The answer is ....
after calling the North American toll-free help number for Ricoh imaging, and waiting a while, and dealing with someone who actually took some time to understand the issue, she (the telephone CSR) got through to an imaging engineer, who (apparently) said something along the lines of "that's so odd", and directed her to an archived version of firmware v1.02. Unfortunately, that website was not available on the open internet, and the CSR could not reach the site (only the standard English page on the .jp domain, which of course only has the most current version), and she would not give the URL to me to try it myself. After another conference between the CSR and the engineer, it was his/her(?) considered opinion that the lack of v1.01 on the list of updatable models was simply a years-old oversight. After verifying that I really had a K5, I was advised to cross my fingers and try it. It worked.

Here's to hoping I'm the last person with v1.01 firmware who actually Reads The Friendly Manual. I suspect that if there is a v1.17 update, the readme will not have been updated at the source.

@JAK - I've bricked enough hardware, my own and clients', to have developed a serious habit of reading the documentation, and when finding something that indicates my hardware is NOT UPDATABLE, to not proceed.

having worked with software and hardware updates for decades, I can assure you, that long list of version-by-version changes is just incremented with each release (that's it's pupose - so the devs can go back and see when a change was implemented). In other words, the reference to v1.01 is something that appeared when v1.02 was released, and has not been examined since.

I'm simply not willing to bet my camera that v1.01's exclusion from the list of updatable models from the current firmware release is just an oversight. I'd prefer to wait until someone who actually knows what's going on with the firmware, or who can credibly ask someone who does, before I pull the trigger.

And while I'm here, thanks for your attention to my problem

Thank you. I have contacted JPS, via their website contact form. I'll let you know if they get back to me.

Thanks to davidwozhere, johnriley, and JAK for making the effort to understand the question.

and yes, JAK -- I see I was unclear. The camera is a K-5. I attempted to be "conversational" and messed up by failing to include the apostrophe between the "K-5" and the possessive, "s". Any way to edit the post to make it clearer for anyone searching the forum(s) for a similar issue?

johnriley says "...an enquiry to JPS would perhaps be the absolutely safest way to go. Why not give them a ring and ask? "

I'm totally not into bricking my camera with a firmware upgrade after RTFM and ignoring the instructions, BUT, I'm also a total newb here (and I live on the west coast of Canada) -- who/what are JPS, and how do I find them?

Thanks in advance!

I want to update my K-5s firmware.

I have downloaded the firmware v1.16.

My camera has firmware 1.01.

This is what the readme file says:
===========================================================================
PENTAX K-5 Firmware Updating to Version 1.16
===========================================================================

* Firmware is the software that runs inside digital cameras.

Updatable models
K-5 digital SLR cameras running Firmware Ver. 1.00/1.02/1.03/1.10/1.11/1.12/1.13/1.14/1.15

--
As you can see 1.01 is not included in this list of updatable models.
Where can I get firmware 1.02?