Useful Bits of Information

Of course as you collect VAXen you will begin to pick up various bits of information that is either hard to locate, or just not generally well known. Part of my motivation for putting these pages on the Web has been to take such information and ensconce it in the genetic memory of the collective.

So far we have:

Upgrading a 4000/300 to a faster VAX

This question arises because the VAX 4000/300 uses a different type of memory than the 4000/400 and above and the backplane (the thing the cards plug into) was modified to support doing such upgrades. If you take the boards out of your VAX 4000 and look at the part number on the backplane, if it is 54-19354-01 then you can. If it has an earlier number then you need to upgrade the backplane before upgrading the system.

Finding a MicroVAX II Ethernet Address

Unlike later versions of the MicroVAX family where you can just type 'SHO ETHER' and they will tell you their Ethernet MAC address, the MicroVAX II (and VAXStation II, MicroVAX II/GPX, etc) has a very primitive console monitor without fancy commands. That does not mean however that you have to pull out the board and read the sticker on it to get this information. You can use the monitor to Examine the contents of I/O memory on the Qbus where the DEQNA and DELQA keep their MAC address as follows:

The letters in bold you type and the purple results are the ones that are important.

>>> e/w/p 20001920
 P 20001920 FF08
>>> e/w/p
 P 20001922 FF00
>>> e/w/p
 P 20001924 FF2B
>>> e/w/p
 P 20001926 FF04
>>> e/w/p
 P 20001928 FF0A
>>> e/w/p
 P 2000192A FF6A

This VAX has an Ethernet MAC address of 08:00:2B:04:0A:6A

What is the FASTEST VAX? 

If you have to ask, then the answer is none of them are faster than a modern CPU (CISC or RISC). The VAX excelled at I/O bandwidth for its CPU size. 

However, in specific cases you can answer the question. So for the Q-Bus based VAXen (of which all of the MicroVAXen had their roots, the fastest true Q-Bus processor is the KA660. 

This processor was a drop in replacement (with faster memory) for all Q-bus VAXen, from the MicroVAX II up through the MicroVAX 3900. When a machine is running the KA660 it is called the VAX 4000/200. (and strangely it is slower than the VAX 4000/100 :-)

When this board was used to upgrade a BA23 or BA123 based VAX the cabinet kit takes three of the back panel slots, one for the CPU bulkhead, one for the Ethernet port, and one for the DSSI disk port.

Within my collection, the 4000/90 is my fastest VAX in terms of raw "VUPS" at 40 VUPS. The only thing faster would be a 4000/96. On the Q-bus side of the house the 4000/200 is the fastest "pure" Q-bus system and the 4000/700a is the fastest single box (but not pure Q-bus) VAX. 

That 1GB Disk Limit on VAXStations and MicroVAXen

[This taken from the VAX5 entry in the VMS FAQ. How long Compaq er HP will maintain this is anyone's guess --Chuck]

System disks larger than 1.073 gigabytes (GB) -- 1FFFFF hexadecimal blocks -- are not supported on any member of the VAXstation 3100 series and on certain older members of the MicroVAX 3100 series, and are not reliable on these affected systems. (See below to identify the affected systems -- the more recent members of the MicroVAX 3100 series systems are NOT affected.) 

Various of the SCSI commands used by the boot drivers imbedded in the console PROM on all members of the VAXstation 3100 series use "Group 0" commands, which allow a 21 bit block number field, which allows access to the first 1fffff hexadecimal blocks of a disk. Any disk references past 1fffff will wrap -- this wrapping behavior can be of particular interest when writing a system crashdump file, as this can potentially lead to system disk corruptions should any part of the crashdump file be located beyond 1.073 GB. 

More recent systems and console PROMs use "Group 1" SCSI commands, which allow a 32 bit block number field. 

There was a similar limitation among the oldest of the MicroVAX 3100 series, but a console boot PROM was phased into production and was made available for field retrofits -- this PROM upgrade allows the use of the "Group 1" SCSI commands, and thus larger system disks. There was no similar PROM upgrade for the VAXstation 3100 series.

 Systems that are affected by this limit: 

A PROM upgrade for these specific systems is (was once) available. The VAXStation 3100/M76 user's manual is online.

What are the pin-outs of my DECServer 700-16 ?

Which 1 2 3 4 5 6 7 8
Dalco blue orange black red green yellow gray brown
Fry's blue orange black red green yellow brown white
-> DB9 5-GND 3-TXD 5-GND 7-RTS 8-CTS 2-RXD 6-DSR 4-DTR
-> DB25 7-GND 2-TXD 7-GND 4-RTS 5-CTS 3-RXD 6-DSR 20-DTR
-> DB9 8-CTS 6-DSR 2-RXD 5-GND 5-GND 3-TXD 4-DTR 7-RTS
-> DB25 5-CTS 6-DSR 3-RXD 7-GND 7-GND 2-TXD 20-DTR 4-RTS
-> DB25 7-GND 3-RXD 2-TXD 5-CTS 4-RTS


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