Storage Environment
The main storage communicates with:
1. The CCU via the storage control (SCTL)
2. The high-speed adapters via the direct memory access bus (DMA bus) through
the SCTL.
┌───────────────┐
│
Storage
│
1 card (STO)
└───────────────┘
4 or 8 Mbytes
&
6
┌─────────────────────────────────────┐
│
DMA Bus and Storage Control
│
1 card (SCTL)
└─────────────────────────────────────┘
&
&
│
6
│
┌─────────────┐
│
│ High─Speed
│
│
│
Buffer
│
│
│
&
│
1 card (PUC)
│
│
CCU
│
│
└─────────────┘
│
&
6
6
DMA Bus
IOC Bus
Direct Memory Access and Storage Control (SCTL)
The direct memory access and storage control functions are packaged on one card
(SCTL) and the main functions are the following:
Allocate main storage access to the different users (CCU via the cache
storage), and high-speed adapters via the DMA function of the SCTL).
Control the different storage operations and ensure data transfer integrity:
– CCU read and write
Write requests are buffered in SCTL so that the CCU and the storage oper-
ations can overlap.
– Cache storage line loading
– DMA burst transfers.
The data is aligned and temporarily stored in a buffer so as to optimize the
use of storage bandwidth.
Control the cache operations (line loading). Maintain cache consistency with
storage during DMA write operations, by means of a cache line invalidation
mechanism.
Check for unauthorized DMA write operations with a DMA storage protect
mechanism.
2-14
IBM 3745 Models 130, 150, 160, 170, and 17A: Hardware Maintenance Reference
Содержание 3745 Series
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Страница 21: ...3745 Models 130 150 160 and 170 Data Flow Chapter 1 General Information 1 3 ...
Страница 149: ...For RACs 241 to 244 ERR bits Data received from the adapter Chapter 3 Buses 3 57 ...
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Страница 255: ...The HPTSS in 3745 Models 130 150 160 and 170 Data Flow Chapter 5 High Performance Transmission Subsystem HPTSS 5 3 ...
Страница 303: ...Figure 6 8 Ring to Ring via Bridge Example 2 Typical Multi Floor Wiring Chapter 6 The Token Ring Subsystem 6 9 ...
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Страница 625: ...The ESS in 3745 Models 130 150 160 and 170 Data Flow Chapter 12 Ethernet Subsystem ESS 12 3 ...
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Страница 712: ...IBM Part Number 03F5010 Printed in Denmark by IBM Danmark A S ð3F5ð1ð SY33 2ð66 4 ...