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Drum Auxiliary Memory Subunit (DAMS) |
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|  MIL-D-81347C(AS)
Drum Auxiliary Memory Subunit (DAMS)
3.5.4.4.4
General Functional Requirements
3.5.4.4.4.1
The block diagram for the Drum Auxiliary Memory Subunit
The DAMS contains the Magnetic Drum Memory (MDM) and the Drum
(DAMS) is shown in Figure 151.
Controller. The DAMS shall receive control and data signals from the Computer via the MCP and
shall transmit control and data signals to the Computer and to the MCP. Manual test operation of the
DAMS shall be accomplished by placing the DAMS in the Off Line mode via the MCP. The DAMS shall
meet the following general performance requirements.
3.5.4.4.4.1.1
Capacity
The DAMS shall be capable of storing a minimum of 196,608
and a maximum of 393,215 computer words (30 bits each). Each data track of the MDM shall be
capable of storing 1024 computer words with the exception of the initial data track that is addressed.
The initial data track shall be capable of a maximum of 1023 computer w orals and an MDM preamble
word which shall precede the computer words.
3.5.4.4.4.1.2
Word Transfer Rate
The average data word transfer rate between the computer and
the DAMS of Logic Unit 4 shall not be greater than 60K words/second nor less than 30K words, `second.
3.5.4.4.4.1.3
Access Time
The time to access the location of and read/write the first data
word shall not exceed 30 milliseconds.
3.5.4.4.4.1.4
Error Rate
The error rate during read/write operations shall not exceed
10
a single error in 10 bits transferred to or from the DAMS. A single error is defined as any bit or
combination of bits being incorrect in a 30 bit data word transferred between the DAMS and the
computer.
3.5.4.4.4.1.5
Memory Protection
It shall be possible to protect the drum memory from writing
in a protected area by means of memory protect switches and Computer command. For memory protect
purposes, the memory shall be divided into blocks of 32, 768 consecutively addressable word locations.
3.5.4.4.4.1.6
System Initialization
Power to the DAMS shall be applied by means of the POWER ON/
OFF switch. During power initialization, the DAMS shall not transmit a Logic 1 on its Computer Con-
trol lines.
3.5.4.4.4.2
Drum Controller Requirements
The Drum Controller shall provide the interface for data handl-
ing and control purposes between the Magnetic Drum Memory and the Computer/MCP. The functional
flow diagram for this interface is shown in Figure 152. The basic requirements of the Drum Control-
ler shall be to provide the timing, control, and data handling logic needed for execution of the instruc-
tions from the Computer. The following paragraphs describe, in general terms, the basic require-
ments of the Drum Controller.
259
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