HardLabs

Apple ii rom adapter

erikarn·apple-ii-pcbs·apple-ii-rom-adapter/apple-ii-rom-adapter.kicad_pcb

Apple ii rom adapter PCB layout, top view — open source board by erikarn

About the Apple ii rom adapter PCB

Apple ii rom adapter is an open source PCB design by erikarn, published on GitHub. It is a 2-layer board measuring 53.6 × 45.2 mm, with 11 components from 9 distinct parts.

Other key parts include the 28C256, 74LS20, 74LS138 and 74LS02. By type, the board carries 4 ICs, 3 connectors, 3 capacitors and 1 resistor.

From the project

This is a simple project to replace all the ROMS in an Apple-II with a single EEPROM that holds enough to store both the applesoft and integer BASIC ROM sets.

This is a simple project to replace all the ROMS in an Apple-II with a single EEPROM that holds enough to store both the applesoft and integer BASIC ROM sets.

Yes, there are plenty of other solutions out there. I built this because I wanted to learn more about KiCAD and PCB layout.

It plugs into the D0 ROM and 74LS138 IC that does IO and ROM space decoding. It uses an 28C256 32 kilobyte 8 bit parallel EEPROM for storage, which stores 2 x 12 kilobyte ROM images. It uses a 74LS20 (dual 4-input NAND gate) and 74LS02 (NOR gate) to decode the 74LS138 output enable pins to enable the ROM. And it…

Main components on the Apple ii rom adapter

28C25674LS2074LS13874LS02

Apple ii rom adapter bill of materials (BOM)

11 components, 9 distinct parts.

QtyPartRefs
1
28C256
U1
1
74LS20
U2
1
74LS138
U3
1
74LS02
U4
1
ROMSEL
J1
1
9316 insert
J2
1
74LS138 insert
J3
3
0.1uF
C2, C3, C4
1
1k
R1

Apple ii rom adapter design files

The KiCad project lives in the erikarn/apple-ii-pcbs repository on GitHub; these links point at the commit this page was built from.

Apple ii rom adapter: common questions

How big is the Apple ii rom adapter PCB?

The Apple ii rom adapter measures 53.6 × 45.2 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Apple ii rom adapter?

11 components, from 9 distinct parts. The full bill of materials is listed on this page.

Where can I download the Apple ii rom adapter design files?

From the erikarn/apple-ii-pcbs repository on GitHub, which has the KiCad layout; the links under Design files point to each one.

Can I use the Apple ii rom adapter design in my own project?

The repository has no license, so all rights stay with erikarn. Use it as a reference, and ask the author before reusing the design.

More boards in apple-ii-pcbs