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Internal or External?
Changing the RAM or the ROM inside the Z88 is a time consuming and skilled operation. Unless the user has good soldering experience, changing chips in a 25-30 year electronic device can lead to killing the Z88 altogether. Let's look at the advantages when a successful conversion has been achieved first.
Changing the 128K ROM to 512K Flash
OZ - the Z88's operating system has grown form 128K to 256K (with Rakewell's extra applications). Fitting the Flash chip internally gives an additional 256K of file area to save files into. This space is lost on standard Z88s.
Changing the 32K to 512K RAM
Just like the above, this reclaims the otherwise wasted unused space that the Z88 could use if there was RAM there. Surprisingly smaller RAM chips use more power than larger chips so if you want longer battery life, consider going for the 1M external RAM instead.
Use External Cards
Leaving the Z88 alone and using the external cards have quite unexpected advantages (apart from being a lot easier). The first thing the Z88 does when given a HARD RESET is to go to Slot 1 to see if there is a copy of OZ to run from there. If that happens, the program will not access the internal ROM thus putting in into standby mode.
External RAM (fitted in the card slot)
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 | 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 (fitted on the Motherboard)
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.
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