Difference between revisions of "MB20 core memory"
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The '''MB20''' was a [[core memory|core]] [[main memory]] system for the later [[PDP-10]]s, principally the mid-period [[KL10]]. An MB20 contained up to four memory controllers<sup>*</sup>, each with up to four 32KW storage modules, for a maximum of 512KW; [[parity]] is provided to protect the memory contents. The [[access time]] is 1.04 µseconds, and the [[cycle time]] is 1.92 µseconds (both for the first [[word]] in a 4-word block, using four-way [[interleaving]]). | The '''MB20''' was a [[core memory|core]] [[main memory]] system for the later [[PDP-10]]s, principally the mid-period [[KL10]]. An MB20 contained up to four memory controllers<sup>*</sup>, each with up to four 32KW storage modules, for a maximum of 512KW; [[parity]] is provided to protect the memory contents. The [[access time]] is 1.04 µseconds, and the [[cycle time]] is 1.92 µseconds (both for the first [[word]] in a 4-word block, using four-way [[interleaving]]). | ||
| − | It connected to the KL10's so-called internal memory bus, the S-Bus; controllers 0 and 1 are connected to S-Bus 0, and controllers 2 and 3 to S-Bus 1. For interleaving, each controller is configured as to which addresses (out of the 4 in an S-Bus block) it will respond to; both 2-way and 4-way interleaving require controllers to be set to 'odd' or 'even'. In 4-way interleaving, in addition to two controllers being actuated at the same time, each controller can start two modules reading at the same time. | + | It connected to the KL10's so-called internal memory bus, the [[PDP-10 Memory Bus|S-Bus]]; controllers 0 and 1 are connected to S-Bus 0, and controllers 2 and 3 to S-Bus 1. For interleaving, each controller is configured as to which addresses (out of the 4 in an S-Bus block) it will respond to; both 2-way and 4-way interleaving require controllers to be set to 'odd' or 'even'. In 4-way interleaving, in addition to two controllers being actuated at the same time, each controller can start two modules reading at the same time. |
<nowiki>*</nowiki> - <i>DEC documentation conflicts on this; the 'MB20 Internal Memory Unit Description', EK-MB020-UD-001, December 1976, says optionally four (pg. 1-1) - and has generally been followed for this writeup; the 'DECsystem-10 DECSYSTEM-20 Processor Reference Manual', AA-H391A-TK, July 1980, says two (pg. G-18).</i> | <nowiki>*</nowiki> - <i>DEC documentation conflicts on this; the 'MB20 Internal Memory Unit Description', EK-MB020-UD-001, December 1976, says optionally four (pg. 1-1) - and has generally been followed for this writeup; the 'DECsystem-10 DECSYSTEM-20 Processor Reference Manual', AA-H391A-TK, July 1980, says two (pg. G-18).</i> | ||
Revision as of 14:52, 24 October 2022
The MB20 was a core main memory system for the later PDP-10s, principally the mid-period KL10. An MB20 contained up to four memory controllers*, each with up to four 32KW storage modules, for a maximum of 512KW; parity is provided to protect the memory contents. The access time is 1.04 µseconds, and the cycle time is 1.92 µseconds (both for the first word in a 4-word block, using four-way interleaving).
It connected to the KL10's so-called internal memory bus, the S-Bus; controllers 0 and 1 are connected to S-Bus 0, and controllers 2 and 3 to S-Bus 1. For interleaving, each controller is configured as to which addresses (out of the 4 in an S-Bus block) it will respond to; both 2-way and 4-way interleaving require controllers to be set to 'odd' or 'even'. In 4-way interleaving, in addition to two controllers being actuated at the same time, each controller can start two modules reading at the same time.
* - DEC documentation conflicts on this; the 'MB20 Internal Memory Unit Description', EK-MB020-UD-001, December 1976, says optionally four (pg. 1-1) - and has generally been followed for this writeup; the 'DECsystem-10 DECSYSTEM-20 Processor Reference Manual', AA-H391A-TK, July 1980, says two (pg. G-18).
See also
External links
- MB20 Internal Memory Unit Description (EK-MB020-UD-001)
- MB20 Field Maintenance Print Set (MP00179)
