MS780 Memory System - Revision history

Jnc: /* External links */ +VAX-11/780 Installation Manual, has section on MS780

2024-05-15T18:54:33Z

‎External links: +VAX-11/780 Installation Manual, has section on MS780

Jnc: interleaving cleanup

2023-07-30T17:48:45Z

interleaving cleanup

Jnc: +MOS

2022-01-14T10:56:13Z

+MOS

Jnc: MS780-F and MS780-J also addnl array cards

2022-01-05T23:11:17Z

MS780-F and MS780-J also addnl array cards

Jnc: After a lot of dredging (the -A and -C are poorly covered in remaining docs)

2022-01-05T22:24:04Z

After a lot of dredging (the -A and -C are poorly covered in remaining docs)

New page

The '''MS780 Memory System''' was a [[Dynamic RAM|DRAM]] [[main memory]] system for the [[VAX-11/780]]. It was 64 [[bit]]s wide, to interface to the -11/780's [[Synchronous Backplane Interconnect]], and provided [[error-correcting code|ECC]] (8 bits/double-[[word]]), which could correct all single-bit errors.

An MS780 was comprised of a custom [[backplane]], a small group of control cards, and a variable number of array cards (between 2 and 16 per MS780), holding the DRAM [[integrated circuit|chips]]. There were two generations; the first included:

* '''MS780-A''' (sometimes given as MS780A): 4Kx1 DRAM chips, 64KB per array card
* '''MS780-C''': 16Kx1 DRAM chips, 256KB per array card

(The MS780-B and MS780-D are additional array cards for the MS780-A and MS780-C.) The second generation includes:

* '''MS780-E''': 64Kx1 DRAM chips, 1MB per array card
* '''MS780-H''': 256Kx1 DRAM chips, 4MB per array card

For the original release of the -11/780, with the MS780-C, this produced a maximum of 512 KB per MS780. The -11/780 supported up to 4 MS780 subsystems, for a maximum of 2MB with fully populated MS780-C's.

It was possible to [[interleaving|interleave]] two MS780's to improve performance.

==Implementation==

All versions were implemented on [[DEC card form factor|super hex]] cards ([[Digital Equipment Corporation|DEC]]'s first use of this form factor), mounted in a custom 20-slot backplane.

The initial versions, the MS780-A and MS780-C, included:

{| class="wikitable"
! Slot !! Board !! Acronym !! Function
|-
| 20 || M8214 || MSB || SBI Interface
|-
| 19 || M8213 || MCN || Control and Timing
|-
| 18 || M8212 || MDT || Data Paths
|}

Slots 2-17 held 256-Kbyte M8210 (MS780-C) or 64-Kbyte M8211 (MS780-A) array cards; a minimum of two, in slots 16 and 17, were required. The backplane was [[DEC part number]] 70-13625.

The later versions, the MS780-E and MS780-H, were implemented using a different card set mounted in a different custom 20-slot backplane (DEC part number 70-19729-00):

{| class="wikitable"
! Slot !! Board !! Acronym !! Function
|-
| 10 || M8375 || MCN || Control (lower)
|-
| 11 || M8376 || MSB || SBI Interface
|-
| 12 || M8375 || MCN || Control (upper)
|}

Slots 2-9 and 13-20 held 1-Mbyte M8373 (MS780-E) or 4-Mbyte M8374 (MS780-H) array cards; a minimum of two, in slots 9 and 13, were required.

{{semi-stub}}

==External links==

* [http://www.bitsavers.org/pdf/dec/vax/780/EK-MS780-TD-001_MS780_Technical_Manual_197808.pdf MS780-E MS780-H Memory Subsystem Technical Description] (EK-MS780-TD-001)
* [http://www.bitsavers.org/pdf/dec/vax/780/MP01759_MS780H_Jun84.pdf 11/780 Memory Assembly (MS780-H) Field Maintenance Print Set] (MP01759)
* [https://decdoc.itsx.net/dec94mds/1178xrva.txt VAX 11/780 & 11/782 Revision Control Document] - contains module revision histories for all variants of the MS780
* [https://www.computerhistory.org/collections/catalog/XD148.80B VAX prototype memory SBI board M8214]

[[Category: VAX Memories]]

← Older revision		Revision as of 10:56, 14 January 2022
Line 1:		Line 1:
−	The '''MS780 Memory System''' was a [[Dynamic RAM\|DRAM]] [[main memory]] system for the [[VAX-11/780]]. It was 64 [[bit]]s wide, to interface to the -11/780's [[Synchronous Backplane Interconnect]], and provided [[error-correcting code\|ECC]] (8 bits/double-[[word]]), which could correct all single-bit errors.	+	The '''MS780 Memory System''' was a [[Metal Oxide Semiconductor\|MOS]] [[Dynamic RAM\|DRAM]] [[main memory]] system for the [[VAX-11/780]]. It was 64 [[bit]]s wide, to interface to the -11/780's [[Synchronous Backplane Interconnect]], and provided [[error-correcting code\|ECC]] (8 bits/double-[[word]]), which could correct all single-bit errors.

	An MS780 was comprised of a custom [[backplane]], a small group of control cards, and a variable number of array cards (between 2 and 16 per MS780), holding the DRAM [[integrated circuit\|chips]]. There were two generations; the first included:		An MS780 was comprised of a custom [[backplane]], a small group of control cards, and a variable number of array cards (between 2 and 16 per MS780), holding the DRAM [[integrated circuit\|chips]]. There were two generations; the first included:

@@ Line 55: / Line 55: @@
 * [http://www.bitsavers.org/pdf/dec/vax/780/EK-MS780-TD-001_MS780_Technical_Manual_197808.pdf MS780-E MS780-H Memory Subsystem Technical Description] (EK-MS780-TD-001)
 * [http://www.bitsavers.org/pdf/dec/vax/780/MP01759_MS780H_Jun84.pdf 11/780 Memory Assembly (MS780-H) Field Maintenance Print Set] (MP01759)
 * [https://decdoc.itsx.net/dec94mds/1178xrva.txt VAX 11/780 & 11/782 Revision Control Document] - contains module revision histories for all variants of the MS780
 * [https://www.computerhistory.org/collections/catalog/XD148.80B VAX prototype memory SBI board M8214]
 [[Category: VAX Memories]]

@@ Line 15: / Line 15: @@
 For the original release of the -11/780, with the MS780-C, this produced a maximum of 512 KB per MS780. The -11/780 supported up to 4 MS780 subsystems, for a maximum of 2MB with fully populated MS780-C's.
-It was possible to [[interleaving|interleave]] two MS780's to improve performance.
+It was possible to [[memory interleaving|interleave]] two MS780's to improve performance.
 ==Implementation==

@@ Line 6: / Line 6: @@
 * '''MS780-C''': 16Kx1 DRAM chips, 256KB per array card
-(The MS780-B and MS780-D are additional array cards for the MS780-A and MS780-C.) The second generation includes:
+(The MS780-B and MS780-D are additional array cards for the MS780-A and MS780-C, respectively.) The second generation includes:
 * '''MS780-E''': 64Kx1 DRAM chips, 1MB per array card
 * '''MS780-H''': 256Kx1 DRAM chips, 4MB per array card
 For the original release of the -11/780, with the MS780-C, this produced a maximum of 512 KB per MS780. The -11/780 supported up to 4 MS780 subsystems, for a maximum of 2MB with fully populated MS780-C's.