This page describes the IBM SMS card "DFA", and is part of the SMS card database.

Function of the card:
Mup number 12
SDTRL mup number 12
SDTRL MUP Number 12

Dual Buffered RS Flip-Flop

Saturated Drift Transistor Resistor Logic (SDTRL) is a form of resistor-transistor logic using faster drift-field transistors.

A Multiple-Use Package (MUP) card has circuits jumpered together directly on the card to form more complex circuits.

Part number: 370224

PCB number: 484039 , hole pattern: 399446

Used in: IBM 1620, IBM 1410, IBM 1414 I/O Synchronizer, 1622


L: Limiter or Clamp. Limits or clamps a voltage or current to a predetermined value.


A *S2
B Q1
C *Q1
D *Q2
E Q2
G *S2
H *R2
K *S1
L *S1
M -12V
N +12VM
Q *R1
R *R1
References: IBM 1620 Instructional System Diagrams, p482
Coslet data
1410_SMS_VOL_1.pdf, p41
IBM 1620 FE Catalog

This page created by Ken Shirriff on Wed Sep 15 18:15:10 2021.

The information on these pages comes from a variety of sources, especially old IBM documents on, as well as information from the IBM 1401 restoration team, especially Tim Coslet's SMS data and Jim Hunt's data. Much of this information was obtained through OCR, so don't expect complete accuracy. These pages are not associated with IBM in any way.