newbie to 16v8

A GAL16V8, which I guess is what you mean, has only...

- 8 bits of storage

- 18 user I/O pins, of which one must be taken as a clock in most cases so your multiplier surely cannot be very big! You could make a multiplier with two 4-bit inputs and an 8-bit result... probably. If you have *lots* of 16V8s on a board, you could make a bigger multiplier.

When I did a Google search for GAL16V8, the first hit I found was the Lattice data sheet. (I used to know those devices inside-out, but I haven't used one for so long that I thought I'd better remind myself of the details.) Not a bad place to start.

Hello Jonathan,

Thanks for your response. you are right, I did download it but one thing that I need to know how can I find a right flow? and associate it with a multiplier 4 by 4? it seems there are other controlling inputs such as Vcc (or maybe I'm wrong) but is there any example of an adder for instance?

Once again thanks. amit

Amit, you will not fnd a multiplier, nor even an adder. The chip has lots of wide AND gates that can be ORed together, and that's the (very low) level of abstraction you should use to design. Back to basics (or is it forward to basics for you ?). Good exercise in logic design, and in logical thinking. Greetings to your teacher or prof. Peter Alfke

That should be easy. Which logical function has your tutor asked for ? What examples has he given ?

How many bits wide ? - did the tutor say ? One obvious ceiling is you only have 8 outputs, but there are other lower ones. One simple Multipler expression is a ROM, and a 2b x 2b multipler, can fit in a 16x4 ROM - and that will likely fit into a 16V8. The 22V10 will fit a larger multiplier.

-jg

Your best starting point would be to ask your tutor why he thinks you need to work with a technology that nobody has used for at least ten years. You might be able to catch him after his lecture on valves (vacuum tubes) and germanium transistors.

Quite a few introductory courses are taught using a SPLD/CPLD

- after all, AND/OR/XOR Logic and D-FF have not changed :)

The student learns using Boolean equation entry, which teaches them how the logic actually maps, and is also a common language in report files.

The devices come in DIP packages, and can also be easily vector tested on device programmers, which brings the silicon inside the design loop.

The 16V8 may not be seen much in new designs, but it is still active in production [ We still buy ATF16V8BQL for production :) ] and the modern 32 macrocell CPLD's are a pretty easy step from the 16V8. Some courses could include both -depends on the hours allocated.

-jg

Are you sure modern fpga's work differently? The latest processors still use the same base technology invented decades ago. I've learned how processors / small computers work from books describing the 8080 while the 486 was readily available. The theory behind it however still holds true for today (and probably many tomorows). In fact, old technology is usually much simpler and easier to understand and the documentation contains a lot more background information which is held for granted nowadays. For instance try to find a datasheet from an EPROM which lists the wavelength it needs to get erased... I had to dig up a datasheet from 1982.

That goes for many things. On an old car you could adjust the breaker points and the carburator, on an old radio you could change the tubes, and on even a new bike you can still change the chain and the bowden wires, Good as a tutorial, but how much time do you want to spend there? Who needs to know the EPROM erasure wavelength of light when everybody is using Flash, and no light? On th other hand... I get annoyed when designers blindly think that chips can add, multiply, and perform a Fourier Transform, without any understanding or appreciation of the underlying physics. We need some balance... Peter Alfke

That was the point I was trying to make. Whilst understanding the concept of implementing arbitrary logic functions using a sum of products architecture, I can see little point in making someone develop a design to go in an obsolescent part. Although most modern CPLDs still use sum-of-products architecture, it is very unlikely that you would ever need to code a design directly into such an architecture in this day and age. It would be akin to getting someone to program a processor directly in machine code, ignoring the perfectly good (and probably free) assembler that is available.

Yes, knowing what you can't do, is important. I suspect the tutor threw in the Multiplier question for exactly that reason : To impress on the students what cannot fit into a device :) You can fit a Multiplier into a 16V8, the question is up to what size!

-jg

You've lost me a little here ?

You write for SPLD in HDL - Boolean Equation Entry languages like CUPL, ABEL, or others.

You can also write in Table form, or State engine form, all of which port quite easily to higher end HDLs

It is all Text Editor / named variables / and comments in source code stuff.

You never work at the JED fuse-file level ?

-jg

I did fifteen years ago, but not these days.

With only 8 registers and product terms, you'd have to make it a bit serial multiplier, and even then the parallel multiplicand is going to limited in size. See the multipliers page on my website for details.

The 16V8 is a 30 year old part, it's very tiny. Your question is like asking how to build a house out of one brick, you can't do it. However you can build a house out of a lot of bricks and in the same way you can build a multiplier out of a lot of 16V8s. You can implement 4 carry save adders in a 16v8 which you can use to build a Wallace tree. You can also implement a 6 bit look ahead adder with a V8 which you can use to sum up the carry save terms at the end of the pipe.

Hi Ray,

Thank your response. what is your webiste's domain?

Thanks, ak

I think I'd try

- Brian

I firmly believe that there needs to be some sort of universally-accepted occupational guidance test put into place. Here is a candidate for the first and only question:

If one fails this test then that person would be forced to look deeply into a mirror and would be strongly encouraged to consider a more menial occupation.

Bob

Ok bob.