DECimage questions

[Joseph Zatarski]

 >I recently acquired a DECimage X terminal, which is theoretically a 
VXT-2000
 >with an add-on 2D accelerator. Unfortunately while the terminal is 
badges as a
 >DECimage it didn’t include the board, just a frame buffer.


That's unfortunate. My VXT2000 doesn't have that board either, I've 
always wondered how much it helps. I'm not too sure if the bottleneck is 
usually the 10mbit networking or the graphics. Probably depends a bit on 
whether you're using modern X11 applications or not. Modern stuff all 
likes to assume true-color (24bit or thereabouts) and render stuff 
locally and send it again to redraw, rather than rendering on the 
(remote) xterm it seems...


 >Does anyone have a spare DECimage board they’d be interested in 
parting with,
 >or know a reasonable place to obtain one?

Unfortunately, as I already stated I don't, and my only idea where to 
get one is ebay and similar sites, which I'm sure you already know.


 >How about other components for this machine? I have the AUI/thin 
Ethernet card
 >and wouldn’t mind replacing it with the AUI/twisted-pair card, and I’d 
also
 >like to max out the RAM: It has 2MB onboard and I have the riser card with
 >SIMM slots and one SIMM for an additional 4MB.

No clue where to get a twisted pair module, but mine has one. I 
currently have it hooked up to our thinnet segment though, and I've had 
it on our thicknet segment previously (now we have a proper VAXen 
occupying that transceiver).


 >It uses what I’m told are DEC MS200-AA (2MB) and DEC MS200-BA (4MB) 
modules,
 >which look like regular 72pin SIMMs. Are they special or are they 
compatible
 >with anything common?
 >
 >  — Chris
 >
 >Sent from my iPad


Here's where I can help you. The SIMMs aren't really anything special, 
you can use 2MB and 4MB modules. The VAX SOC in the VXT is slow enough 
that you probably don't have to worry about access time, so 60 or 70ns 
modules are probably both fine. If you don't have a 4MB module laying 
around, you can use an 8MB or 16MB module, but you have to install a 
wire from a ground pin to A10 on the SIMM connector and fix the presence 
detect bits, IIRC. (A0-A9 gives 1024 rows and columns, 1M-word per bank, 
4 bytes per word, so 4MB SIMM. DEC left the unused address lines 
floating, and that causes issues with bigger SIMMs). You can also 
install a single jumper IIRC to make 16MB SIMMs appear as 4MB, and 8MB 
SIMMs appear as 2MB (it's just grounding one of the PD lines, I don't 
remember which). The most you can fit into a VXT2000 is 18MB IIRC, 
that's 3 4MB SIMM, + 4MB on the riser itself + 2MB on the motherboard.


Lastly, you'll need the VXT2000 SW, which I extracted from some VMS 
(infoserver?) CDs several years ago. Someone put them up on 
terminals-wiki.org, so you can grab them there: 
http://terminals-wiki.org/collections/DEC/vxt2000.zip


VXT021KT10.SYS is the full blown VXT software including local side 
applications, like DECWindows etc.

VXTLDR021.SYS is some intermediate loader you can use to get an NFS swap 
file or something like that if you have an infoserver or VMS running the 
infoserver software IIRC.

VXTEX020A.SYS is *just* the X server IIRC, missing the local side 
applications but having a smaller memory footprint. This doesn't even 
have a window manager, so you'd have to use it with a remote one and set 
up XDMCP.


The terminals boot from MOP or TFTP/BOOTP with late enough firmware. MOP 
has a daemon available for linux and BSDs, if you'd like to go that 
route, but otherwise TFTP/BOOTP is probably better supported by modern 
infrastructure


Hopefully this was helpful. If you have any further questions, don't 
hesitate to ask. I'm probably one of a few people who bothers to keep a 
VXT around running, so I can probably answer most questions you might 
have about setup and operation.


Best Regards,

Joe Zatarski