From mboxrd@z Thu Jan  1 00:00:00 1970
From: pnr@planet.nl (Paul Ruizendaal)
Date: Wed, 8 Nov 2017 23:02:01 +0100
Subject: [TUHS] pre-more pager?
Message-ID: <38D56F21-9AF6-4A00-995F-DAAD6570BC51@planet.nl>

> 
> Regarding the links and old bsd's. The binary cr3 on 1bsd works in v7. 
> Also, the book I'm reading has a c program that does paging. But, I'm 
> always off down the rabbit hole... I tried to compile the cr3.c source 
> and I get this error:
> 
> # cc cr3.c
> Undefined:
> _fout
> _flush
> _getc
> _end
> 
> My understanding is that cc includes libc by default, so these must not 
> be in libc. But getc is standard lib, so what am I missing?

That source is for V6 not V7. V6 did not have the stdio lib yet, but a precursor to that.
The binary you are using has the older io routines statically linked in.

Paul