Latest version running PHP 5.1.6

Simple question, hard to find the answer. What is the latest version of zencart that supports PHP 5.1.6? I don't have the option to upgrade PHP at this point in time.

The current version, 1.3.9h, should run fine on it.

hm, well I read on another thread that an error i was receiving was down to not having php 5.3. The error is that when we go to edit a product, it blanks out the title and some of the other information in the form. Thus loosing information about the product.

I suspect that you're referring to the tweaks needed and explained in this post.

It's better to make these changes to 1.3.9h than to drop back to an earlier version and introduce known security vulnerabilities, exacerbating the risks you're already taking by running a version of PHP with known problems.