Welcome!
Here's the version number screen for OZ v4.3 the Z88's latest operating system:
History
Just to give ourselves a reality check in 1987 when the Z88 was conceived, the operating system that ran on the Z80 processor was CP/M and the popular Word processor was WordStar.Cambridge Computer (CC) decided to start from scratch as both these programs had licencing implications, yes, you guessed it, they would have to pay the fees on each Z88 sold. Using the philosophy of work hard now, jam tomorrow, three individulas were chosen for the tasks.
Being a battery powered device, what was needed was a dOZy operating system, one that could go to sleep rather than have to be shutdown and then rebooted when required again. It was an ambitious undertaking. With only 128K of space to fit all the applications and help pages, this only happened eventually using a larger device.
A number of different ROMs were produced by CC (See listing at Dennis Gröning's website for further details). These include foreign versions, supporting a subset of the ISO LATIN character set for each country-specific release. The size of the ROM was 128K.
OZ v4.0 ROM
This was the last update made but never released by Cambridge Computer and sold in a Z88. It was made available through the Z88's Users Club and replaced the ROM inside the Z88. The following software 'bugs' from the previous versions were fixed.
- ROM Cards - The Z88 got confused if cards were inserted or removed cards while it was switched off. The Z88 now wakes up when the card flap is opened.
- PrinterED - When updating, it was common to encounter a "FAIL" condition. The "Allow line feeds" option now works correctly.
- RAM.- - The Z88 got confused if files were present when it was reset.
- Expanded Z88 - Adding an additional 128k RAM anywhere in the system (instead of just in Slot 1) now works (giving a full map in PipeDream, and 40K workspace in BASIC).
- Help Screens - Initially most of them had to be removed to gain space for these changes to be done within the 128K EPROM space. These screens have been restored in OZ 4.2/3.
The future of OZ, developed by the community
The V4.0 version served as the starting point, done by a full reverse-engineering of the V4.0 ROM binary into auto-generated source code. This work took more than 4 months, and became the continuous development work into OZ V4.1 and V4.2 internal releases, done by the team - ultimately reaching V4.3 in June 2012 as the first public release.
Flash Cards for the Z88 - a better card technology than EPROM's
It has been a long journey from making the first Flash card and updating the OZ software. One could not have happened without the other, so in this section we will cover the historical aspect of the hardware developments as well as what are the advantages of using the latest software.
Initially, the Flash card was just going to replace the EPROM card. A BBC BASIC program was used to FORMAT, Save and Fetch the files. Just having these functions without listing files that were stored on the Flash card quickly required the software to be written as an application.
In parallel with this, users were updating their Z88 with OZ v4.0. It was available via Z88 Users Club. To use it, the motherboard needed to be removed
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Hardware wiring modifications were then needed to replace the existing ROM on the left and expand the internal memory (32K) on the right.
It was known that there was a 'software hook' in OZ that would allow the Z88 to boot into software written in the external slot 1. The 1M Flash card was the ideal candidate for this, there would be no need to do any hardware modifications on the Z88 at all. Before this could happen, OZ 4.0 needed to be disassebled, re-organised documented and understood.
During this discovery stage it was found that RAM and Flash could be on one device, hence the 512K/512K Flash/RAM card was developed.
This allows users to add
- a new operating system
- increase the RAM
- and have an area for storing files
all in one device externally.
None of this would have happened without the support of all the people, past and present, who have been involved in this project. They know who they are, thank you for all your efforts.
This space is under construction - check regularly for updates..
