14 Jul
2011
14 Jul
'11
9:18 p.m.
On Thu, Jul 14, 2011 at 8:19 PM, Vincent Slyngstad <vrs at msn.com> wrote:
Without checking the printset, I was going to say one 6402 UART drives
the printer, the other drives the console terminal.
I don't recall either, and my DM-I is in another place, so I can't check.
-ethan
From: "Brent Hilpert": Thursday, July 14,
2011 5:20 PM
Yep. No electrical or logical difference, but using WPS with a WPS
keyboard is easier than using a keymap on paper.
Received a Decmate I / VT278 recently (PDP8 micro
in VT100 cabinet), sans
keyboard and disk drives...
I suppose a keyboard may not be too difficult for
someone to obtain, the
disk drives I expect will be less likely; or can anyone comment on what it
will take to make this a half-way-useable PDP8 system?
I think you are looking basically for a VT-100 style keyboard, though the
authentic one would have the "Gold" key in the upper left of the keypad.
As for "disk drives", the standard thing is
a pair of RX01 floppy
drives, interfaced with a slightly different cable.
The VT78 came with RX01s. The VT278 came with RX02s. Same cable for
all "desktop" 8" drives... DC37-to-DB25 for one drive pair,
DC37-Y-to-two-DB25 for two pairs. Inside the pedestal is a small
board that has a DB25 facing the outside world, and a "normal" Berg
40-pin cable to go to the drive controller. It's the same board
that's in the skinned MINC floppy case, too (same DB25 external
pinout).
?To be completely
authentic they should be in a tower that is holding the VT278 up at desk
height :-).
I have a pedestal - it has one RX02 set (same guts as a rack-mount
RX02, but mounted differently) and room for another.
I expect that RX02 with the internal switch set for
RX01-only mode should
also work fine.
Yes.
?RX02 were used on a lot of PDP-11 systems, and so
aren't
too difficult to find.
They did make a lot of them.
I suppose one
of the 6402s drives the printer port, what does the other
do? The COMM-ports board that sits beside the processor board is missing.
Any problem with blowing ROMs to turn the printer port into a boot/download
port?
Have a look at the drawings at ? ?pdf/dec/pdp8/cmos8/
on your favorite bitsavers.org mirror.
From what I can see on MP00900_VT278_may81.pdf
40/74, it looks like
E46 is the COMM-port and E45 is dedicated to a serial intefrace to the
keyboard. When powered
on the PWR-OK & CPU-OK LEDs light up and the CRT filament
lights up, but there is no sign of any raster. Kind of looks more like the
monitor is dead...
I'd have to look into that. ?The DM II and DM III display an error code on
the screen, but I don't know offhand about the older VT-278.