The Apple I used to be an influential step in private computing historical past. Clones of it have grown in recognition since actual machines are uncommon (and costly.) As an alternative of making yet one more clone, retro-computer fanatic Chris Davis took a unique strategy. The Open AC-1 is a reimagined Apple I with a 6502 at its core with trendy microcontrollers supporting it.
The Open AC-1 circuit board accommodates RAM, ROM, a Peripheral Interface Adapter, glue logic, and several other microprocessors. A Western Design Middle (WDC) 65c02 runs the eight-bit Wozrom and BASIC code. Trendy interfaces can be found by way of a Microchip PIC32 and an Arduino Nano.
Open AC-1 (📷:Adwater & Stir, Tindie)
The PIC32 has two duties: USB keyboard enter and VGA video output. It communicates with an Arduino Nano. The Nano connects to the 65c02’s knowledge bus by way of an MCP23517 I/O Expander. The Arduino additionally offers an interface to an SD card.
Not like the unique Apple I, BASIC is accessible in ROM. Which suggests the pc is able to use after it boots. You may load BASIC applications from the SD card. The ROM additionally accommodates Wozmon, which is a monitor program. In older computer systems, the monitor means that you can view or change reminiscence contents. Some even allowed for assembling and dissembling quick applications.
Open AC-1 with VGA monitor and USB keyboard (📷: Adwater & Stir, Tindie)
In some methods, this package is harking back to the RetroShield. The undertaking used an actual 6502 (or Z80) processor linked to an Arduino Mega emulating classic computer systems’ logic. The Open AC-1, nevertheless, higher reassembles the unique Apple I with its handful of ICs cleanly laid out on a printed circuit board.
Total, the Open AC-1 does a unbelievable job of augmenting classic applied sciences with trendy parts. Davis designed the package solely with through-hole parts, which ought to make soldering extra accessible to these new to soldering.
Davis says the undertaking is totally open supply, though the GitHub repository (at present) lacks design information past a PDF of the schematic. Although you should purchase the Open AC-1 as an assembled package, the meeting and operations handbook does comprise vital documentation.
A completely assembled Open AC-1 is accessible for $129 earlier than delivery.