Author Topic: How to: Design a microprocessor (Read 45925 times)

TsukasaZX · « **Reply #45 on:** May 03, 2011, 04:01:44 am »

Quote from: Qwerty.55 on May 03, 2011, 04:00:21 am

Er, I didn't use any of these

You're a maniac . _ .

AngelFish · « **Reply #46 on:** May 03, 2011, 04:02:00 am »

What's wrong with that?

TsukasaZX · « **Reply #47 on:** May 03, 2011, 04:03:07 am »

Designing any sort of sequential logic circuit without use of state diagrams and the like? Madness! Utter madness! ... You'd make a great engineer because you are obviously the world's biggest masochist and/or the world's smartest engineer

AngelFish · « **Reply #48 on:** May 03, 2011, 04:04:25 am »

lol, logical circuits just make sense to me.

yrinfish · « **Reply #49 on:** May 12, 2011, 01:21:30 pm »

Er, are you guys going to hate me if I ask a question that is most likely connected to a project that is too big for me?

How the **** do I design an 4 bit instruction set?

This is my latest one:

nop jz jnz jmp push pop call ret not lit ld sto add xor or and

lit is a inmediate value to a register.
ld and sto are for RAM

Do you have any examples? Do I miss something?

matthias1992 · « **Reply #50 on:** May 12, 2011, 02:23:45 pm »

Please, If you feel comfortable with logisim, use it but Multimedia Logic is SOOOOOOO much easier, really easy to use, pretty fast, has snap to grid functions can read and write files and has memory modules! its really great give it a try, not very well documented or well known in general but its so easy...

So at least take a look at I say...its really worth it!

http://www.softronix.com/logic.html

site may look like *** but its really great software, been using it more than 2 years now!

matthias1992 · « **Reply #51 on:** May 12, 2011, 02:42:36 pm »

Quote from: yrinfish on May 12, 2011, 01:21:30 pm

Er, are you guys going to hate me if I ask a question that is most likely connected to a project that is too big for me?

How the **** do I design an 4 bit instruction set?

This is my latest one:

nop jz jnz jmp push pop call ret not lit ld sto add xor or and

lit is a inmediate value to a register.
ld and sto are for RAM

Do you have any examples? Do I miss something?

sorry for the double post how about adding a neg (2's complement) lea (load effective adress) might also be nice but isn't a necessity for a 4 bit microprocessor at all. Hardware multiplication is always nice but not necessary either. Also I recommend you consider properly what does it need to do? this should be the most fun part, you are making your own language, make sure you comprehend it yourself. make it as you wish it.

yrinfish · « **Reply #52 on:** May 12, 2011, 03:00:08 pm »

Er, do you really think that that is better?
Logisim has a cleaner design, is portable, and I do really prefer the symbols over those MMLogic has.
I do not see things that I miss in Logisim... (OK, that file stuff may be useful but I do not miss it)
MMLogic was last updated 7 years ago...

But please back to my question

yrinfish · « **Reply #53 on:** May 12, 2011, 03:02:40 pm »

er, not add 1 is the same as neg? and I do not really have much space left (er, ok, no space left)

How many registers should I use?

remember, this is more than slightly linked to creating the whole thing using logic gates.

AngelFish · « **Reply #54 on:** May 12, 2011, 03:56:57 pm »

Quote from: yrinfish on May 12, 2011, 01:21:30 pm

Er, are you guys going to hate me if I ask a question that is most likely connected to a project that is too big for me?

How the **** do I design an 4 bit instruction set?

This is my latest one:

nop jz jnz jmp push pop call ret not lit ld sto add xor or and

lit is a inmediate value to a register.
ld and sto are for RAM

Do you have any examples? Do I miss something?

Basically, the only way to do it is to design the whole computer. There are actually quite a few ways to do it, though. I'll assume you use what's called the Princeton architecture rather than the Havard architecture (Google those if you're unfamiliar). The simplest way within the Havard architecture is to use "microcode" to tell the program to react to the opcode. To access the opcode, you need to retrieve it from memory using a data bus. Then, with microcode, you need to use the opcode to retrieve the microcode from a ROM array. This is easily done by using the Opcode as the selection inputs to a multiplexer. The Microcode should then be written so that it controls the individual components to direct your data (from memory or elsewhere) into the proper components and places. That's one of many ways to implement an instruction set.

Also, I highly recommend not using a stack. That's a bit more advanced than you probably want to go. Keep in mind that the features included in most modern processors are not always easy to replicate in hardware. As TsukasaZX said, you should use Verilog and an FPGA if you want a fully featured microprocessor.

yrinfish · « **Reply #55 on:** May 13, 2011, 03:58:52 am »

No stack? er, ok 4 more opcode spaces... how do I call functions then?

and is princeton the same as von Neumann, because that is the one I want, I LOOOOOVEEE SMC.

I will have a look at a hexadecimal z80 chart for ideas.

AngelFish · « **Reply #56 on:** May 13, 2011, 05:05:01 am »

Quote from: yrinfish on May 13, 2011, 03:58:52 am

No stack? er, ok 4 more opcode spaces... how do I call functions then?

and is princeton the same as von Neumann, because that is the one I want, I LOOOOOVEEE SMC.

Er, not sure why I used Princeton instead of Von Neumann, but yeah. Also, why do you need to call functions? A 4 bit PC can only address 16 words of memory unless you use more advanced techniques like paging or virtual memory. There isn't much room for the main program, let alone subroutines.

yrinfish · « **Reply #57 on:** May 13, 2011, 05:23:34 am »

Thats true, what opcodes should I add in the new space?
maybe sub, neg, shift...
How many registers should I use? 4 is useful, but when I make the ip non-accesible with assembly, 2 could be enough.

Broseph Radson · « **Reply #58 on:** May 16, 2011, 08:07:38 pm »

After its done, you should make a tutorial on how to do this with Minecraft redstone circuits

AngelFish · « **Reply #59 on:** May 18, 2011, 03:41:18 pm »

lol, it's basically the same thing, except you have to build the logic gates yourself

Author Topic: How to: Design a microprocessor (Read 45925 times)

TsukasaZX

Re: How to: Design a microprocessor

AngelFish

Re: How to: Design a microprocessor

TsukasaZX

Re: How to: Design a microprocessor

AngelFish

Re: How to: Design a microprocessor

yrinfish

Re: How to: Design a microprocessor

matthias1992

Re: How to: Design a microprocessor

matthias1992

Re: How to: Design a microprocessor

yrinfish

Re: How to: Design a microprocessor

yrinfish

Re: How to: Design a microprocessor

AngelFish

Re: How to: Design a microprocessor

yrinfish

Re: How to: Design a microprocessor

AngelFish

Re: How to: Design a microprocessor

yrinfish

Re: How to: Design a microprocessor

Broseph Radson

Re: How to: Design a microprocessor

AngelFish

Re: How to: Design a microprocessor