VAXstation 4000 VLC Basics: The VAXstation 4000 VLC is the smallest VAX available. It's the "pizza box" VAX, measuring only about 2 inches thick. The motherboard inside is only about 8" x 8"! If you're like me and remember the room filling VAXen, this one is quite the trip. It has an external SCSI bus and room for one internal SCSI hard disk. It can hold a maximum of 24MB of memory and has an AUI network connector. Since it's a VAXstation, it includes a video card and plugs for a mouse, monitor and keyboard. I'd like to pile 10 or so of these up and make a VAXcluster out of them. Here's a photo of the right side of the unit, remember, this is a VAXstation and is hence intended to be used with a monitor, mouse and keyboard. However, for the Marmotking, this blows the entire experience. It turns out that these items can be ignored (as you will learn below) and a good old VT-100 will do the trick. But first, it's important to explore the entire machine.
The reset switch is more of a "Halt" switch, I beleive (perhaps a DEC guy can clerify this). It takes you to a BIOS prompt where you can do all sorts of things like format hard drives, reboot the machine, change the boot device, etc. I usually do a shutdown of VMS and then press this button after the OS has stopped. When you get a new machine, you may need to use this button to get out of a failed boot. The "Headless" switch allows you to disable the video card, etc. It basically turns the system into a MicroVAX rather than a VAXstation. In the "Headless" mode, you need to connect an ansi terminal to the console serial port (more later). The switch should be in the up position (I thinks) to go "headless". Afterall, one doesn't buy a VAX to use a GUI. IMHO. Now, onto the more interesting stuffs. Below is a photo of the rear of the unit:
The status LEDs mainly show POST information. I haven't found them very useful. You'll have to consult the VLC service manual for more information (which, BTW, is available in the Marmotking's archive). You'll also notice the RGB monitor connections (sync on green, I think). The cables for these are very hard to find. They plug into an RGB (Sync on Green, I think) monitor which has the BNC style connectors on the back. My Iiyama Visionmaster Pro has this sort of connection on the back. I haven't tried it, since I'm not all that interested in running a GUI on my VAX. There are two serial ports on this critter. The "console" or "operators" port looks like an RJ-45, but don't be fooled! It's a special DEC connector called an MMJ connector (note the offset spot for the tounge). It also isn't exactly RS-232, since it uses a voltage differential scheme rather than a reference ground. However, it's implemented in such a way that it's RS-232 compatible. MMJ cables and adaptors are readily available to convert to DB-9 or DB-25 connectors. You can see that the second serial port is a standard DB-25 connector. I think this is DTE standard signaling. The important point here is that if you're going to go headless, you must connect a terminal to the MMJ connector first. This is the "operator's" terminal and the only one you can use to boot the system. You can connect a secondary terminal, printer, or modem to the DB-25, however. The SCSI connector is self-explanitory. It's your standard 50-pin, Centronix connector. Note that the internal SCSI controller occupies SCSI ID 6 and don't forget to terminate the external end of the bus. You can connect SCSI CD-ROM drives, DLT tape drives, hard drives, etc. to this connector. In fact, most 4000 VLC units you buy will come without a hard drive or internal hard drive mounting brackets. So, the only easy way to connect a hard drive may be an external SCSI drive unless you get really creative. It's important to note a few things here about CD-ROM and hard drives. Of course the DEC CD-ROM drives always work (RRD42/RRD44). However, they might be hard to come by. Many other SCSI CD-ROM drives will also work. I'm working on making a list. I've had many experiences where a CD-ROM drive works under VMS, but won't work in the BIOS when installing VMS. Also, some of the VAXstations have a 2GB limit on the size of the boot hard drive. This limit does not apply to the VLC. Lastly, before we delve into the inside of the machine, it's worth looking at the network connector. It's an AUI connector. This means that to use it with either twisted pair (Cat-5) or thin net (Coax) you need an transceiver. These too are readily available and should not cause fear. You are limited to 10Mb/sec, however. Now, onto the belly of the beast:
The rest is fairly straight forward. There's a 50 pin socket for a standard SCSI drive. The SIMMs are standard 72-pin SIMMs. This is the only VAX that uses the same standard SIMMs that you might find in a PC. Below is a close-up photo of these SIMMs, just incase you are looking to buy some or are a memory geek that knows what this stuff means. I looked up the part number and they are, "KMM5361000AG-8 BOH 4MB 72p 80ns 12c 1x4 Parity FPM SIMM J1, J2, J4, Samsung". Note that the VLC is limited to 24MB of memory. It is incapable of addressing more than that. With the 32-bit address space of the VAX architecture, this is a cryin' shame. (The Marmot King has noted that in the VLC service manual they state a 24MB maximum, but then show 32MB in their sample power-up screen. They also list the upper memory range as 0:1FF.FFFF, which is 32MB?! Something smells fishy as Lau Lau).
I pulled one of the SIMMs out to photograph the back side. You'll notice the DEC part number on a sticker there, "MS40-AA".
NOTE: If you want to see the notes I took when firing up this machine for the first time, you can see them by clicking here. |
