boards:s100:backplanev4:historical [RetroBrew Computers Wiki]

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Historical S-100 Backplane V1 (6-slot), V2 & V3 (8-slot) Archive ======
{{:boards:s100:backplanev4:historical:img_9402.jpg?direct&600|}}

<note important>The information below is an archive of everything that was in the 'S-100 backplane' folder of the legacy wiki.  It is included mainly as a reference for owners of the older V1/V2/V3 boards.  Please see the [[boards:s100:backplanev4:start|S-100 Backplane V4 - 9-slot]] page for the current board</note>

===== S-100 Backplane Build Notes by Don Caprio=====
==== Step 1 ====

Gather the parts. I use Jameco, Digi-key and Mouser. Unfortunately one source does not have all the parts. I had to place orders at both sources to get all the parts needed. Primary source was Jameco and whatever they did not carry I used Digi-Key. The downside of ordering resistors at Jameco is you have to order in quantities of 100.

I've prepared a Bill-of-materials (BOM) file for use on the Digi-key web site. This makes ordering simple. There are two BOM's. One with the S100 Edge connectors and one without. You have to have a Digi-Key account to use the BOM's. Click on the 'My Digi-Key → Parts List/BOM Manager → Create New Parts List (Upload File)' link.

Note: Digi-Key carries everything for this project except the resettable fuses.

{{:boards:s100:backplanev4:historical:digikey_s100_bom.txt|}} <- Digi-Key BOM with S100 edge connectors

{{:boards:s100:backplanev4:historical:digikey_s100_withoutedgecon_bom.txt|}} <- Digi-Key without edge connectors.

As of Jan 2011 the parts with S100 connectors runs about $149, and $24.00 without S-100 female connectors.

Anchor Electronics has the S100 connectors for $3.95 each, not as nice, but still very serviceable.

==== Step 2 ====

Get your magnifying glass out and inspect the PCB board. Your are looking for any solder bridges or holes that may have gotten filled by the solder mask.

==== Step 3 ====

This may seem like an un-needed step but I can assure you it is well worth it. Inspect the parts that you received very closely. Just because the packaging says it's a specific part it may not be. Errors happen. Installing the incorrect components could result in your project not working which may take hours and hours to fix. Take your time and double check the component when mounting it in the PCB. The extra time is well worth it.

==== FAQ ====

=== Calibrating the Trimmer POT ===

The trimmer pot is used to calibrate the active terminator circuit. Basically you set the pot at mid setting and then power up the circuit. Use your VOM to measure the voltage on the signal pins and adjust the pot so they settle at 2.65V to 2.7V. That is dead center of the TTL “no mans land” between high and low. The active terminator keeps all the signals solidly there until a bus buffer/transceiver pulls them high or low. This really reduces bus ringing and suppresses noise quite a lot.

=== What are The P2, P3, P4 and P5 Headers used for? ===

Those connectors are for the “to be announced” ECB to S-100 bridge board. Once that is done it will allow N8VEM ECB systems to expand to S-100 and vice versa. Until the PCB is done though I would not fill the connectors since it is going to be a while.

=== What are The JP1, JP2, and JP3 jumpers for? ===

These correspond to the IEEE-696 ground pins. Some boards require them and other boards use them for different signals. The early S-100 boards are not fully IEEE-696 standard compliant. You can see these jumpers on the various S-100 boards on the left hand side near the edge connector.

=== P12 ===

This is for an external reset switch.

=== How do I orient the LED pins? ===

The pin 1 of LEDs is square. That’s true for all parts so you can easily identify pin #1. You can pick the LED orientation off the schematic once you know pin #1 location. The bar on the LED symbol matches the flat part on the LED so that is also helpful.

===== S-100 Backplane Improvements & Fixes =====
<note important>Most of these fixes were implemented in the V4 board.</note>
<file>
Fixes:
1. re-work fuses to current limit the boards
2. Fix Q1 transistor orientation. Involves a 180 degree rotation. 

Improvements:
1. add pin notations to silkscreen for pin 1 and board orientation 

More notes:

Bob Bell:
The power connector is easy if you use the terminal blocks like those found in the current Jameco catalog page 63.
They "snap" together, so two 3-position blocks fits perfect.
1.  Board thickness needs to be reduced.  I had a hard time with the RNets.
2.  One of the transistors has it's silk-screen mirrored.
3.  The fuses are only protecting the LEDs. 
4.  The 0.3" lead-to-lead pitch on the 1/4 Watt resistors is too narrow.
5.  The schematics are rather difficult to follow.

Jeff Albrecht notes:
Add holes to make board directly fit into ALTAIR & IMSAI Chassis.

Josh Bensadon notes:
-Add edgecard pads or headers to make boards stack up in tandem (after note by Curt Mayer for an 18 slot) 
-Perhaps include 2 types of power connectors?
</file>

===== Photo Gallery =====
{{gallery>historical?&0 }}

===== Files =====
{{filelist>historical:*&style=table&tableheader=1&tableshowdate=1&tableshowsize=1}}