@Blair Vidakovichrecently added a great page to the #Hackaday TTLers:The Electronics of IBM Standard Modular System Logic
He reviews the individual ECL gates of SMS modules and they are pretty simple :
![](https://bootlicker.party/IBM_SMS_images/006_SMS_ECL_Pos_AND_Neg_OR.png)
![](https://bootlicker.party/IBM_SMS_images/007_SMS_ECL_Neg_AND_Pos_OR.png)
Compare this to the "early ECL" diagram I mentioned earlier and see how they match :
![](https://cdn.hackaday.io/images/3905271483084902922.png)
Unfortunately, the IBM way has 4 power rails (with 6V differences). That's a LOT, and a significant waste, but at that time, transistors were very expensive...
Discussions
Become a Hackaday.io Member
Create an account to leave a comment. Already have an account? Log In.