[pdftex] samplepdftex.tex, pdftex-a.pdf

[Suresh Govindachar]

The page https://ctan.org/pkg/pdftex has links to samplepdftex.tex and 
pdftex-a.pdf. Some questions about these files:

1) I can't find them inside my install of Miktex. Why doesn't an update 
of Miktex result in installing these files on my computer?

2) To generate a version of pdftex-a.pdf on letter-sized pages, I looked 
for pdftex.tex, but could not find it. Where is the source for 
pdftex-a.pdf?

3) I downloaded samplepdftex.tex and attempted to generate a pdf, but 
got the error shown below. How can this be fixed or is samplepdftex.tex 
not meant to be compiled into a pdf?

     This is pdfTeX, Version 3.14159265-2.6-1.40.21 (MiKTeX 20.6.29 32-bit)
     entering extended mode
     (samplepdf.tex 
(c:\opt\miktex_2.9\tex/generic/pdftex\pdfcolor.tex){C:/Users/sgo
     vindachar/AppData/Local/MiKTeX/2.9/pdftex/config/pdftex.map} [1] [2
     Position: X=4736286sp, Y=28455731sp.
     ! pdfTeX error (ext5): cannot open file for embedding.
     \plainoutput ...headline \pagebody \makefootline }
                                                       \advancepageno 
\ifnum \out...
     <output> {\plainoutput
                            }
     \break ->\penalty -\@M

     l.481 \newpage

     !  ==> Fatal error occurred, no output PDF file produced!
     Transcript written on samplepdf.log.

Thanks,

==Suresh