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OZ 4.2/3 and the Flash Card

Introduction

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

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.

The v4.0 ROM

This was the last update made but never released by Cambridge Computer and sold in a 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. These screens have been restored in OZ 4.2/3.

 This version served as the starting point for OZ 4.2.

OZ 4.2

BBC BASIC v 3.1

BBC BASIC has been updated by Richard Russell. This allows you with an expanded machine (with at least 128 Kbytes of RAM), to draw graphics in a 256x64-pixel window using simple BASIC statements. It also provids a BASIC line editor. Commands provided are *EDIT, MODE, CLG, DRAW, MOVE, PLOT and POINT; their syntax is compatible with other versions of BBC BASIC. 

The high-resolution (bit-mapped) graphics now works with the Z88's display. This only worked previously from BASIC by loading and using a small 'patch' program. This only worked with the UK versions, v2.2-3.0 and 4.0 and not with foreign language versions 3.12 to 3.26.

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