IC that can store data?

[Alex101]

Is there like a easy to use IC that can store data? Something that could replace a SR Latch circuit?

Data can be permanent or temporary.

I don't feel like using NANDS to store data... Need too many of them.

Any thoughts?

It would be nice if it was relatively small and could store at least 4 bits of data.

It must be very easy to read/write data from the IC. I don't want to have to have too many other components to get it to work.

 

[Mikebits]

Uh, what about RAM? Most CPU's have internal RAM.

 

[Alex101]

RAM is too expensive, too complicated, and I don't need *that* much memory.

If I could have a little IC that can store at least 4 bits of data that would be good. A little more would be even better.

I'd like it very much if I could also see a logic gate diagram of the chip.

 

[MrAl]

Hi,

Did you check out the 74LS74 or the cmos version?
That's 4 bits.

 

[Mikebits]

Hi,

Did you check out the 74LS74 or the cmos version?
That's 4 bits.

Isn't the 7474 a Dual FF. Two bits? I don't think you can count the /Q pins.

 

[Mikebits]

RAM is too expensive, too complicated, and I don't need *that* much memory.

If I could have a little IC that can store at least 4 bits of data that would be good. A little more would be even better.

I'd like it very much if I could also see a logic gate diagram of the chip.

You can get RAM chips for like a buck. For 4 bits take MrAl suggestion and use some flipflops.

 

[Alex101]

Will this work?: 74HC374N - Octal D-Type Flip-Flop 3-State

What does 3 state mean? Can someone explain how I use this? How can a flipflop store data? I thought they were used as timers...

god this is confusing

 

[Mikebits]

Oh boy, and no offense but I really think your aspirations to build a CPU are a bit more than you can chew. I base this on the questions you are asking.

3 state means the device can drive an output high, low, or go high impedance which means it becomes invisible to the rest of the circuit; in other words, it no longer drives a circuit. This is important on bidirectional lines.

Flipflops can store data because you can put a logic 1 or 0 on one data line, clock it with a strobe and the bit will maintain its state until another strobe, commonly called a write strobe. Later on you can read the stored bit on the flipflop. Reading the bit on the flipflop can be done in several ways. One is to have it connected to a 3 state device which can be turned visible again by a direction strobe and then a read strobe.
With the advent of Large scale integration, most of this logic goo has been incorperated into a single chip, and the designer need only worry about read/write strobe and maybe a few other signals. Without having a chalkboard and you in front of me, this is hard to explain.

 

[Alex101]

What kind of IC could I use to store more than just 8 bits? For example, what if I want to store 1MB - 10MB of data?

Are there any easy solutions? If a 4bit flipflop has 8 pins, then a 1MB flipflop must have millions...

What can I do? Sorry for my stupidness

 

[Nigel Goodwin]

You use RAM chips, as everything else does - you have address lines and data lines, so you don't need that many pins.

 

[Alex101]

I can't find any RAM IC's on ebay. All I got is the ram chips you stick inside your computer.

 

[Nigel Goodwin]

I can't find any RAM IC's on ebay. All I got is the ram chips you stick inside your computer.

Look for 6116, an old CMOS 2K static RAM chip in a DIP package.

You're not going to find any large devices that are simple to use - and static RAM isn't cheap.

But I agree with everyone else, it's a pretty pointless exercise trying to build a CPU.

 

[Alex101]

Well how hard is it to build a computer that can run custom games and programs out of these NAND and RAM chips?

 

[Nigel Goodwin]

Well how hard is it to build a computer that can run custom games and programs out of these NAND and RAM chips?

How many years, and how many thousands of dollars, have you got available?.

A simple PIC, that costs almost nothing, is going to far out perform anything you're going to make in any reasonable time, and for any reasonable amount of money.

 

[3v0]

Well how hard is it to build a computer that can run custom games and programs out of these NAND and RAM chips?

Computers, particularly microcontrollers are in everything and everywhere. That does not mean they are simple.

Everyone has to learn the basics first. Can you breadboard a uC with a LED and program it to blink without copying code from somewhere?

 

[blueroomelectronics]

Well how hard is it to build a computer that can run custom games and programs out of these NAND and RAM chips?

Hard. Just look at how many transistors are in a typical microcontroller.
Sounds like the OP has never programmed a micro before in assembler.

 

[MrAl]

Isn't the 7474 a Dual FF. Two bits? I don't think you can count the /Q pins.

Yes, that was a typo.
I meant to type 74LS75 instead, which is a 4 bit latch.

My apologies.

 

[Alex101]

Hmm... well thanks for your reply guys. I'll probably have to have a long think about it.

Hard. Just look at how many transistors are in a typical microcontroller.

Yes, but you're talking about very very fast computers, that have all kinds of specialized circuitry. It wouldn't be anywhere near that hard to make a computer if it only had, say, 2 bytes of memory.

Take a look at this wikipedia 'home-made' computer made from 7400s:

An Implementation of a 4-bit two register computer, including six cpu assembly instructions: READ (read input), INCB (increment register B), MOVAB (move contents of register A to B), MOVBA (move contents of register B to A), RETI (return from interrupt), JMP (jump).

**broken link removed**

 

[Salgat]

With the development costs of FPGAs being so low, would others here consider it impractical to develop basic CPUs using discrete chips?

 

[dknguyen]

With the development costs of FPGAs being so low, would others here consider it impractical to develop basic CPUs using discrete chips?

Definately, use an FPGA. You learn just as much if not more.