6502.org

It puts you in a time, and also in a tribe...

Since I am hosting a nasty flu, some quiet time in front of the wood-stove with 25 SRAMs has been very relaxing.
I actually made some progress, but the task does seem monumental!

First, the middle pins are bent outwards (this is VCC and GND on both sides)...



Then, I add the decoupling caps on each side and bend them towards the IC...



I then add solder to each of the socket pins and onto the IC pins.
So far, I have all 25 SRAMs on their sockets...



Now the task of cutting 900 tiny wires to connect all the pins to the DIP sockets!

Brad

Wow, that's dedication. If it was me I'd be designing an adapter pcb... cutting and stripping that many wires would not be my most favorite task... I recently designed and made a little 40-pin breakout pcb. They ended up costing about $1 each for a run of 30, which for me would be worth it just to avoid the hassle
http://www.6502.org/users/sjgray/projec ... index.html

Anyway, keep up the great job! I find it fascinating.

Steve

I'm still amazed the pins don't break off. I'd be fearful of trying that on a five dollar SRAM.

Thanks! The Visual memory Display is a cool project.

I have never broken an SRAM yet. Well, at least not physically.
I reversed VCC on one breadboard row, and toasted 2 of them a while back.

There is something fun about doing things the hard way.
I am cutting the wires now, and have it down to assembly line speed!

Brad

Or you could use three of my 4Mx8 5V 10ns SRAM modules (each one using eight Cypress CY7C1049D-10VXI 512Kx8 5V SRAMs, four
on each side), now available with .300" row spacing.

Are you referring to the SRAM packages?

No, the module itself. I was reluctant to do it, but due to demand, it's now available (for $10 extra, since it's more work for me). The picture shows the module pins with .300" row spacing. The SRAM ICs are still SOJ.

Those modules would certainly make my job easier!
But since Vulcan-74 is my "Hot Rod", I must hand craft it 100% myself.

Now that the Cypress parts are out of production, you can use this one...

http://www.digikey.com/product-detail/e ... ND/1831407

These are the ones I am soldering down right now.
Actually just finished the first one, and it has passed the video test.

Now that I have all the wires cut, it looks like I can complete one SRAM every half hour or so.
If my flu hangs on, I may just go at it all day tomorrow. Only 12 more man-hours of soldering!

Brad

Thanks. I see Cypress is still making the 1049, but the D after it is replaced with GN. It's apparently only a die change. With a quick look, I didn't see any differences that would concern the user. They certainly didn't make any of the improvements I would have liked. I still have quite a lot of the D version left though, which I got at probably less than half what the hobbyist has to pay, because of the quantity I got.

Isn't the Cypress GN only available as a TSOP package now?
I almost went that way, and considered making TSOP to DIP adapter PCBs, but it seemed like the easy way out!

3 Working SRAMs mounted now. It's very relaxing work, and a great way to spend a flu weekend.

Brad

No, see the lower half of p.14 of the data sheet at http://www.cypress.com/file/221601/download (.pdf). SOJ-36.

The Cypress search results summary page showing the three types of 1049 is at http://www.cypress.com/search/all/CY7C1 ... 3Aproducts .

I wonder what the market for SOJ packages would still be these days?
Last time I seen SOJ sockets was on ISA video cards and 386/486 mainboards as cache RAM.

• 4.5 V to 5.5 V VCC = Min, IOH = –0.1mA VCC – 0.5

I noticed that in the GN data sheet.

True, and that's good; unfortunately with any load (like while charging bus capacitance), you get Vcc = Min, IOH = –4.0 mA, IOH(min)=2.4V which will have the effect of slower response by devices that need it pulled up higher. It will take more time to finish bringing the line to a valid CMOS logic-high, since the pull-up current falls way off after the half-way point in the transition. (It won't be a problem the the '816 where you use a 74ACT245 bus transceiver or equivalent anyway though.)