Thanks Josh!
If others (Don, Bob, and anyone else) who had changes they wanted to
make can take a look I'd appreciate it.
Thanks!
Todd
On Tue, Apr 28, 2015 at 10:05 PM, Crusty OMO <[email protected]
<mailto:[email protected]>> wrote:
Hi Todd,
Ok, I took a good look over the board, found 1 minor mistake. I
added some text to the silk screen layer to make it friendly.
I'm pretty much done, I can't see anything more to add or fix. I
counted the S-100 pins a few times, came up with 98 on one count,
but that's ok, we can just file off 1 of the pins and call it S-98.
Anyway, the new V4 files are on line at:
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder¶m=S-100%20backplane
Look for file S100 backplane V4.zip
If anyone wants to review them, please do. Otherwise... I think
I'm done.
Cheers,
Josh Bensadon
------------------------------------------------------------------------
Date: Mon, 27 Apr 2015 08:38:42 -0400
Subject: Re: [N8VEM-S100:6831] Re: Reorder of S-100 8-slot
Backplane PCB
From: [email protected] <mailto:[email protected]>
To: [email protected] <mailto:[email protected]>
Hi Josh,
Looks great to me! (I didn't look at the beta version yet though.)
I won't order until you give the "all clear" and I'm not in a hurry.
Thanks!
Todd
On Mon, Apr 27, 2015 at 12:19 AM, Crusty OMO
<[email protected] <mailto:[email protected]>> wrote:
Hi Todd,
Ok, I've finished rewiring the S-100 9-slot backplane. Please
do not build it yet... I want to look it over a few times,
since it's all hand routed, there might be problems. I also
want to pretty up the Silk Screen.
I've uploaded this beta version for anyone to help look for
problems. It's at:
http://n8vem-sbc.pbworks.com/w/browse/#view=ViewFolder¶m=S-100%20backplane
The file is called "S-100 Backplane v4-beta.zip"
Features of the board:
-Includes a custom spaced slot #1 for Front Panel on the IMSAI
computer (spacing = 1.04" instead of .75")
-Holes for mounting in either ALTAIR or IMSAI chassis
-There is a "no component" or Trace zone where the board would
rest on the rails of an ALTAIR computer.
-Bus traces are all on the bottom, top layer is primarily a
fill zone to help shield bus noise.
-2 connectors for power are available, the original 0.2"
spaced and a new 0.156" spaced for molex connectors.
-9 Slots in total.
-Board can be extended to another back plane by use of 3 x 34
pin ribbon cables
-The last board can be terminated.
-Reset switch moved to the front
-Grounding jumpers for 3 bus lines (as per previous versions)
Note, Termination uses the same holes that the ribbon cable
would, so it's either, extend the bus, or terminate the bus,
but not both.
Losses on the board....
-No fuses, I just couldn't squeeze them in... I hope this is
ok....
Regards,
Josh Bensadon
------------------------------------------------------------------------
From: [email protected] <mailto:[email protected]>
To: [email protected]
<mailto:[email protected]>
Subject: RE: [N8VEM-S100:6827] Re: Reorder of S-100 8-slot
Backplane PCB
Date: Sun, 26 Apr 2015 15:22:38 -0400
Hi Todd,
I'm well underway on rewiring the back plane. Since it's not
a complicated circuit, I am foregoing the schematic and just
doing the traces in manual mode. The first slot is spaced 1"
from the 2nd slot. Since I want to be able to cascade them,
and since the IMSAI board is wider, I moved the Termination to
the side and was able to add a 9th slot. The back 8 slots are
all 3/4" spaced. When you cascade the boards, the last slot
will be 2.25" from the 2nd slot on the next board, ie, skip 2
standard slots and resume 3/4" spacing.
The mounting holes for IMSAI are there, and even when
cascaded, they *should* all line up... I hope.
The mounting holes for ALTAIR are just the holes for the S100
connectors, but I was careful to not place components or
traces along the width of the two rails. The first slot
spaced 1" can be mounted into the existing holes, but new
holes will need to be drilled and tapped for the last slot. I
haven't removed my ALTAIR Back Plane to look (don't want to
upset all the wires, I heard on another post that these wires
break easily). But it appears they only drilled and tapped 4
holes on the rails anyway.
I hope to get this board done by tonight... but I recommend
you give me another week to look it over for errors.
Cheers,
Josh
------------------------------------------------------------------------
Date: Sat, 25 Apr 2015 16:03:29 -0400
Subject: Re: [N8VEM-S100:6825] Re: Reorder of S-100 8-slot
Backplane PCB
From: [email protected] <mailto:[email protected]>
To: [email protected]
<mailto:[email protected]>
Hi Josh,
Personally I'd prefer your #2, 8.5" with IMSAI and Altair holes.
It looks like fabricating the ALTAIR card guide mounts
wouldn't be too bad?
I'm probably not understanding something but couldn't we fix
issue with cascading the boards when the first slot is shifted
buy ensuring there's enough bare (or with only lower profile
parts than the connectors) after the last connector before the
edge of the board? Or does that screw up card guides or
something on some standard chassis?
Todd
On Sat, Apr 25, 2015 at 1:37 PM, Crusty OMO
<[email protected] <mailto:[email protected]>> wrote:
Guys,
Here's our first hurdle.... the ALTAIR back plane is 11"
wide. It is like this because the card slot guides are
screwed in from the bottom of the board. The IMSAI back
plane is only 8.5" wide.
The 8 slot board v2 is 7.25" wide.
It's not a problem to expand to 8.5", but 11" makes it
interfere with the IMSAI chassis by about .25"
Option 1. Make it 11", ready for the ALTAIR... IMSAI use
will require cutting the board.
Option 2. Make it 8.5", with IMSAI and ALTAIR holes,
ALTAIR use will just have to sacrifice the card slot guides.
Option 3. Make it 10.75" with a 8.5" irregular width for
the first slot, this will allow it to fit both systems,
but only allows a single screw to hold the 5/8" wide card
slot guide (otherwise needs 2 screws).
In Option 2, ALTAIR users can always create their own
cross beams using 1/2" aluminum angle to support the card
slot guides. Here's a picture of the first slot as
pictured from the back.
Look closely, you see 2 holes for card slot guides. Now
look at the rail that supports this board, it starts near
the S-100 connector, this board is supported by the holes
of the S-100 connector to two of these rails. New rails
can easily be added, see the multiple holes available on
the end of the chassis?
The NEXT hurdle involves the fact that the first slot on
the IMSAI is spaced just over 1" to slot 2. This is
because the first slot is meant to reach the front panel.
All the other slots are the regular 0.75" spacing... This
shouldn't be too much trouble, but it becomes trouble when
wanting to cascade these boards to make larger back
planes. There will need to be a sacrifice of one or two
slots to maintain correct spacing.
Thoughts?
Regards,
Josh
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