Apollo Saturn V computer logic reverse engineered - with working model.

[Frantone]

For the full article about this with photos go to my Design and Engineering page:
http://www.frantone.com/designwritings/design_writings.html#LVDCcode

[dda]

Noob question. I havent seen transistors arranged in that way before, inputs on the emitters, and the collectors connected to the base of the third... What is actually happening here? Im having trouble following it.

[Frantone]

Noob question. I havent seen transistors arranged in that way before, inputs on the emitters, and the collectors connected to the base of the third... What is actually happening here? Im having trouble following it.

Ah - you have to think about the direction of current and the way transistors switch.  These DTL and TTL circuits work on the idea that you ground the emitter/cathode to allow current flow and otherwise the bases are pulled high.  Each gate assumes there is a high bit there unless it is told otherwise by a low (ground) state.  It seems bass-ackwards but this is how it was done.

[JackOfVA]

If my research is correct, the first TTL devices to hit the general market were by TI and it was 1962, a year or so after TTL was invented. If so, TTL was a known, but new, technology when the IBM 360 hit the market. Considering how long it must have taken for IBM to bring the 360 to market (Fred Brooks book, "The Mythical Man Month" featured his experience developing the initial 360 operating system as I recall) TTL was likely not available when the 360 was originally designed.

DTL was a few years earlier - I  recall seeing DTL surface mount flatpacks made by (I think) Westinghouse around 1966 when at University studying electrical engineering. At that time, all my home brewing of logic was with RTL, though, as it was considerably more available and affordable.

[Frantone]

If my research is correct, the first TTL devices to hit the general market were by TI and it was 1962, a year or so after TTL was invented.

I have read that as well, though I have found no real-world application of TTL that early.  I do think that the IBM LVDC was the first time a complete system was built on TTL.  I could be wrong, but I have found nothing this involved made from TTL that early.

[w2aew]

Another great video, Fran!  That chip mounting technology looks like the predecessor to C4 (Controlled Collapse Chip Connection), basically a micro-version of  BGA.

[Psi]

Any idea how many of those boards made up the entire CPU?

[Frantone]

Any idea how many of those boards made up the entire CPU?

I only have one board, but photos available online of semi-filled LVDC modules show many - and the system was triple redundant, with three computers working in parallel, and a majority vote system for final decision making of attitude and control.

[JackOfVA]

The Computer History museum says:

Patented by James Buie of Pacific Semiconductor in 1961, TTL (Transistor Transistor Logic) emerged as the most popular logic configuration of the next two decades. Unaware of Buie's work but inspired by an "all transistor" logic circuit described by Ruegg and Beeson of Fairchild, Thomas Longo led the design of the first TTL family, Sylvania Universal High-level Logic (SUHL) in 1963. Encouraged by SUHL's success in winning a high-profile Hughes military design (the Phoenix missile), TI introduced the competing SN5400 Series TTL family the following year. The company announced the SN7400 Series in low cost plastic packages for industrial customers in 1966 and quickly gained a greater than 50% share of the logic market.

http://www.computerhistory.org/semiconductor/timeline/1963-TTL.html

I recall SUHL after this jogged my memory.

[Raff]

Wow! without a doubt very cool! Thanks for the videos, i have subscribed to your channel.

[Frantone]

It works.....



I will make the video about how to Build Your Own LVDC Logic Devices with modern surface mount components next week.  Reflow your way into the Apollo Program!
 

[dda]

Noob question. I havent seen transistors arranged in that way before, inputs on the emitters, and the collectors connected to the base of the third... What is actually happening here? Im having trouble following it.

Ah - you have to think about the direction of current and the way transistors switch.  These DTL and TTL circuits work on the idea that you ground the emitter/cathode to allow current flow and otherwise the bases are pulled high.  Each gate assumes there is a high bit there unless it is told otherwise by a low (ground) state.  It seems bass-ackwards but this is how it was done.

Ah, cheers. I did some googlin', and thinking of that transistor as a couple of diodes makes it easier for me to visualise.

I also looked at the NOT gate on your website fran, my next question is about the two diodes next to the output of the not gate... What would be the effect of omitting them?

[HLA-27b]

Fran you've got me reading about LVDS and ECL ever since you posted the video. Thanks!

[Raff]

Well there goes Sunday 

[Frantone]

I also looked at the NOT gate on your website fran, my next question is about the two diodes next to the output of the not gate... What would be the effect of omitting them?

Hmmm...  Good question - Dual diodes is overkill and the lower NPN transistor is an adequate emitter follower in itself, so I would think it would be stable without the diodes.  I do think though that having at least the one diode between the upper emitter and the output would help a lot with balancing the output impedance when the NOT gate output goes high under load. 

[smashedProton]

Congratulations fran!  Not only for an excellent thread, but you have posted one of the few on topic threads     

[Frantone]

LVDC-NAND Dual PCB Prototype -

Demonstration of the production prototype of my LVDC NAND gate package, with dual surface mount PCBs.

[Frantone]

Final specs and artwork for the Do-It-Yourself LVDC project are here: http://www.frantone.com/designwritings/design_writings.html#LVDCbuild

Good luck, and have fun! O0

[seth13699]

Hi guys and gals,

First of all I've been lurking Dave's and Mike's (mikeselectricstuff) youtube channels (and this forum) for some time now and I'd like to take advantage of this opportunity to thank them both for sharing their accumulated knowledge over the years with all of us. Thanks guys!!!

I just found out about Fran's channel though and I was immediately hooked by the LVDC videos. That was awesome Fran!!! 

I am a fellow Apollo era hardware buff and I too acknowledge the importance of these relics and the tremendous impact they had in the industry over the years (albeit largely forgotten for various reasons as Fran pointed out).

Now to the point (after this brief intro). I own, among other things, 2 page assemblies. One from a LVDC "flight ready" spare, and another one from a cannibalized (literally!!!) test rig.

The first one is on display in my collection and it's in pristine condition (like new!!!). Here are a few pics:









The other one though had a tough life 

I was told it spent years on a junkyard exposed to the elements, and that left it's marks as you can see below:





I was planning to "destructively" reverse-engineer that one, popping the lids off some of the flat packs or just see if the transistors still work after all this years. Unfortunately I simply don't have the time (or access to fancy X-Ray machines  ).

I'm willing to donate that PCB to either Dave, Mike or Fran in exchange of a video (or a series of videos) dedicated to this extraordinary piece of Space Age history.

Any volunteers? 

P.S.: I'd prefer an in depth analysis (even if that meant de-soldering or "breaking" components) but you can choose to preserve it as is (or restore it to some extent) instead. The choice is in the hands of the chosen one!!!

For SCIENCE!!!

[bradleytron]

Hi guys and gals,

First of all I've been lurking Dave's and Mike's (mikeselectricstuff) youtube channels (and this forum) for some time now and I'd like to take advantage of this opportunity to thank them both for sharing their accumulated knowledge over the years with all of us. Thanks guys!!!

I just found out about Fran's channel though and I was immediately hooked by the LVDC videos. That was awesome Fran!!! 

I am a fellow Apollo era hardware buff and I too acknowledge the importance of these relics and the tremendous impact they had in the industry over the years (albeit largely forgotten for various reasons as Fran pointed out).

Now to the point (after this brief intro). I own, among other things, 2 page assemblies. One from a LVDC "flight ready" spare, and another one from a cannibalized (literally!!!) test rig.

The first one is on display in my collection and it's in pristine condition (like new!!!). Here are a few pics:









The other one though had a tough life 

I was told it spent years on a junkyard exposed to the elements, and that left it's marks as you can see below:





I was planning to "destructively" reverse-engineer that one, popping the lids off some of the flat packs or just see if the transistors still work after all this years. Unfortunately I simply don't have the time (or access to fancy X-Ray machines  ).

I'm willing to donate that PCB to either Dave, Mike or Fran in exchange of a video (or a series of videos) dedicated to this extraordinary piece of Space Age history.

Any volunteers? 

P.S.: I'd prefer an in depth analysis (even if that meant de-soldering or "breaking" components) but you can choose to preserve it as is (or restore it to some extent) instead. The choice is in the hands of the chosen one!!!

For SCIENCE!!!

How about your friendly local dentist, might they allow you to use their x-ray machine?

[seth13699]

I tried...no joy 

I guess she (my dentist) wasn't convinced about the value of the artifact and the importance of X-Raying it.

Bummer...

[Frantone]

Hi guys and gals,

I just found out about Fran's channel though and I was immediately hooked by the LVDC videos. That was awesome Fran!!! 

I'm willing to donate that PCB to either Dave, Mike or Fran in exchange of a video (or a series of videos) dedicated to this extraordinary piece of Space Age history.

Any volunteers? 

For SCIENCE!!!

YYYYEEEEESSSS!!!!!!    I WILL TAKE IT! 

Email me through my website www.frantone.com and I will arrange shipping.  The exposed junkyard board would be ideal for surgery - I would like to take off some of the devices to check the values and such for the gates.

Awesome!
    O0         

[seth13699]

YYYYEEEEESSSS!!!!!!    I WILL TAKE IT! 

Email me through my website www.frantone.com and I will arrange shipping.  The exposed junkyard board would be ideal for surgery - I would like to take off some of the devices to check the values and such for the gates.

Awesome!
    O0      

You have PM...

 

[BartManInNZ]

This thread along with your site Frantone has given me much joy - the amount of awesome is too much!
Keep up the great work!

[mwtheobald]

Wicked reverse engineering!  And yet another set of video's to watch