I've just bought the base unit (VS240) for a VT240 terminal on E-bay and
know little about it (OK, I know it's a DEC graphics terminal). Perhaps
somebody can enlightent me
1) One site i looked at said a VT240 is a monochrome unit, a VT241 is the
colour version. Is the only difference the monitor? Can I use a colour
monitor with my base unit?
2) On the back are obvious connectors for an RS232 port (DB25), current
loop (8 pin mate-n-lock). There's a DE9 labelled 'PR', presumably a
printer port, also RS232. A RJ11 keyboard socket, I assume an LK201 will
work here (yes?). A BNC which seems ot be composite mono video. And a
DA15 plug, also for a monitor. I assume a VR201 links here, or a V241
with the right cable. Also, can I connect the keybaord to, say, the back
of the VR201, or do I have to use the RJ11 on the terminal itself?
3) How much is known about the insides? Of course I've taken it apart.
It's really easy to get inside, just undo 2 screws on the bottom at the
very front and remove the top cabinet shell (lift it up from the front).
Then release 2 nylatch fasteners and lift up the metal screening cover.
The PSU (a switch-mode unit) is inside the cover. Reach inside and unlug
the PSU ribbon cable from the mainboard and remove the cover/PSU. The
mainboard comes out by releasing 3 more nylatch fasteners.
On this board, there's an 8085, 2681 (dual serial chip), 8251 (USART,
maybe used for the keybaord interface), 7220 (graphics chip) -- along with
what seemms to be much the same circuitry as a Rainbow colour card, there
are a couple of PALs, I've not checked to see if they're the same as the
ones in the 'bow. Pletny of RAM and ROM, and some glue logic. And another
40 pin chip, DC310. For some reason this is saying 'processor' to me. Is
it?
-tony