TABLES.DAT is probably of no use to you.  It contains mostly lookup tables
for mathematical functions such as SIN.  Remember that back in the dark ages,
floating point code used to be really slow!  Since you asked, here's some C
pseudo-code which explains how I created the TABLES.DAT file:
----------------------------------------------
short sintable[2048], radarang[640];
char textfont[128][8], smalltextfont[128][8], britable[16][64];

for(i=0;i<2048;i++)
	sintable[i] = (short)(16384*sin((double)i*3.14159265358979/1024));

for(i=0;i<640;i++)
	radarang[i] = (short)(atan(((double)i-639.5)/160)*64*1024/3.14159265358979);

The 8x8 text font is extracted from the BIOS of the VGA card
The 3x5 text font was designed by me (Ken Silverman)
 
for(i=0;i<16;i++)
{
	a = (double)8 / ((double)i+8);
	b = (double)63 / pow((double)63,a);
	for(j=0;j<64;j++)
		britable[i][j] = (char)(pow((double)j,a)*b);
}
 
TABLES.DAT file order:
	write(fil,sintable,2048*2);      /*sin (and cos) lookup table*/
	write(fil,radarang,640*2);       /*atn lookup table*/
	write(fil,textfont,128*8);       /*8x8 text font for ASCII chars 0-127*/
	write(fil,smalltextfont,128*8);  /*4x6 text font for ASCII chars 0-127*/
	write(fil,britable,1024);        /*gamma correction lookup table*/