Table of Contents
Advertisement
2-10
Theory of Operation
The case has a door which can be opened to provide access to the upper 9 slots or removed to
provide access to all 12 slots. A dc box fan attached to one end of the stack provides cooling air to
the boards.
The stack interconnects with the computer motherboard via two 25-pin connectors and a 50-
conductor input/output processor (lOP) cable. The 25-pin connectors on the bottom of the stack
interconnect with connectors on the computer motherboard when the stack is positioned in the
computer. These connectors provide power and control signals and send self-test information to the
system control module (SCM). The internal lOP ribbon cable connects the motherboard to the lOP
board in slot #2. Additional lOP cables interconnect lOP boards and the computer rear panel.
Stack Configurations
The stack has 12 slots numbered from 1 to 12, with slot # 1 the bottom slot and slot # 12 the top. All
slots are interconnected by the memory processor bus via the stack motherboard. The memory
processor bus (MPB), which has 32 data/address lines and 12 control lines, interconnects all boards
to the lOP board(s). The lOP board in slot #2 is connected to the internal lOP cable which is routed
to the motherboard.
Four types of boards can be used in the stack: central processor unit (CPU), input/output processor
(lOP), and random access memory (RAM). A load board may also be required, depending on stack
configuration. All are described in following paragraphs.
The stack can be configured with various combinations of boards. One or two CPU boards can be
added. One or two lOP boards can be added. Any number of RAM boards are allowed. However,
if 1 Megabyte RAM boards are used, they must be used in pairs.
The following rules must be observed for all configurations:
• Slot # 1 must always contain a CPU card.
• Slot #2 must always contain an lOP card.
• If there is one additional lOP board, it must be in slot #3. If there are two additional lOP
boards, they must be in slots #3 and #4.
• No empty slot is permitted between two finstrates.
• 1 Megabyte RAM boards must be used in pairs (2, 4, 6, 8, or 10).
• A load board must be used in the top occupied slot (adjacent to the RAM boards) any tirrle the
stack configuration is:
a. One CPU, one lOP, and one 512K RAM card.
b. RAM is composed of all 1 Megabyte RAM boards and there are less than 6 RAM boards.
(The load board is not required if other types of RAM are included in the stack,or there
are more than six 1 Megabyte RAM cards in the stack.)
Minimum and maximum configurations are as follows:
Finstrate
Minimum
Maximum*
CPU
1
3
lOP
1
3
RAM
2
10
*
Maximum of 12 finstrates per stack.
Advertisement
Table of Contents
