Pages of Understanding the Apple II - Ch. 6 -ROM in the Apple II

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• page 6-1
  • ROM hardware
• page 6-2
• page 6-3
  • schematic: ROM in the apple ii
• page 6-4
  • firmware in the apple
  • the seventh ROM chip
• page 6-5
  • the monitor ROM
• page 6-6
  • ROM timing
  • the apple ii plus
  • the impact of the RAM card
• page 6-7
  • timing example: ROM read, address $F000
• page 6-8
  • enabling the firmware card
  • the firmware peripheral card
• page 6-9
  • schematic: the firmware card
• page 6-10
  • the DMA priority chain
  • the ROM ENABLE signals
• page 6-11
  • firmware card jumpers
  • firmware card timing
• page 6-12
  • timing example: a read from address $F000, firmware card enabled
• page 6-13
  • EPROM in the apple
• page 6-14
• page 6-15
  • construction of a socket adaptor, EPROM to ROM
• page 6-16
  • modifying the system monitor
• page 6-17
• page 6-18
  • modifying the firmware card for independent selection of the F8 ROM
• page 6-19
  • added switch to control the F8 ROM on the firmware card
  • circuit syncronizes switching to prevent possible program crashing
• page 6-20
  • circuit to allow independent selection of the F8 ROM
• page 6-21
  • method for isolating the F8 chip selects from other ROM chip selects
• page 6-22