Data Bus And; Block Control; Storage Addressing And Data Paths Of Typical Installation - Control Data 3100 Reference Manual

DATA BUS AND'S' BUS
The Data Bus provides a common path over which data must flow to the storage,
arithmetic, console typewriter and I/O sections of the computer. These sections are
connected in parallel to the Data Bus. During the execution of each instruction, Main
Control determines which data transfer path is activated.
An odd parity bit is generated for the lower byte of each word as it leaves the DBR
during I/O operations. In the case of a 3107 I/O Channel, parity for the upper byte of
data is generated in the channel itself rather than in the Data Bus.
The S or Address Bus is a data link between Main Control and storage for transmitting
storage addresses. Inputs to the S Bus are from the P register, F register, Block Con-
trol and the Breakpoint circuits. Figure 1-5 illustrates the relevance of the Data Bus
and S Bus in a typical 3100 installation.
Storage Address S Bus
-
I
T
I
3108 3104
13200~;:-1
3109
I 3101 I
Storage Computer
.. -----+1
Desk
I
Storage
Module (Includes Standard
I
I
Module
I Console
I
(4K)
4K Memory)
!_
i'1>.!i~n~~J
(8K)
1
Data Bus
J
--
I
T
-
I
T
3106 3106
3106 3106
(may be a single 3107)
4 bidirectional data channels
Figure 1-5. Storage Addressing and Data Paths of Typical Installation
BLOCK CONTROL
Block Control is a unique control section within a 3100 Computer. In conjunction with
the Register File and program control, it directs the following:
• External equipment I/O
operations~
• SearchlMove instruction processing.
• Real-Time clock referencing.
• Console typewriter I/O operation.
• Storage in the Register File.
All operations with Block Control result from requests to Block Control. The requests
are classified into two types: program requests and block operation requests.
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