Help me! Before I take the plunge

[Ethan Dicks]

On Apr 1, 2005 9:25 AM, Doc Shipley <doc at mdrconsult.com> wrote:
>    Has anybody built the RX emulator described at
> http://www.chd.dyndns.org/rx02/
> 
>    The page says that RX02 support isn't finished, but that the RX01
> handler is working.

I have not built it, but I did have that project in mind when I
suggested that one could emulate an RX02 attached to a DECmate I.  One
advantage of the DECmate I CPU is that the controller for the second
drive pair is not an option; it's always present.  All one needs is a
straight-through DC37-to-DB25 cable for a single drive, or a
DC37-to-dual-DB25 Wye cable for both RX02s.

I do not have the cable myself (my DECmate I has only one set of
drives in the pedestal), but from reviewing the VT278 schematics, it
would be as easy to fabricate as a modem cable.  If one owned a
DECmate with a single set of drives, one could make the dual cable,
attach the 0/1 cable to the emulator, the 2/3 cable to the real
drives, and very easily take OS/278 images on a PC, boot to a prompt
on an emulated drive zero, then copy images from an emulated drive 1
to a real drive 2 or 3.  Once one is up and running on real RX02
media, one can swap the DB25 cables and have drives 2/3 emulated. 
Since I do not have OS/278, I might just do that some time.

I just wish there were an easy way to attach a real RX02 drive to a
modern machine (I know it can be done, but ISTR we established that a
parallel port wasn't quick enough... perhaps with some small amount of
external circuitry like a shift register...)

-ethan