The original meaning of the acronym (SFAIK) is given below and to the right. I suspect the Unisys "Single Point Operations" product was/is a backronym on this but the product is not a SPO in the traditional sense of the station to which the ATTACHSPOQ function has been assigned.
The SPO would be associated with a particular Operator Display Terminal (ODT), by assignment in the NDL (Network Definition Language) sources for the machine controlled.
The TD series (classic TD830 shown) were typically used in the seventies and early eighties. The "dumb" terminal is actually in the keyboard. I also used an "SR" station type with a more programmable microprocessor introduced after the TD.
This image shows a lot of reverse video, they were normally white text on black. I believe they also could be configured like a contemporary IBM 3270 for "greenscreen" green on black or amber. There also was an ET series (shown below), a more modern version of the TD monitor (shown above, an 800 I believe).
DGUI reference desktop version is Squeak 5.3 or later.
An experimental web spo is available here.
In my reimagined context, the domain GUI (DGUI) or SPO is just the smalltalk code which is developed to run in Squeak 5 or later from desktop or web.
- DCP Console on the model of the MCP console.
- FileList adapted for DCP file system model
- CommandShell adapted for mcpcms.
- The metaphor of the AC client, just the buttons, input box, and transcript in MVC or morphic.
"DGUI" could be somewhat misleading, since here "domain" refers only to the MCP/DCP aspect of domain space GUI, which is strictly smalltalk. More broadly anything that could run on a node could produce a native or web UI. It is a matter of aesthetics that the MCP GUI is limited to smalltalk.
"Supervisory Print Out"
In the original MCP based systems one or more consoles could function as the "SPO", the system operator interface. Originally it stood for "Supervisory Print Out" in the early MCP (presumably B5000 or possibly earlier). The ATTACHSPOQ DCALGOL function determines the current SPO.
In my homage it has become simply "SPO" ('spoh') for DCP/MCP, the set of squeak sources as described above as a UI for the dominion control program in the style of the Burroughs MCP. BTW, this is a good place to point out the diff between "Burroughs MCP", "Unisys MCP", and just "MCP". The second is the product marketed by Unisys which until recently I had not had hands on since my use of it as systems programmer in the 80s but which is now available as "MCP Express" that runs under Windows. The last is my invention which is no more than inspired by Burroughs MCP 4, the version of the Algol OS with which I had paid experience than 18/19 the current one in 2020/4718.