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The '''Private Memory Interconnect (PMI)''' bus was a high-performance memory bus, a variant of the [[QBUS]], introduced with the [[KDJ11-B]] [[PDP-11]] CPU. | The '''Private Memory Interconnect (PMI)''' bus was a high-performance memory bus, a variant of the [[QBUS]], introduced with the [[KDJ11-B]] [[PDP-11]] CPU. It also provides means for the CPU and a [[KTJ11-B]] [[UNIBUS]] adapter to communicate in providing UNIBUS service. | ||
For data transfer, PMI provides two primary modes; i) single- and double-word | |||
data reads, and single-word and single-byte reads; ii) block mode, which can read up to 16 words. When operating with a KTJ11-B, it provides means for UNIBUS devices to perform DMA cycles (mapped to the full 22-bit address space via a UNIBUS map), and to interrupt the CPU. | |||
The PMI uses the [[CD interconnect]] specified for QBUS backplanes to carry PMI-specific signals; PMI also uses other existing QBUS signals (e.g. BDAL00-21), on their standard pins. Use of the standard CD interconnect means that PMI-systems (such as a [[PDP-11/83]] can be constructed with a standard [[Q/CD backplane]], a KDJ11-B CPU card, and one or more [[QBUS memories|PMI memories]]. | |||
==Pinout== | |||
PMI pins are identified in the standard [[UNIBUS]] manner; there are four connectors, A-B; pins on the component side are 1, those on the solder side are 2. Pins are identified by the '[[DEC alphabet]]', A-V, with G, I, O and Q dropped. | |||
The tables below show the pins used for normal PMI master-slave cycles (as in | |||
the PDP-11/83), and those used to communicate with the KTJ11-B UNIBUS adapter (PDP-11/84 and PDP-11/94 only). | |||
===Master-slave signals=== | |||
{| class="wikitable" | |||
! Pin !! Signal !! Meaning | |||
|- | |||
CE1 || PBCYC || Indicates a PMI cycle | |||
|- | |||
CR1 || PBSY || PMI busy | |||
|- | |||
DC1 || PBYT || Used with BWTBT to indicate type of PMI cycle | |||
|- | |||
CP1 || PBLKM || Indicates a PMI block mode transfer (i.e. multi-word) | |||
|- | |||
CB1 || PSSEL || Slave select | |||
|- | |||
DB1 || PWTSTB || Write strobe | |||
|- | |||
CJ1 || PSBFUL || Slave buffer full | |||
|- | |||
CM1 || PRDSTB || Read strobe | |||
|- | |||
CH1 || PHBPAR || High byte parity | |||
|- | |||
CK1 || PLBPAR || Low byte parity | |||
|} | |||
===UNIBUS adapter communication signals=== | |||
{| class="wikitable" | |||
! Pin !! Signal !! Meaning | |||
|- | |||
CF1 || PUBSYS || UNIBUS adapter present | |||
|- | |||
DD1 || PMAPE || Enable UNIBUS map for UNIBUS->PMI | |||
|- | |||
CD1 || PUBMEM || CPU access to UNIBUS | |||
|- | |||
CV1 || PUBTMO || UNIBUS timeout | |||
|} | |||
{{pdp-11}} | {{pdp-11}} | ||
[[Category: Bus Architectures]] | [[Category: Bus Architectures]] | ||
Revision as of 16:16, 5 June 2016
The Private Memory Interconnect (PMI) bus was a high-performance memory bus, a variant of the QBUS, introduced with the KDJ11-B PDP-11 CPU. It also provides means for the CPU and a KTJ11-B UNIBUS adapter to communicate in providing UNIBUS service.
For data transfer, PMI provides two primary modes; i) single- and double-word data reads, and single-word and single-byte reads; ii) block mode, which can read up to 16 words. When operating with a KTJ11-B, it provides means for UNIBUS devices to perform DMA cycles (mapped to the full 22-bit address space via a UNIBUS map), and to interrupt the CPU.
The PMI uses the CD interconnect specified for QBUS backplanes to carry PMI-specific signals; PMI also uses other existing QBUS signals (e.g. BDAL00-21), on their standard pins. Use of the standard CD interconnect means that PMI-systems (such as a PDP-11/83 can be constructed with a standard Q/CD backplane, a KDJ11-B CPU card, and one or more PMI memories.
Pinout
PMI pins are identified in the standard UNIBUS manner; there are four connectors, A-B; pins on the component side are 1, those on the solder side are 2. Pins are identified by the 'DEC alphabet', A-V, with G, I, O and Q dropped.
The tables below show the pins used for normal PMI master-slave cycles (as in the PDP-11/83), and those used to communicate with the KTJ11-B UNIBUS adapter (PDP-11/84 and PDP-11/94 only).
Master-slave signals
CE1 || PBCYC || Indicates a PMI cycle CR1 || PBSY || PMI busy DC1 || PBYT || Used with BWTBT to indicate type of PMI cycle CP1 || PBLKM || Indicates a PMI block mode transfer (i.e. multi-word) CB1 || PSSEL || Slave select DB1 || PWTSTB || Write strobe CJ1 || PSBFUL || Slave buffer full CM1 || PRDSTB || Read strobe CH1 || PHBPAR || High byte parity CK1 || PLBPAR || Low byte parity| Pin | Signal | Meaning |
|---|
UNIBUS adapter communication signals
CF1 || PUBSYS || UNIBUS adapter present DD1 || PMAPE || Enable UNIBUS map for UNIBUS->PMI CD1 || PUBMEM || CPU access to UNIBUS CV1 || PUBTMO || UNIBUS timeout| Pin | Signal | Meaning |
|---|
