Apple ][ Technical Details and Trivia



  • a mains power socket - 3-pin "kettle" lead style, male.
  • a Cassette port in (for loading) and a Cassette port out (for saving) - 3.5mm jack sockets.
  • a Game port - 9-pin DSUB.
  • Composite video out - RCA phono, female


Technical Facts

Apple ][

  • The Apple ][ came with 4 KB RAM, expandable to maximum of 12 KB if using 4 KB RAM chips, or 48 KB if using 16 KB RAM chips.
  • The first 4 KB of memory is used by the 6502 processor, ROM routines and text screen display - it's mandatory this is fitted.
  • The motherboard has two empty ROM sockets for the end-user to install their own ROM chips. Apple sold a number of their own ROM chips containing certain software, including the "Programmer's Aid #1". This contained various utilities for Integer BASIC programmers including machine code routines that could renumber BASIC programs, merge two programs together, relocate assembly language routines to a different memory location, test the RAM, create musical tones and handle hi-res graphics in BASIC.

Apple IIe

  • The IIe came with 64 KB as standard - the maximum the 6502 CPU could address. It can handle both 4K and 16K RAM chips.
  • There is a built-in self test program which can be run either by starting the computer with the Closed Apple and Open Apple buttons held down, or by holding down Closed Apple, Ctrl and hitting Reset. The test also starts automatically if no keyboard is detected on power-up. It tests the main RAM and auxiliary RAM, MMU (Memory Management Unit), IOU (Input/Output Unit), and GLU. If all tests pass the message "SYSTEM OK" (for Enhanced IIe), or "KERNEL OK" (for standard IIe) is displayed.

Apple IIc



Hover your mouse over the circuit board for a description of the components




  • The Apple ]['s RF modulator that was designed in-house gave off far too much interference to pass FCC regulations. Instead of waiting for a redesign, Apple decided to outsource the job to M&R Electronics, having given them the specifications to the in-house RF modulator. M&R Electronics would be allowed to make and sell the RF modulator while Apple could focus on selling the computer without a modulator. The "Sup’R’Mod" sold in huge numbers!
  • Steve Wozniak created the Integer BASIC for the first Apple ][s in pure machine code on paper - he never created an assembly language file for compilation! When it came time to put it into the computer, he coded each opcode/operand manually.

Apple ][ Board Revisions


Apple IIc Board Revisions


Apple IIe Board Revisions



This page was last updated on 15th March 2018.