Jump to content

Built a Processor?


nullArray
 Share

Recommended Posts

Has anyone built a processor before?

I'm building one now..., I have the registers done and a 32 bit ALU..., it's a pretty complicated, tedious process. It's amazing learning about how all these things work. It really is just a bunch of gates. Some of the concepts are really intangible until you see it happening.

For example (dumbed down ((as I understand it, I hope I'm right))), to add, you choose the operation (for mine I think the code is 0001), then the numbers go in and the operation is executed bit by bit and carried out to the next ALU 32 times until the result is outputted. I never would have gotten how it worked prior to doing this.

Anywho, here's my ALU wiring diagram.

post-12442-1238169606_thumb.jpg

If you've got time, it's worth attempting in Quartus or something.

EDIT: No megafunctions except multiplexors!, that would be cheating!

Link to comment
Share on other sites

Has anyone built a processor before?

I haven't built one, but I am interested in the design of processors (and other ICs). I have decapsulated many chips to study under microscope (but I have never fully reverse-engineered a chip, usually I am just interested in some design aspects and memory contents). Here's a flickr link of an older ROM chip (from a NES Super Mario Bros/Duck Hunt cartridge) I photographed.

Are you going to implement the design on an FPGA, or is it simulation only?

Link to comment
Share on other sites

What software are you designing it in? I've done some really simple digital component design in Logisim which isn't really professional by any means but does the job for learning your way around things like that. Or are you using something like verilog?

Link to comment
Share on other sites

What software are you designing it in? I've done some really simple digital component design in Logisim which isn't really professional by any means but does the job for learning your way around things like that. Or are you using something like verilog?

Using Quartus for design this time, going to put it on a Altera board. I've built it using only logic gates, wires, and multiplexors before though, albeit it was only four bits, not 32.

Link to comment
Share on other sites

I haven't built one, but I am interested in the design of processors (and other ICs). I have decapsulated many chips to study under microscope (but I have never fully reverse-engineered a chip, usually I am just interested in some design aspects and memory contents). Here's a flickr link of an older ROM chip (from a NES Super Mario Bros/Duck Hunt cartridge) I photographed.

Are you going to implement the design on an FPGA, or is it simulation only?

So you use chemicals and an ultrasonic vibrator to disassemble the chips? can explain ho you remove the silicon casing?

Link to comment
Share on other sites

So you use chemicals and an ultrasonic vibrator to disassemble the chips? can explain ho you remove the silicon casing?

I use nitric acid to remove the plastic packaging around the chip, which leaves a nice clean silicon die (still working). I use the ultrasonic bath for cleaning the chip.

The chip is a silicon base with metal and insulating layers deposited on top, with a glass-like protective layer on top of all that. As long as no chemicals are used which damage the exposed surfaces, the chip continues working. Or sometimes I use other chemicals to etch away some of the metal and insulating layers, to be able to study the lower layers of interconnects or the silicon base itself. (of course once part of the chip is removed, it will no longer work)

This picture shows a chip (the same as the link in my previous post) with the bonding wires that connected the die to the pins on the plastic package. The plastic package has been removed (dissolved in nitric acid), but the wires are still attached to the die.

Link to comment
Share on other sites

how hard is it to get nitric acid and how expensive?

I have an account with a lab chemical supplier, I pay about a hundred bucks for 250 mL. Most commonly available nitric acid is 69%, which will cause damage to chips - for work with ICs 90% or higher is used (or even >99%).

Nitric acid is pretty aggressive stuff, it can burn your skin and the fumes cause lung problems. Some things, when mixed with nitric acid, ignite. Nitric acid can be used in explosives, in some areas purchasing high purity nitric acid may get you put on some kind of watch list, at the least.

Link to comment
Share on other sites

Scary stuff.

Link to comment
Share on other sites

I have two, seven-segmented displays I'll be hooking it up to to perform see outputs of the calculations.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...