IBM System/370 Manual page 11

Specifically, the Model 165 offers the following advantages over
Models 65 and 75:
Larger Processor (Main) Storage Sizes
Storage sizes of 512K, 102QK, 1536K, 2048K, and 3072K are provided.
The Model 65 offers a maximum of 1024K. Larger Model 165 storage sizes
are available at smaller cost increments, and additional storage can
contribute significantly to system performance and capabilities.
The addition of more processor storage provides the Model 165 user
with the ability to:
• Execute more jobs concurrently, including new application and
integrated 7000-series emulator jobs
• Add and expand applications, such as graphics, teleprocessing,
time sharing, remote job entry, and data based, that require large
amounts of storage
• Use higher level language translators and linkage editors that
provide more functions and execute faster
• Execute larger processing programs without the necessity of overlay
structures
• Allocate more processor storage to language translators and sorts
to improve their execution speed
• Use more and larger I/O buffers to speed up input/output operations
and optimize use of direct access storage space
• Include system generation options that improve control program
performance and support additional functions
Expanded Channel Capabilities
The fast internal performance of the Model 165, together with
expanded use of multiprogramming, requires that more data be available
faster.
The Model 165 offers more and faster channels than the Model 65,
twelve instead of seven, and 1.5 MB and 3.0 MB data rates on the 2880
in addition to a 1.3 MB rate on the 2860.
The channel features of the Model 165 provide:
• A significantly higher attainable aggregate data rate than provided
by the Model 65 to balance the high performance capabilities of
the Model 165
cpu.
A twelve-channel Model 165 system can support
I/O
conf~gurations
with an aggregate data rate in excess of 9-MB.
• Attachment of high-speed direct access devices, such as 3330 and
2305 facilities, that will increase I/O throug:1put
• Channel throughput increase capabilities via use of block
multiplexing with rotational position sensing to improve effective
data transfer rates
Faster I/O Devices with Increased Data Capacity
The 3330 and the 2305 facilities offer significantly faster data
access than the 2314 facility and 2301 Drum Storage because of higher
data transfer rates, faster rotation, and new features. Rotational
position sensing and multiple requesting used with block multiplexing
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