Digital Data Communications Message Protocol - Revision history

Vaxorcist: /* Synchronous DDCMP Controller Capabilities */ Correction: No DDCMP support for DPV11 in VMS

2025-10-16T08:01:22Z

‎Synchronous DDCMP Controller Capabilities: Correction: No DDCMP support for DPV11 in VMS

2025-10-16T06:42:16Z

Fixed typo

2025-09-18T02:08:25Z

‎See also: +Installing and Testing Asynchronous DECnet over DDCMP between two MicroVAX Computers

2025-08-21T13:17:09Z

‎Asynchronous DDCMP: Correction of the first VMS version to support asynchronous DDCMP

2025-08-20T14:00:10Z

‎Asynchronous DDCMP: Clarified beginning of asynchronous DDCMP on VMS

2024-10-15T06:43:04Z

WAN usage of DDCMP added

2023-09-29T16:15:44Z

"Software Product Description" link added

2022-06-15T14:43:15Z

"using: VAX Wide Area Network Device Drivers Software" added

2022-06-09T10:17:22Z

‎Asynchronous DDCMP: Fixed typo

2022-06-09T10:08:08Z

Asynchronous DDCMP added

@@ Line 37: / Line 37: @@
 | VAXBI || [[DSB32]] || colspan="2" | X (supported DDCMP versions yet unknown) || - || - || X
 |-
-| QBUS || [[DPV11]] || colspan="2" | X (supported DDCMP versions yet unknown) || - || - || using: VAX Wide Area Network Device Drivers Software
+| QBUS || [[DPV11]] || colspan="2" | X (supported DDCMP versions yet unknown) || - || - || -
 |-
 | QBUS || [[DMV11]] || X || X || X || X || X

@@ Line 5: / Line 5: @@
 From 1983 onwards [[serial line]]s (using DDCMP) were step by step superseded by [[Ethernet]], which was superior in terms of speed and flexibility. DDCMP is nevertheless retained in current [[VMS]] DECnet versions, mainly because DDCMP was used still for [[wide area network]]s.
-DDCMP usually carried DECnet traffic, one known exception a late VAX version of the [[ULTRIX]] operating system:
+DDCMP usually carried DECnet traffic, one known exception is a late VAX version of the [[ULTRIX]] operating system:
 ''The [[DMV11]] is supported using TCP/IP and DECnet over full and half duplex point-to-point DDCMP sync lines.''

← Older revision		Revision as of 02:08, 18 September 2025
Line 92:		Line 92:

	DECnet/VMS only supported asynchronous DDCMP from version 4.0 onwards, i.e., 1984 at the earliest; it was improved with VMS V4.2 in 1985)		DECnet/VMS only supported asynchronous DDCMP from version 4.0 onwards, i.e., 1984 at the earliest; it was improved with VMS V4.2 in 1985)
		+
		+	==See also==
		+
		+	* [[Installing and Testing Asynchronous DECnet over DDCMP between two MicroVAX Computers]]

	==External links==		==External links==

@@ Line 91: / Line 91: @@
 DECnet-RSX (or DECnet-11M as it was called in the beginning) supported Asynchronous DDCMP at least from Version 2.0 (1979) onwards (see SPD), maybe even right from the start (Infos on DECnet-11M V1.x welcome!).
-DECnet/VMS only supported asynchronous DDCMP from version 4.7 onwards, i.e., 1987 at the earliest.
+DECnet/VMS only supported asynchronous DDCMP from version 4.0 onwards, i.e., 1984 at the earliest; it was improved with VMS V4.2 in 1985)
 ==External links==

@@ Line 91: / Line 91: @@
 DECnet-RSX (or DECnet-11M as it was called in the beginning) supported Asynchronous DDCMP at least from Version 2.0 (1979) onwards (see SPD), maybe even right from the start (Infos on DECnet-11M V1.x welcome!).
-DECnet/VMS started supporting Asynchronous DDCMP not until Version 4.7 as late as 1987.
+DECnet/VMS only supported asynchronous DDCMP from version 4.7 onwards, i.e., 1987 at the earliest.
 ==External links==

@@ Line 3: / Line 3: @@
 It was originally designed by [[Digital Equipment Corporation|DEC]] for the [[DECnet]] Phase I network [[protocol suite]], in 1974. It was retained in later versions of DECnet, with modifications and extensions.
-From 1983 onwards [[serial line]]s (using DDCMP) were step by step superseded by [[Ethernet]], which was superior in terms of speed and flexibility; DDCMP is nevertheless retained in current [[VMS]] DECnet versions.
+From 1983 onwards [[serial line]]s (using DDCMP) were step by step superseded by [[Ethernet]], which was superior in terms of speed and flexibility. DDCMP is nevertheless retained in current [[VMS]] DECnet versions, mainly because DDCMP was used still for [[wide area network]]s.
-DDCMP usually carried DECnet traffic, one known exception is [[ULTRIX]]:
+DDCMP usually carried DECnet traffic, one known exception a late VAX version of the [[ULTRIX]] operating system:
 ''The [[DMV11]] is supported using TCP/IP and DECnet over full and half duplex point-to-point DDCMP sync lines.''

@@ Line 9: / Line 9: @@
 ''The [[DMV11]] is supported using TCP/IP and DECnet over full and half duplex point-to-point DDCMP sync lines.''
-says: "The ULTRIX Operating System, Version 4.5 Software Product Description 26.40.32"
+says: "The ULTRIX Operating System, Version 4.5 [[Software Product Description]] 26.40.32"
 ==Synchronous DDCMP==

@@ Line 85: / Line 85: @@
 Asynchronous DDCMP uses simple asynchronous serial lines (such as [[DZ11]] or [[DLV11]]), which are mosty used for terminal communication.
-This led to the joke calling it '''"Poor Man's DECnet"''', because asynchronous serial line controllers were much cheaper then synchronous serial line or Ethernet controllers, and many computers already had a spare one available.
+This led to the joke calling it '''"Poor Man's DECnet"''', because asynchronous serial line controllers were much cheaper then synchronous serial lines or Ethernet controllers, and many computers already had a spare one available.
 The drawback of Asynchronous DDCMP is lower speed and less effectivity.

@@ Line 81: / Line 81: @@
 | DDCMP TRIBUTARY || Specifies that the line is a multipoint tributary end of a DDCMP multipoint group. You may specify only one circuit per TRIBUTARY line.
 |}
 ==External links==