computer Company. All rights reserved. No part of this book may be reprinted, or reproduced, or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage and retrieval system, without permission in writing from the Publisher.
Copyright 1976 by People's Computer Company
Reprint privileges
Articles herein that are copyrighted by individual authors or otherwise explicitly marked as having restricted reproduction rights may not be reprinted or copied without permission from People's Computer Company. All other articles may be reprinted for any non-commercial purpose, provided a credit-line is included. The credit-line should incidate that it was reprinted from DR DOBB'S JOURNAL OF COMPUTER CALISTHENICS & ORTHODONTIA, and include our address.
http://cini.classiccmp.org/pdf/DrDobbs/DrDobbs-1976-02-v1n2.pdf
https://web.archive.org/web/20060318052012/http://www.ddj.com/ftp/2006/200601/ddjfirstissue.pdf