The 74xx Chip Library

The parts palette's CHIPS folder holds a broad shelf of 74xx-family DIP logic — everything from a single quad NAND gate up to octal shift registers and 4-bit counters — every one with a datasheet-accurate pinout and, where the simulator supports it, real behavior you can wire up and run. A separate Memory group sits alongside it for address-indexed ROM/RAM parts, which get their own dedicated page. This page is a tour of what's on the shelf and how to read a chip's pin-assignments window once you've placed one.

Combinational gates

The basic gate families — the classic 7400-series building blocks:

Alongside them, the inverter and buffer/bus-driver parts:

Sequential & MSI parts

Everything with internal state, plus the mid-scale-integration decoders and multiplexers that build address/data logic around them.

Flip-flops & latches

The 74LS73, 74LS75, and 74LS76 reproduce their datasheet's non-standard power-pin placement — real parts don't always put VCC and GND on the package corners, and neither do these.

Counters & shift registers

Decoders & multiplexers

Arithmetic, comparison & encoding

Memory chips

The Memory group carries the address-indexed parts: a couple of generic teaching ROM/SRAM chips plus real-shaped EEPROM/EPROM/SRAM parts on wider DIP packages. Reads and writes are wired up the same way as every other chip in the catalog, but a non-volatile chip's contents live in a real file on disk and are programmed through a dedicated in-app tool rather than by the circuit itself. See Memory Chips & the Inspector for the full story — file-backing, the external programmer, and the hex/ASCII inspector.

The sim-ready badge

Every chip in the palette that has real behavior wired up — its truth table or state machine, not just its pinout — carries a small sim badge next to its name. Hover it for a reminder: "Behavior defined — ready for the simulator." In practice this covers the whole 74xx shelf on this page; you'll only ever see a chip without the badge if a future part ships with a pinout but no behavior yet.

The pin-assignments window

Double-click any chip — or a package-footprint discrete like the bar8iso LED bar, which seats and rotates exactly like a DIP chip even though it isn't one — to open its pin-assignments window: a small, floating window separate from the main desk, showing the physical DIP layout with the notch at the top, pin 1 at the top-left, and pin numbers wrapping down the left side and back up the right to the highest pin at the top-right, exactly as printed on the part.

For a real chip this layout is always the canonical, fixed arrangement — it matches the physical part regardless of how you've flipped it on the desk, because a real chip's pin-1 dot is a physical feature of the package, not something rotation changes. bar8iso is the one exception: it has no real notch to key off, so its pin-assignments window reflects its current R flip on the desk — rotate it and the corners in the dialog swap to match.

Below the pin map, chips that have one show the manufacturer's datasheet crop — a cropped image of the connection diagram or function table pulled straight from the source datasheet PDF. If a chip has no crop on file, that part of the window simply isn't there — the pin map alone is still complete and accurate.

When Settings → Data Sheets points at a local folder containing that chip's full datasheet PDF, the window also grows a small document button in its top-right corner; clicking it opens the PDF itself in your system's PDF viewer. This is independent of the built-in datasheet crop — you may have one, both, or neither for any given chip.

Datasheets

The datasheet crops shown in the pin-assignments window are committed image assets built once from the manufacturer PDFs (make datasheets), not fetched or rendered at runtime — they work offline and load instantly. Four parts in the sequential/MSI wave have no matching 74LS* datasheet on file (74LS164, 74LS193, 74LS27, 74LS76) and simply show their pin map with no crop below it. Pointing Settings → Data Sheets at your own folder of manufacturer PDFs is a separate, optional feature — it doesn't add or replace the built-in crops, it just adds the "open datasheet PDF" button for any part whose PDF you have on hand.

See also Chips & Components for how chips seat into a breadboard, and Memory Chips & the Inspector for the memory group's file-backing and inspector.