\catcode`-=11
% Roman
\font\berkeley-roman-roman=pbyk8r
\font\berkeley-roman-medium=pbym8r
\font\berkeley-roman-bold=pbyb8r
\font\berkeley-roman-black=pbyc8r

% Italic
\font\berkeley-italic-roman=pbyko8r
\font\berkeley-italic-medium=pbymo8r
\font\berkeley-italic-bold=pbybo8r
\font\berkeley-italic-black=pbyco8r

% Slanted
\font\berkeley-slant-roman=pbyki8r
\font\berkeley-slant-medium=pbymi8r
\font\berkeley-slant-bold=pbybi8r
\font\berkeley-slant-black=pbyci8r
\catcode`-=12

\newcount\fontvariant \newcount\tmpVariant
\newcount\fontstyle \newcount\tmpStyle
\newcount\fontface 

\fontvariant=0 \fontstyle=0 \fontface=0

\def\dftsize{15pt} % default font size
\def\ftsize{15pt}  % changing font size
\def\scsize{12.5pt} % small-caps size

\def\smallcaps{smallc}

\def\face{\ifcase \fontface berkeley\fi}

\def\variant{\ifcase \fontvariant roman\or medium\or bold\or black\fi}

\def\style{\ifcase \fontstyle roman\or italic\or slant\or roman\fi}

\def\afont{\expandafter\csname\face-\style-\variant\endcsname} % actual font info

\def\setftsize#1{%
  \ifnum\fontstyle=3
    \font\afont=\fontname\csname\face-\style-\variant\endcsname\space at\scsize\afont%
  \else%
    \font\afont=\fontname\csname\face-\style-\variant\endcsname\space at#1\afont%  
    \xdef\ftsize{#1}\fi} 

\def\pwrite#1{{\setftsize\ftsize#1}}
%{\csname\face-\style-\variant\endcsname#1}}

\def\roman#1{\tmpVariant=\fontvariant\fontvariant=0\tmpStyle=\fontstyle\fontstyle=0 
\pwrite{#1}\fontvariant=\tmpVariant\fontstyle=\tmpStyle}

\def\rm#1{\tmpVariant=\fontvariant\fontvariant=0 \pwrite{#1}\fontvariant=\tmpVariant}
\def\mf#1{\tmpVariant=\fontvariant\fontvariant=1 \pwrite{#1}\fontvariant=\tmpVariant}
\def\bf#1{\tmpVariant=\fontvariant\fontvariant=2 \pwrite{#1}\fontvariant=\tmpVariant}
\def\bc#1{\tmpVariant=\fontvariant\fontvariant=3 \pwrite{#1}\fontvariant=\tmpVariant}

\def\it#1{\tmpStyle=\fontstyle\fontstyle=1 \pwrite{#1}\fontstyle=\tmpStyle}
\def\sl#1{\tmpStyle=\fontstyle\fontstyle=2 \pwrite{#1}\fontstyle=\tmpStyle}
\def\sc#1{\tmpStyle=\fontstyle\fontstyle=3 \pwrite{\expandafter\uppercase{#1}}\fontstyle=\tmpStyle}

\def\swfont#1{\def\arg{#1} \def\Berkeley{berkeley}
\ifx\arg\Berkeley\fontface=0\fi}

\def\\{\hfill\break}

\baselineskip=16.5pt \lineskip=2pt \lineskiplimit=2pt
\parskip7pt \parindent0pt

\parskip=10pt

\setftsize{15pt} (15pts)

hola chicos y chicas (roman)\\
\mf{hola chicos y chicas (medium)}\\
\bf{hola chicos y chicas (bold)} \\
\bc{hola chicos y chicas (black)}\\
\it{hola chicos y chicas (italic)}\\
\sl{hola chicos y chicas (slanted)}\\
\sc{hola chicos y chicas (small-caps)}\\

\setftsize{25pt} (25pts)

hola chicos y chicas (roman)\\
\mf{hola chicos y chicas (medium)}\\
\bf{hola chicos y chicas (bold)} \\
\bc{hola chicos y chicas (black)}\\
\it{hola chicos y chicas (italic)}\\
\sl{hola chicos y chicas (slanted)}\\
\sc{hola chicos y chicas (small-caps) needs a bit of work}\\


\setftsize{15pt} (back to 15pt and mixing styles and sizes)

\rm{roman line: \sl{slanted} \it{italic} \bf{ bold \sl{slanted} it{talic}} roman again}\\
\mf{medium line: \it{italic} \sl{slanted} \rm{roman \bf{roman bold}} \bf{black}}\\
\bf{bold line: \it{italic} \sl{slanted} \rm{roman still neds a bit of work}}\\
\rm{roman line: \sl{slanted} \setftsize{20pt} \it{italic} \setftsize{30pt}
 \bf{ bold \sl{slanted} it{talic}} \setftsize{5pt} roman again}\\
\mf{medium line: \setftsize{25pt} \it{italic} \setftsize{20pt}
\sl{slanted} \setftsize{15pt} \rm{roman \setftsize{10pt} \bf{roman
bold}} \setftsize{5pt} \bf{black}}\\
\setftsize{5pt} \bf{bold line: \setftsize{10pt} \it{italic}
\setftsize{15pt} \sl{slanted} \rm{roman still neds a bit of work}}\\

\end