VT78 - lots of questions - test-drb@ccmp.vtda.org

24 Dec 2000

...
 From: pete(a)dunnington.u-net.com (Pete Turnbull) 
...
 I assume that the difference between RX8E (=
RXV11/RX11) mode, and RX28
mode, is the denisty supported?  ie, RX28 mode makes the drives behave as
RX02 rather than RX01?  Did'nt I read somewhere that some VT78s (or was it
 only DECmates?) can use RX02 mode?
 For the PDP-8 it is mostly a software issue.  I tried booting the VT78
...
 from a RX02 in RX28 mode and it worked with a RX02
version of OS/8. 
...
 Well, before I go that far, I might try to get 8"
drives running on an old
PC that has an XT controler which *should* do SD, I think.  Can I use
something like PUTR to create a disk that way?
 I think so if the floppy chip supports SD.  I have not tried.

From: "Mike" &lt;dogas(a)bellsouth.net&gt;

...

I'm glad this thread came up.  I have a WT/78.  Is it the same machine as
the VT/78?  And also having a RX-02 and no interconnecting cable or
software, I eagerly await the pinout specs too and have an outstanding wish
for software.

From what I understand they were basically the same thing except the ROM module that
plugs on the back may support different things but I
am not really familiar with the models.  WD was listed as a WS with
COS support.  WS may only work with WPS.  I didn't see a WT.

Do you have anything else to write to the RX02 from? If so you can
write my images, if not I can make you a copy, email me if needed. I will 
buzz out the VT78 floppy cable.

This is the pinout I got by buzzing out the adapter cable I made to go 
...
 from the DB25 on my RX02 to the 40 pin cable from the
RX8E.  If the pinout was in a document I can't find it, I may of
gotten the pinout by buzzing out the cable in the drive.  
Pins 10,11,23, and 24 are not connected in the cable from my VT78 but  
pin 25 is present.  I don't remember why my adapter cable has
extra pins connected.

DB25    40 pin header
 1         3 C
14	   4 D
 2         7 E
15         8 F
 3        11 M
16        12 N
 4        15 S
17        16 T
 5        19 W
18        20 X
 6        25 CC
19        24 BB
 7        27 EE
20        28 FF
 8        31 KK
21        32 LL
 9        35 PP
22        36 RR
10        37 SS
23        38 TT
11        39 UU
24        40 VV

12,13,25 Not connected.

40 pin connector is numbered

1 (A)     39 (UU)
2 (B)     40 (VV)