2 layers50.8 × 50.8 mm
2 layers116.8 × 154.9 mm
Isa backplane
skiselev/isa8_backplane132ISA 8-bit Backplane
- Size
- 116.8 × 154.9 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 61
- Nets
- 83
- Pads
- 610
- Tracks, vias
- 2,599, 6
- Pours
- 3
- Routed
- Yes
- KiCad
- KiCad 4
- Created
- 6 Jan 2018
- Updated
- 2 Apr 2020
Overview
Isa backplane is an open-source printed circuit board by skiselev, from the skiselev/isa8_backplane repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 116.8 × 154.9 mm with 61 parts on 83 nets, routed with 2,599 tracks and 6 vias.
It is built around the 74HCT14D, 74HCT74D and LM7905CT. Its parts include 22 capacitors, 7 resistors, 4 diodes, 3 ICs and 3 connectors.
Main components
3
74HCT14D
SOP-14-40℃~+125℃ 1 1.9V~2.1V 2uA 34ns@4.5V,50pF 4.4V 4.5V~5.5V 400mV 4mA 4mA 500mV~600mV 6 74HCT Schmitt trigger SOIC-14 Inverters ROHSNexperiaInverters74HCT74D
SOIC-14-40℃~+125℃ 1 2 3.5pF 3ns 4.5V~5.5V 40uA 44ns@4.5V,50pF 4mA 4mA 59MHz 5ns 74HCT Series Asynchronous Complementary D-Type Rising Edge Set and Reset SO-14 Flip Flops ROHSNexperia74 Series
LM7905CT
TO-2200.5uVrms 0℃~+125℃@(Tj) 1 1.1V@(1A) 1.5A 1mA 25V 54dB@(120Hz) 5V Fixed Negative Over Current Protection、Short Circuit Protection、Thermal shutdown TO-220 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSTexas InstrumentsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
README
README.mdISA 8-bit Backplane
Compact ISA 8-bit Backplane board
Introduction
This backplane was designed as a smaller version of Micro ATX ISA Backplane. It can be used to build a compact IBM PC/XT compatible system using the Micro 8088 processor board, and the 8-bit ISA cards that I've designed: ISA Super VGA, ISA Floppy Disk and Serial Controller, XT-CF-Lite, ISA OPL2.
Specifications
- 7 ISA 8-bit (62 pin) slots
- ATX power supply connector, and ATX power control circuit
- Bi-color activity LED, that changes the color when the processor is executing the code (the color changes every time A7 address line changes its value)
- The form factor is (mostly) compatible with ATX / Micro ATX
- Pads for optional termination resistors
Hardware Documentation
Schematic and PCB Layout
Building Insturctions
Please refer to Building Instructions page for detailed instructions.
Jumpers, Connectors, and Switches
P1 - ATX power connector
| Pin | Description | Pin | Description |
|---|---|---|---|
| 1 | +3.3V power supply (not used) | 11 | +3.3V power supply (not used) |
| 2 | +3.3V power supply (not used) | 12 | -12V power supply |
| 3 | GND | 13 | Ground |
| 4 | +5V power supply | 14 | Power supply ON signal |
| 5 | Ground | 15 | Ground |
| 6 | +5V power supply | 16 | Ground |
| 7 | Ground | 17 | Ground |
| 8 | Power good (not used) | 18 | -5V power supply (not used)* |
| 9 | +5V standby power supply | 19 | +5V power supply |
| 10 | +12V power supply | 20 | +5V power supply |
Note: -5V is not provided by most ATX power supplies. It is generated using an on board voltage regulator instead
P2 - Power Switch connector
| Pin | Description |
|---|---|
| 1 | Ground |
| 2 | Power ON signal |
P3 - Power LED connector
| Pin | Description |
|---|---|
| 1 | LED+ |
| 2 | Ground |
SW1 - Power Switch
Press SW1 to turn power on or off. The SW1 is connected in parallel with P2
Bill of Materials - Version 1.0
ISA 8-bit Backplane project on Mouser.com - View and order all components except of the PCB.
ISA 8-bit Backplane project on OSH Park - View and order the PCB.
| Component type | Reference | Description | Quantity | Possible sources and notes |
|---|---|---|---|---|
| PCB | ISA 8-bit Backplane PCB - Version 1.0 | 1 | Refer to the RetroBrew Computers Board Inventory page for ordering information, or order from a PCB manufacturer of your choice using provided Gerber or KiCad files | |
| Integrated Circuit | U1 | 74HCT74, DIP-14 package | 1 | Mouser 595-SN74AHCT74N |
| Integrated Circuit | U2 | 74HCT14, DIP-14 package | 1 | Mouser 595-SN74AHCT14N |
| Integrated Circuit | U3 | LM7905C -5V voltage regulator | 1 | Mouser 512-LM7905CT |
| IC Socket | U1, U2 | DIP-14, 300 mil socket | 2 | Mouser 517-4814-3000-CP |
| LED | D1 | 3 mm, blue LED indicator | 1 | Mouser 696-SSL-LX3054USBD |
| LED | D2 | 3 mm, bi-color red/green LED indicator | 1 | Mouser 696-SSL-LX3054IGW |
| Diode | D3, D4 | 1N4148 | 2 | Mouser 512-1N4148 |
| Tactile Button | SW1 | 6 mm tactile button, straight | 1 | Mouser 653-B3F-1000 |
| Connector | P1 | 20 pin ATX power connector | 1 | Mouser 538-46015-2006 |
| Connector | P2, P3 | 4 pin header, 2.54 mm pitch | 2 | Mouser 649-68002-104HLF |
| Connector | BUS1-BUS7 | 62 pin card edge connector, 2.54 mm pitch | 7 | Mouser 571-6-5530843-5 |
| Capacitor | C1 - C19 | 10 uF, 16V, MLCC, 5 mm lead spacing | 19 | Mouser 810-FG28X5R1E106MR06 |
| Capacitor | C20 | 1 uF, MLCC, 5 mm lead spacing | 1 | Mouser 810-FG28X5R1H105KRT0 |
| Capacitor | C21, C22 | 0.1 uF, MLCC, 5 mm lead spacing | 2 | Mouser 594-K104K15X7RF53H5 |
| Resistor | R1, R2 | 10 kohm, through hole | 2 | Mouser 291-10K-RC |
| Resistor | R3 | 1 kohm, through hole | 1 | Mouser 291-1K-RC |
| Resistor | R4 - R7 | 470 ohm, through hole | 4 | Mouser 291-470-RC |
| Resistor Array | RR1 - RR5 | do not populate | Optional, should not be populated |
Parts
61| Qty | Value | Footprint | References |
|---|---|---|---|
| 19 | 10uF | my_components:Cap_Tant_508 | C1, C2, C3, C4, C5, C6, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19 +3 |
| 8 | HOLE | my_components:Hole_4mm | HOLE1, HOLE2, HOLE3, HOLE4, HOLE5, HOLE6, HOLE7, HOLE8 |
| 6 | BUSPC_HOST | my_components:Conn_Edge_ISA8 | BUS2, BUS3, BUS4, BUS5, BUS6, BUS7 |
| 4 | 470 | my_components:Res_762 | R4, R5, R6, R7 |
| 3 | 10k | my_components:Conn_SIL10 | RR1, RR2, RR3 |
| 2 | 0.1uF | my_components:Cap_Cer_508 | C21, C22 |
| 2 | 10k | my_components:Res_762 | R1, R2 |
| 2 | 1N4148 | my_components:Diode_762 | D3, D4 |
| 1 | 10k | my_components:Conn_SIL6 | RR4 |
| 1 | 1k | my_components:Res_762 | R3 |
| 1 | 1uF | my_components:Cap_Tant_508 | C20 |
| 1 | 4.7k | my_components:Conn_SIL6 | RR5 |
| 1 | 74HCT14 | my_components:IC_DIP14_300 | U2 |
| 1 | 74HCT74 | my_components:IC_DIP14_300 | U1 |
| 1 | ACTIVITY | my_components:LED_3mm | D2 |
| 1 | BUSPC_DEV | my_components:Conn_Edge_ISA8 | BUS1 |
| 1 | LM7905CT | my_components:IC_TO220-3_Horiz | U3 |
| 1 | OSHW-logo_silkscreen-front_8mm | OSHW-logo:OSHW-logo_silkscreen-front_8mm | G*** |
| 1 | POWER | my_components:Conn_Power_ATX_20pin | P1 |
| 1 | POWER | my_components:LED_3mm | D1 |
| 1 | POWER | my_components:Switch_Tactile_6mm | SW1 |
| 1 | POWER_LED | my_components:Conn_Pin_Header_2x1_2.54mm | P3 |
| 1 | POWER_SW | my_components:Conn_Pin_Header_2x1_2.54mm | P2 |
Questions
How big is the Isa backplane PCB?
It measures 116.8 × 154.9 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Isa backplane use?
61 parts, built around the 74HCT14D, 74HCT74D and LM7905CT. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Isa backplane KiCad files?
From the skiselev/isa8_backplane repository on GitHub, at the commit this page was made from: the board is KiCad/isa_backplane.kicad_pcb. PCBKit opens the board in the browser, with nothing to install.
Can I use the Isa backplane design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).
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