Subject: Re: 8/L repairs

From: Charles <[email-masked]>
Date: Fri Mar 28 15:15:39 2003

On Fri, 28 Mar 2003 12:58:47 -0600, you wrote:

>A) What rev M706 card do you have?

Rev. K. That's one reason it took me a while to find, since the
only schematics available seem to be the first revision (A?)

>B) Would you write up where you attached your pullups?

Check the schematic, it was on the preset lines to the 7474
containing stop bit 1 and stop bit 2...

>Are you using a microprocessor on your DF32x4? FPGAs?  PALs?  TTL?

Plain old 74LS and a Dallas Semi DS1258 128kx16 NVRAM.

>How are you handling the cabling issue?

Cables :)
(I also laid out a PCB to plug in the backplane and accept a
standard 40 pin IDC header connector). Had five fabricated and
made 3 foot ribbon cables.

>  Do you have a way to load
>the emulated disk devices "out of band"?  (i.e., can you get data into
>it in any way other than the databreak interface to the -8?)

No, I took the DF32 manual and copied the specs as closely as
possible. The 8/L should "think" it has a real DF32 and three
expansion DS32's attached.
>
>> [demime 1.01a removed an attachment of type image/jpeg which had a name
>> of mvc-457e.jpg]
>
>What's the picture of?
>
>-ethan

Pic is of the DF32x4 on the workbench. I'll send you a copy
direct.
-Charles

---

From: Ethan Dicks <[email-masked]>
Date: Mon Mar 31 19:05:44 2003

> containing stop bit 1 and stop bit 2...

That's good enough to find it.  Thanks.

> Plain old 74LS and a Dallas Semi DS1258 128kx16 NVRAM.

Interesting.  Can't wait to see the plans.

> >How are you handling the cabling issue?

:-) indeed. 

> made 3 foot ribbon cables.

Sounds great.  If several folks wanted to get into a bulk-buy, we
could probably get a stack of those cheap.  I was getting 12" long
boards with inches of gold fingers (GG2 Bus+ - 100-pin Zorro plus
16-bit ISA) for well under $20 each, q 100., with silk screen and
solder mask.  Panelled out, something like this could be as cheap
as a few bucks each in sufficient quantity.

No matter what the device (external memory, external disk, etc.),
I'd *love* to have a stack of inexpensive paddle cards to interconnect
a variety of devices I have.  Another bonus is that the modern
end of the cable does *not* have to resort to hard-to-find DEC-style
slots and fingers.  40-pin IDC stuff is about as cheap as it gets.

Also, it might be interesting to experiment with them as a base for
simple prototype modules (I keep kicking around an idea for a
crystal-controlled M452 replacement for higher-than-110-baud use
on an M706/M707 set) - just attach the "device" to the 40-pin
spot and go.

I could probably put dozens of these to use in the first few months,
all by myself.  I would probably even be willing to act as a point-of
contact on a group order.  The more the merrier.

> expansion DS32's attached.

Well... that's easy to build, anyway.  I suppose it would be easy enough
to make a parallel-port NVRAM programmer...

> Pic is of the DF32x4 on the workbench. I'll send you a copy

Thanks,

-ethan

---

From: Lawrence LeMay <[email-masked]>
Date: Mon Mar 31 19:32:00 2003

> contact on a group order.  The more the merrier.

As long as they were desigend to be flexible, so that traces could be
cut and jumper wires installed to make whatever type of cable connector
you might need, such as Omnibus or unibus connectors, they would be
very useful. I'd like to have a few myself, just to make a M993 cable,
or maybe omnibus extender cables, etc.

The company you were thinking of with the breadboards is Douglas
Electronics. These are scans of information i recieved from them.

  http://www-users.itlabs.umn.edu/~lemay/computers/dec_breadboards.html

-Lawrence LeMay
 [email-masked]