# SDH-100 Bill of Materials
# Overview
The SDH-100 ships as a kit. All parts are supplied, and the build is straightforward through-hole soldering — every through-hole IC comes with a socket, so no chip is soldered directly to the board. The surface-mount components are factory-assembled on the PCB (see Notes for the list), so no SMD work is required.
If you are new to kit soldering, the recommended tools page and the Kit Assembly soldering video on YouTube (originally made for the IMSAI 8080 replica, but the same tools and techniques apply) are good starting points.
# Notes
# Microcontroller module
The board's microcontroller is a Pimoroni PGA2350 (powered by an RP2350B). It is supplied with the kit, together with the pin headers needed to mount it on the main PCB. It does not appear in the interactive BOM because it ships as a pre-assembled module rather than a set of discrete parts.
# Surface-mount components
The following SMD parts come already assembled on the PCB — no SMD soldering is required during kit build. They are listed here for reference only.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 5 | SN74LVC8T245 (level translator) | TSSOP-24, 0.65 mm pitch | U1, U2, U3, U4, U14 |
| 1 | NCP1117-3.3 (regulator) | SOT-223-3 | U5 |
| 1 | DS3231MZ (RTC) | SOIC-8, 1.27 mm pitch | U15 |
| 1 | PCA9306D (level translator) | SSOP-8, 0.65 mm pitch | U16 |
| 1 | MCP23017 (I/O expander) | SOIC-28W, 1.27 mm pitch | U17 |
| 1 | USB Micro-B socket (Amphenol 10104110) | SMD signal pins + through-hole shield tabs | J10 |
# Optional bleed resistors (R6, R7, R8)
R6, R7, and R8 are optional 1/2 W bleed resistors. Install them only if your S-100 power supply does not already provide bleed resistors of its own — they help dissipate any residual charge held in the power-supply capacitors after the supply is switched off.
# Interactive Bill of Materials
The interactive bill of materials lets you click components in the schematic to locate them on the PCB (and vice versa). It opens in a new tab.