IBM System/370 145 Manual page 21

Solid Logic Technology (SLT)
Monolithic technology is a bre!akaway from the hybrid circuit deqign
concept of SLT and can best be e~plained by comparison with SLT. As
shown in Figure 10.05.1, SLT circ:uits were implemented on half-inch
ceramic squares called substrates. Metallic lands on the substrate
formed interconnections onto which the components were soldered. These
components consisted of transistolrs and diodes, which were integrated on
silicon chips about the size of a. pinhead, and thin film resistors. An
SLT chip usually contained one component, and several chips and
resistors were needed to form a circuit. In general, an SLT substrate
contained a single circuit.
one component
Figure 10.05.1. SLT substrate
Monolithic System Technology (MSTl
Ceramic substrate
with interconnections
Monolithic system technology also makes use of a half-inch-square
ceramic substrate with metal interconnections onto which chips are
placed. However, in monolithic logic circuitry, large numbers of
elementary components, such as transistors and resistors, are integrated
on a single chip. In the Model 145, an MST logic chip is slightly over
a sixteenth of an inch square and contains over 100 components, which
can form up to eight interconnected circuits. This compares to a single
component on an SLT chip. MST logic modules, each consisting of one
substrate, are mounted on circuit cards, which are in turn mounted on
circuit boards (as in SLT logic).
MST logic offers the following advantages over SLT:
• MST logic circuitry is intrinsically more reliable because many
circuit connections are made on the chip, significantly reducing the
number of external connections.
• Faster circuit speeds can be obtained because the path between
circuits is considerably shorter. For example, the MST circuits in
the Model 145 are about twice as fast as the SLT circuits in the
Model 40.
• Space requirements for logic circuitry are reduced by the
significantly higher density of components per chip.
Monolithic Storage
Monolithic storage design incorporates the same concepts described
for monolithic logic. However, storage cells that are used to contain
storage bits instead of logic circuits are implemented on a chip. In
A Guide to the IBM System/370 Model 145 11