ISA Backplane

MicroATX ISA Backplane - Version 1.1

This backplane supports bus width up to 16 bits. It has onboard POST code indicators as well as a -5V regulator allowing you to use it with modern power supplies.

Available For Sale

[For sale at my eBay store]

• Bare PCB
• Individual Components
• Full Component Kit

Features

• ATX Power Connector
• 16 Bit ISA bus

Required Tools

• Soldering Iron,
• Rosin core solder
• Wire cutters
• Pliers
• Multimeter (optional: if you want to check for shorts)

Assembly Steps

Start with the shorter components first. This way you can lay the board down flat on the table and be able to solder them in. The taller components go next. The recommended order is as follows.

1. IC Sockets

component type	reference	Name	Qty
socket	U5, U6, U7	14 pin 300 mil DIP socket	3
socket	U1, U2	16 pin 300 mil DIP socket	2
socket	U3, U4	20 pin 300 mil DIP socket	2

2. Capacitors

component type	reference	Name	Qty
PCB		PCB	1
Capacitor	C1 - C51	10 uF ceramic, 5.08 mm lead spacing	51
Capacitor	C52	1 uF ceramic, 5.08 mm lead spacing	1
Capacitor	C53 - C59	0.1 uF ceramic, 5.08 mm lead spacing	7

Polarity doesn't matter unless you are using electrolytic ones.

3. ISA Slots

component type	reference	Name	Qty
Connector	BUS1 - BUS8	Edge Connector 98 Pin	8

4 LED Lights

component type	reference	Name	Qty
Diode	D1 - D5	5 mm LED	5

5 ATX Power connector

Board connector as it would appear looking down on the board. The plastic tab will be on the left side towards the inside of the board.

Note also the power connector pins will need to be bent slightly with pliers as the pin spacing on the PCB is a little wider than the power connector spacing.

component type	reference	Name	Qty
Connector	P3	ATX Connector	1

LED Display Configuration

7-Segment Decoders and Matching Displays

The ISA Backplane board supports a variety of 7-segment decoders and common anode / common cathode type LED displays. Please use the following table to determine the proper configuration.

74LS48, 74LS248 Limited - Displays distinct figures for codes A-F Common cathode 1-2 2-3 2-3 No

7-Segment Decoder Type	Hexadecimal Support	Matching Display Type	J2	J3	J4	Built in current limiters
74LS47, 74LS247	Limited - Displays distinct figures for codes A-F	Common anode	2-3	2-3	2-3	No
CD4511, MC14511, 74HCT4511	No - Displays nothing (blank) for codes A-F	Common cathode	1-2	2-3	1-2	No
Mitel MD4311BE	Yes	Common cathode	1-2	2-3	1-2	No
DM9368	Yes	Common cathode	1-2	1-2	2-3	Yes
DM9370	Yes	Common anode	2-3	1-2	2-3	No
DM9374	Limited - Displays distinct figures for codes A-F	Common anode	2-3	1-2	2-3	Yes
D345D	Yes	Common anode	2-3	1-2	2-3	No
D346D	Yes	Common anode	2-3	Trim2	2-3	Yes
D347D	Limited - Displays distinct figures for codes A-F	Common anode	2-3	1-2	2-3	No
D348D	Limited - Displays distinct figures for codes A-F	Common anode	2-3	Trim2	2-3	Yes

POST Codes and what they mean

[Reference information available here]

Power On and Test

The goal is to identify any short circuits that would cause problems. Before powering on the device check to see if there are shorts across any of the rails of the PCB.

1. Turn on the backplane and use a volt meter to check voltage across the PCB including the expansion slots.
2. Plug in the ATX power connector and the PCB and the standby light should go on.
3. Then click the power button and the power lights should go on.
4. The -5V regulator is option and if your power supply does not provide -5V then you can solder that in as well. Once the regulator is installed the -5V light should go on as well.