Building the Apple II Rev 0 Reproduction Kit: Complete Assembly Walkthrough

The Apple II Rev 0 is the rarest version of Steve Wozniak's original 1977 design — manufactured for only a few months before the Rev 1 replaced it. This RetroMakerKits reproduction is a faithful replica: same layout, same through-hole construction, same 8-slot backplane. Every component is sourced and tested before shipping so you spend your time building, not hunting for dead chips.

The fully assembled Apple II Rev 0 reproduction motherboard. Eight expansion slots, ceramic RAM, and the characteristic layout of the earliest Apple II boards.

⚠️ Critical Power Warning — Read This Before Anything Else

Do not power the motherboard on or off by plugging and unplugging the DC output of the power supply.

Connecting or disconnecting the DC side of a switching power supply generates high-voltage transient spikes. On this board, those spikes go directly into the RAM chips and will destroy them instantly and permanently. There is no protection circuitry. One wrong power cycle and the RAM is gone.

The only safe way to power on, power off, or reboot:

• Switch at the AC inlet — wall socket switch, power strip switch, or the switch on the power supply's AC input
• Never touch the DC connector while the supply is energised
• Never "reset" by briefly disconnecting and reconnecting the DC output

This applies every single time you power cycle the board — not just during assembly. Always.

What This Kit Is

The Apple II Rev 0 was manufactured for only a few months in 1977 before the Rev 1 replaced it. The differences are subtle — a few component substitutions, minor PCB revisions — but Rev 0 boards are significantly rarer and more sought-after by collectors. Running a Rev 0 is the closest you can get to the machine that shipped in those first brown boxes.

This reproduction uses the original schematic and PCB layout as its basis, with the minimum modifications necessary to work with currently available components. The visual appearance and all functional characteristics are preserved.

Before You Start: Pre-Build Checklist

• Count your ICs first. Passive components include a small number of spares. ICs are packed exactly — one per position. If an IC is missing, contact us before soldering anything else.
• All components are through-hole. The original 1977 board used no surface-mount parts, and neither does this reproduction.
• Have your tools ready: temperature-controlled soldering iron, thin 60/40 or no-clean solder, flux, solder wick, multimeter, IC extraction tool, anti-static mat and wrist strap.

Recommended Soldering Order

Solder in this sequence — lowest profile first, ICs last:

1. Resistors
2. Diodes
3. Inductors
4. Ceramic capacitors
5. Electrolytic capacitors (observe polarity)
6. Transistors
7. IC sockets — all of them, before any IC goes in
8. Connectors and pin headers
9. 50-pin expansion slot connectors

Insert ICs only after all sockets are soldered and you have verified power rail voltages on the empty board. Inserting an IC into a board with a solder bridge on a power rail will destroy that IC.

IC Substitutions in This Kit

Several components used in the original 1977 board are no longer manufactured or difficult to source reliably. The following substitutions are made — functionality is identical unless noted:

• H3, H4, H5: Original 8T97 bus drivers replaced by 74LS367. Pin-compatible, same function.
• 257 multiplexers: Only the two 257 chips near the keyboard connector use the original 257. The remaining three 257 positions use 157 chips instead. This is a known-good substitution for this design.
• F11, F12 (ROM positions): These use ROM adapter sub-boards. Other ROM sockets can be left empty unless you are adding additional ROM.
• B2 (oscillator): The original oscillator circuit is not compatible with modern crystals. A 74LS86-based adapter module generates the clock signal instead. See the Clock Circuit section below.
• D1, E1, F1 (memory select): These use plug-in sub-boards for the memory select logic.
• A5 (character ROM): Uses an adapter board. Position A5 requires both a DIP-24 socket and a DIP-16 socket.

Socket Orientation and Type

IC socket orientation: with the board held upright, the notch on almost all sockets faces downward. Verify each position against the silkscreen before soldering.

• Round-hole (turned-pin) sockets are required for A5 DIP-24, A5 DIP-16, and J14 DIP-16. These positions are accessed frequently and round-hole sockets provide more reliable long-term contact.
• Standard flat-leg sockets are fine for all other positions.
• Notch direction: With the board upright, almost all IC sockets have their notch facing downward. Inserting a chip backwards will destroy it on power-up.
• Pin headers and resistor arrays: The square solder pad marks pin 1. Match it to the dot or bar on the component.

Clock Circuit — Do Not Solder This Area

The original Apple II oscillator circuit area. Leave this entire area completely unsoldered — the original design is not compatible with modern crystals.

Do not solder any components in the oscillator circuit area. The original design used a specific crystal combination that is no longer compatible with available modern crystals. Leave it completely empty.

Instead, the kit uses a compact clock module based on the 74LS86 that plugs into the B2 socket position and generates the correct 14.318 MHz system clock. No configuration required.

Component Identification Guide

Any PCB position with a white outline box but no printed value: solder a 104 (100 nF) ceramic capacitor. These are bypass capacitors for IC power pins — there are many of them.

• White outline, no value printed: 104 ceramic capacitor (100 nF). Decoupling capacitors on IC power pins.
• Positions circled in red on the PCB diagram: 224 capacitor (220 nF). Check the silkscreen to distinguish from 104 positions.
• Diodes: Common small-signal diodes (1N4148 or equivalent) can substitute where original 1N914 is specified. Observe polarity — cathode band must match the silkscreen.
• Resistors and larger capacitors are marked with their values on the silkscreen. Verify with a multimeter before soldering.

Power Supply Connection

Power connector orientation: the raised ridge on the connector body faces upward. Reverse connection means reversed voltages — this destroys multiple ICs immediately.

1. Verify AC compatibility. The included supply is configured for the Chinese standard AC mains. Verify the input voltage label and use an appropriate adapter or replacement supply if you are outside China.
2. Measure DC output with a multimeter before connecting the board. Verify each voltage rail (+5 V, +12 V, −12 V) is within specification.
3. Connector orientation: The power connector has a raised ridge on one side. That ridge faces upward. Reverse connection is instant and irreversible damage — there is no polarity protection.
4. Re-check everything once the connector is seated before applying AC power for the first time.

Keyboard Converter Connection

Check pin 1 alignment carefully before seating the connector. The marked edge must align with the pin 1 marker on the board header.

The keyboard converter connects via a flat cable. Orientation is not symmetric — connecting it backwards will damage the converter. Match the red wire or marked edge of the cable to the pin 1 marker on the PCB header before seating.

First Boot

With all ICs seated, power verified, and connections checked, apply AC power from the AC side only.

• All ICs should be cool to the touch within the first 30 seconds. If any IC is noticeably hot, power off immediately from the AC side. A hot IC indicates a fault — reversed chip, solder bridge, or defective component.
• The CPU and RAM chips will warm slightly during normal operation. Burning hot is not normal.
• With a floppy disk controller card installed: the system boots automatically from the virtual floppy drive. The included image contains Apple DOS 3.3 and vintage games in the game directory.
• Without a floppy controller: after the display initialises, press Ctrl + Backspace to enter the onboard Integer BASIC interpreter.

Troubleshooting

• No video output: Check the video connector orientation, verify the character ROM adapter at A5 is fully seated, and confirm the clock module at B2 is correctly installed.
• Garbage on screen: Most commonly a RAM fault. Power off, re-seat the RAM chips one at a time. A chip that is warm while others are cool is defective — contact us for a warranty replacement.
• System freezes randomly: Check all IC sockets for cold joints. Re-flow suspicious joints with fresh flux.
• Keyboard not responding: Verify keyboard cable orientation. A reversed cable is the most common cause of keyboard failure on first boot.
• Won't boot from floppy: Confirm the disk controller card is fully seated in slot 6. The virtual floppy image must contain a valid Apple DOS 3.3 boot sector.

Warranty

This kit carries a one-year warranty covering manufacturing defects: defective ICs, faulty PCB traces, and components that fail under normal operating conditions. The warranty does not cover damage from incorrect power connection, reversed chips, or DC-side power cycling.

If you receive a defective component, contact us before attempting any repair. We will provide a replacement component. Do not attempt to desolder ICs without contacting support first — desoldering from this board without the right tools damages pads.

Resources

• GitHub Repository — PCB files, full image gallery, and component notes
• RetroMakerKits Docs — Assembly documentation, errata, and additional guides

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