The Z88 has 32K of internal RAM. This is not enough memory for every day use.
The 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.
External RAM (fitted in the card slot)
The maximum size of RAM that can be fitted is 1M byte.
These became available about a year after the Z88 was released, but at £200 each, most users bought the 128K at just under £50.
Memory prices have fallen since then so this is more attractive now.
1M RAM
 | Rakewell will be selling their Flash/RAM PCB. This may be used instead of modifying the original 32K PCB board (see below). This would upgrade the card to 1M |
 | Amplia un cartucho de Z88 hasta 512Kbytes - Convert 32K RAM card to 512K RAM The memory chip described in the article above is no longer available. Suitable replacements are listed below.. |
  | CYPRESS SEMICONDUCTOR - CY62158ELL-45ZSXI - SRAM, 8MBIT, PARALLEL, 45NS, 44TSOP TESTED OK |
 | ALLIANCE MEMORY - AS6C8008-55ZIN - SRAM, 8MB, 2.7-5.5V, 1024KX8, TSOP44 TESTED FAILS |
| LYONTEK - LY62W10248ML-55LLI - SRAM, 8M, 1MX8, 2.7-5.5V, 44TSOPII This memory chip is a 'drop-in' replacement for the BSI chip (see below). TESTED FAILS when loading a file in PipeDream. |
| This memory chip has been used in the Rakewell's Flash/RAM card successfully. TESTED OK This part is no longer manufactured. BSI (BRILLIANCE SEMICONDUCTOR) - BS62LV8001EIP55 - IC, SRAM 8M, 1024KX8, 2.4-5.5V, SMD |
512K RAM
| Amplia un cartucho de Z88 hasta 512Kbytes - Convert 32K RAM card to 512K RAM The memory chip described in the article above is no longer available. Suitable replacements are listed below. |
 | ALLIANCE MEMORY - AS6C4008-55SIN - SRAM, 4MB, 2.7V-5.5V, 512KX8, SOP32 Note: This has not been tested. |
Internal RAM
The internal 32K of RAM is not large enough. Upgrading this to 128K or 512K internally is possible, but the original 'built-in' OZ operating system did not use this correctly.
Cambridge Computer commissioned OZ 4.0 ROM and were planning to use this with the new User Guide v3 but only the User Guide was changed. The new ROM was made available to users through the Z88 User Group.
The OZ version 4 ROM was the starting point for the disassembly of the code for subsequent versions of OZ. These are available in internal and external versions.
Z88 Motherboard
Here are where all the main parts are on the motherboard.
The external connector on the RH side was never used.
Note: On this motherboard the RAM socket is a 24 pin which is big enough for 32K. Later versions had a 28 pin fitted.
512K RAM
 | |
 | ALLIANCE MEMORY - AS6C4008-55PCN - SRAM, 4MB, 2.7V-5.5V, 512KX8, PDIP32 This has not been tested yet |
| |
| ALLIANCE MEMORY - AS6C4008-55SIN - SRAM, 4MB, 2.7V-5.5V, 512KX8, SOP32 This has not been tested yet
|
128K RAM
| ALLIANCE MEMORY - AS6C1008-55PCN - SRAM, 1MB, 2.7V-5.5V, 128KX8, PDIP32 This has not been tested yet |