DIY RAM for Your Micro

As you might know, my DIY RAM instrucables were quite popular a few months ago, well for a week.  I showed you how to make a TTL RAM and a CMOS RAM.  This time I am going to show you how to make a full byte of ram for your microcontroller**!!!  It will use the CMOS version and be a D Latch based design, sorry for you TTL fans. That's next thought!!!  We will be using the 74hc(t)00 Quad NAND gates.

**Restrictions apply.  See back for details.  Not valid in all States and Territories.  Valid in some parts of Canada and most of Europe.  No purchase necessary.  

Step 1 The Stuff You Need to Have or Get

The Stuff You Need to Have or Get is what we will need for the RAM. (you think: Gee really?)

Its a much shorter list this time:

8 74hc00 or 74hct00 Quad NAND Gates. For the circuits used in this instructable, only these chips will work.
8 4.7k -10k resistors
8 small signal diodes - the common 1n4148 variety works well
A breadboard with at least 63 rows, or you will need more than 1.
Wire - it helps to connect things (you think: Is he for real here?)
Wire Cutters - (you already think: Let Me Guess...) Yup, they make cuttin' wire so nice!
Needle Nose Pliers - optional, but i find them nice for bending and placing wire.

Optional:
8 LEDs
8 Resistors (that work with the LEDs)

Comments

[yaly]

Hi I have 4 DRAM ICs each 256kb so 1Mb in total IC part number:MT4C4256-8 can i use them it with arduino?

[yaly]

does the readRam{}; command work with arduino uno r2 or r3 ? Please some body answer me

[dohunagamez]

NAND gates? so that would effectively make it an SSD?

[soshimo]

No, SSD's are not the same. Flash memory is very different than RAM. Flash memory retains it's contents after power has been removed whereas RAM requires power and, when dynamic, constant refreshes. Flash memory is based on EEPROM technology and is fairly new (developed in the 80s I believe).

[takide]

cant you replace the NAND gate chips with transistors?

[Teslaling]

Yes you could, i wrote an instructable on that a while ago, just search "cmos ram"

[Barnaby Walters]

Could you dramatically improve size/storage ratio by using integrated D-Latch chips?

Nice instructable!

[Teslaling]

I could, but that's boring!!!

[icsnerdics]

next step use a set of nmos trans, via nmos logic inverters with depletion nmos load.
that's quite fun.

[Barnaby Walters]

Fair enough ;) I think it's great that you've done it the way you did, so that people have a better idea of what's going on inside RAM. After all the symbol for a D-Latch is just an ambiguous box, whereas you can actually see what an inverter does.

[mischka]

Well thats great. I always need an extra byte for my arduino ;-). No, really: cool instructable!

[Teslaling]

Haha, thanks!

[rtty21]

Thanks for posting this! I hope your inst'able gets featured!

I plan to try this out within a day or two. I'll post a message and a few pics when I do!

Great project!
regards,
rtty

[Teslaling]

Thanks man! It just got featured!

Good luck to you, can't wait to see your's!!!