Dunno.   The first I dealt with was the f77 based on the pcc backend.

From: TUHS [mailto:tuhs-bounces@minnie.tuhs.org] On Behalf Of ron minnich
Sent: Tuesday, March 7, 2017 1:14 PM
To: TUHS main list
Subject: Re: [TUHS] fortran compiler, in assembly, for pdp-11

I was not clear, evidently, although part of this is my memory's fault :-)

There was a fortran compiler on v6, written in assembly. I was wondering who wrote it.

On Tue, Mar 7, 2017 at 9:34 AM ron minnich <rminnich@gmail.com> wrote:

I spent a year or so working on this in 1977. I was wondering who wrote it.

Funny but: I once had a compile fail on Motorola's MPL compiler, which was written in fortran. It had so many continued comment lines that the 16-bit column number went negative, and I got a fairly obscure error. 

Anyone remember who wrote it?