MA780 Multiport Memory Option
The MA780 Multiport Memory Option was a MOS DRAM multi-port memory main memory system for the VAX-11/780; it allowed creation of multi-processor systems such as the VAX-11/782. It was 64 bits wide, to interface to the -11/780's Synchronous Backplane Interconnect (SBI), and provided ECC (8 bits/double-word), which could correct all single-bit errors.
An MA780 system was comprised of:
- the main MA780 unit, which contained a custom backplane holding i) a small group of control cards, and ii) a variable number of array cards (between 1 and 8 per MA780), holding the DRAM chips; and
- in each connected CPU (between 2 and 4), an MA780-C Port Interface, held in another, smaller custom backplane, which connected the main MA780 unit (up to two different ones per MA780-C) to the host CPU's SBI.
With the 256-Kbyte M8210 array card (shared with the MS780-C), this allowed a maximum of 2MB per MA780. The -11/780 thus supported up to 2 MA780 subsystems, for a maximum of 4MB with fully populated MA780's.
The main MA780 was implemented on super hex cards, mounted in a custom 20-slot backplane. The cards were:
|1||M8210||MAY||Memory Array (optional)|
|9||M??||MAP||Selective Map Cache (optional)|
|10||M8261||MPS||Multiport Port Synchronizer|
|11||M8212||MDT||Memory Data Paths|
|12||M8260||MAT||Multiport Array Timimg|
|13||M8259||MPC||Multiport Port Control (Port 3 - optional)|
|14||M9045||BDI Connect (rear)|
|15||M8259||MPC||Multiport Port Control (Port 2 - optional)|
|16||M9045||BDI Connect (rear)|
|17||M8259||MPC||Multiport Port Control (Port 1)|
|18||M9045||BDI Connect (rear)|
|19||M8259||MPC||Multiport Port Control (Port 0)|
|20||M9045||BDI Connect (rear)|
Slots 1-8 held 256-Kbyte M8210 array cards; a minimum of one, in slot 8, was required.
The MA780-C was mounted in a custom 20-slot backplane. The contents were:
|2||M9040/M8258||SBI Terminator / Multiport Port Interface (optional)|
|3||M8258||Multiport Port Interface|
|4||M9045||BDI Connect (rear)|