A-ONE replica

I have a A-one extended. Beautiful system, well designed and build. A-ONE hardware design: Franz Achatz , Video controller Software: San Bergmans, Keyboard controller Software: Ben Zijlstra

SB-Projects, San Bergmans’ description of the working of the Apple 1 and all about the A-ONE

The A-ONE is a compact and high quality Apple 1 replica made and designed in the Netherlands by Achatz Electronics. Similar, but not identical to the Apple 1 Replica 1. Advantages are the small board size and low IC count,, 50 Hz and 60 Hz rock solid video, and the real Apple 1 slot.


  • System-Clock: 1 MHz
  • RAM Memory: 32KB SRAM
  • ROM Memory: 32KB (64KB EPROM, selectable are two banks)
  • Video: 40 Chars/line at 24 Video-lines 50Hz and 60Hz
  • Video Out: Composite positive Video, 75 Ohms
  • Keyboard: PS/1 Keyboard interface
  • RS232: 9-pin SubD Female, 2400 Bd
  • Expansion: 2×22 Edge Connector
  • Powersupply: recommended is single universal AC-DC Adapter
  • Voltage: DC 9-12VDC
  • Supply Current: 250 mA
  • PCB Size: 160 x 100mm

A-ONE Extended

The A-ONE Extended is a standard A-ONE with additional a large breadboard and three Apple 1 slots. Together with the breadboard prototype board this make it quite an impressive system to develop hardware for 6502 systems!


A-one extended

A-one extended

A-ONE manual 1.10
A-ONE manual 1.10
Elektuur announcement
A-ONE flyer
A-ONE terminal description by San Bergmans
JP1: Video 50/60Hz
JP2: MemoryMap (see Manual)
JP3: H-A14 = 65C02 CPU
     A14-L = 6502 CPU


A-ONE extensions

Since the Apple 1 slot is standard, it must be possible to use the Apple 1 and Replica 1 extensions, such as the CFFA1 and the multi-I/O board on the A-ONE. It will need a A-One slot to Apple 1 slot onnection, perhaps via one of the prototype boards.

Working with the A-ONE extended becomes even more a pleasure with the prototype boards sold by Achatz Electronics.



A-ONE information

The design of the A-ONE is well documented and open: see the excellent website of San Bergmans

Photos of my A-ONE Extended

Photos of the development