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RAMs and EPROM cardsImage AddedZ88's operating system OZ is stored in a 128K ROM. It also has 32K of internal RAM (Slot 0). This is not enough memory for every day use

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The RAM memory can be increased two different ways.

  • Externally - by changing the RAM chip in an external card.
  • Internally - by changing the 32K RAM chip

Choosing a memory chip that works with the Z88 is important. Manufactures and the availability of chips change. See Memory Chips for the most 'up-to-date' results.

EPROMs and ROMs store OZ, the Z88's operating system and are used for permanent storage. These can be replaced with Flash

The Flash memory can be increased two different ways.

  • Externally - by changing the EPROM chip in an external card.
  • Internally - by changing the 32K ROM chip containing the operating system.

Articles on Modifying Motherboards

Before you start why not read these articles so that you can decide if it what you would like to do.

Z88 32K to 128K Upgrade

The memory chip described in the article above is no longer available.
Suitable replacements are listed below
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Motherboard Conversion in Service Manual

Z88 32kb to 512kb Memory Upgrade 

Original Article by Don Walterman

Z88 Motherboard Modifications - (This link has a Norton warning on it  )

The EPROM chip described in the article above is no longer available.

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Wide internally your Z88 to 512Kbytes

 

. External card slots increase the capability of the Z88 by adding RAM and EPROM cards, to increase the working area and save those important files. The maximum size (RAM or EPROM) that can be in the external card slot is 1M byte. Additional RAM was placed in Slot 1 to make the Z88 an expanded machine, additional  applications were stored in Slot 2 leaving Slot 3 free for saving files to EPROM cards. Increasing the ROM area, OZ has been able to grow, improved and new features added. This may be done in three different ways.

  • Modifying the motherboard and increasing the ROM and RAM size to the maximum value permitted, 512K ROM or Flash and 512K RAM.
  • Adding additional external cards
  • Adding additional memory to existing external cards.
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In 2010 the 1M Flash card was redesigned to use the physically smaller size chip size allowing three types of cards to be made each using the 1M maximum size permitted.

  • 1M Flash,
  • 1M RAM - (low power)
  • and 512K RAM/512K Flash cards.

The 512K/512K RAM/Flash card is the easiest way of expanding the Z88 with just one card. 256K of ROM, 512K of RAM and 256K of Flash file area to save those files before the batteries go flat.