VHDL, Truth tables and Digital circuits, what to begin with?

[BlackOps]

vhdl truth table

i am reading now a book of Enoch Hwang. about digital design. i covered combinational elements already. and as i see from the book, in the beginning he describes every circuit with truth table,karnaugh maps, logical expressions,then he gives the circuit... at last he gives VHDL code, which looks so easy.. and after looking at this VHDL code, i think do i even have to mess with digital circuits,logical expressions,and karnaugh maps?

for karnaugh maps i am sure no...
but now i want to see how YOU, the experienced ppl do begin to write your VHDL code, i mean from what exactly you begin?

for example, lets say i must design 8-bit ALU, which does logical and arithmetic operations from scratch using VHDL. so what to begin first with?

and the second question is, as i saw there are three types of VHDL coding: structural, dataflow, and behavior... which one is better to be used? what do You use?

thanks

 

[brmadhukar]

vhdl programs of digital circuits

(1) Get a simulator and start. Probably get some code on the net and walk thru
(2) What you need to use depends on you preferences. If you are good at the HW design go ahead and use data flow and for complicated systems use behavioral.

BRM

 

[anoop12]

vhdl truth table

VHDL is just a programming and modling language. Before programming ,
you must know what to program, how to program and why to program. Basic concepts of digital circuits and timing concepts are important as well.