OZ V4.3 Release Notes

The first official release of OZ V4.3

3rd February 2012

It is with great pride that we present to you the first public release of the new OZ operating system for the Cambridge Z88. This release is a labor of love having taken more than 7 years by a dedicated team of three people.

VersionSizeAddedInstallation notesDownload Link

OZ V4.3 for Rakewell Flash Cards



Get Zip file, extract contents and upload to Z88. Instructions & utilities included in Zip file to blow ROM binary to an empty Flash Card in one of the externals slots of the Cambridge Z88

The Plan

Although attempts were made to get the original sources, they were on an obsolete non-working computer, so the only option was to disassemble, untangle, understand the v4.0 ROM and streamline the code. 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. Using the 1M Flash card there would be no need to do any hardware modifications on the Z88 at all and it also allowed OZ to break through the 128K space limitation..

Here are the changes and improvements from the users point of view:


The blank HELP pages allocated for each application were filled with useful information.


A new logo is displayed in the top right-hand corner showing which language is selected. (See Panel for further details).


has changes and additional functions

  • Slot 0 has been added
  • the ROM column has been changed to APPS
  • the EPROM column has been changed to FILES
  • the RAM column is unchanged. 
  • Additional FREE RAM information is shown. This is selected using the 0, 1, 2 or 3 number keys
  • the Free RAM banner displays how much RAM there is and how much is left.

 Here is the display after adding and selecting RAM.2.


  • A graphical page map of the RAM shows which area of RAM has been used...


Multiple Diaries can now be evoked.


The HELP menus have been restored from v3.00. They were removed to make space for the changes made to v4.00.


BBC BASIC has been updated to v3.10 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. 

An example showing the high-resolution (bit-mapped) graphics on the Z88's display.

This allows foreign versions to use this facility. It only worked previously from BASIC by loading and using a small 'patch' program which only worked with the UK versions, v2.2-3.0 and 4.0 and not with foreign language versions 3.12 to 3.26. 


No change.


No change.


No change, except from a later default start date.


No change.


Flash Cards are recognized and able to be used in any slot. EPROM commands changed to File Card. i.e.

  • Catalogue File Card
  • Save to File Card
  • Fetch from File Card

Create File Area in any slot command added.

View (File) added. This allows viewing the contents of a marked file.

When viewed it displays both ASCII codes on the left and the text on the right.


No change.


The "Press Enter to Update" banner has been added.

OZ now supports multiple keyboard layouts in the same ROM (see new selection item bottom right of the screen-shot). <>J will display available language layouts. Keyboard layout setting is remembered across soft reset.

Layouts yet to be done by volunteers: Icelandic, Italian, Swiss and Turkish.


No change


No change

New application to the operating system.


New application to the operating system.

Highlights of work done

We are in a new project hosting now, thanks to the kind support of Atlassian, donating a Community license to us, using Jira, Confluence and Bitbucket for our work. All the work that we did in those 7 years are recorded as change commits in our Git repository (which were migrated from the SVN repository at Sourceforge, which were originally migrated from CVS). Here, is a compressed list of highlights that we have done. For more details, we invite you to visit the our Git repository for the V4.3 release and see all changes made since 2003.

10/08/2008FilerOZ/Filer, OZ-11: Final implement of "Select File Card" command. Toggle selection now works and nice selection prompt is displayed.
19/08/2008FilerOZ/Filer, OZ-16: Fixed "Save to File Card" command, using new OS_EPR,A=EP_NewFile API. Existing files with same name in file area are automatically marked as deleted.
19/08/2008FilerOZ/Filer, OZ-16: Display "IN SLOT X" in the banner for all three File Card commands.
10/09/2008OZ/OZ/GN_Sip, OZ-18: Fixed <>S inverse casing for lower case ISO characters that has no upper case equivalent.
17/09/2008Filer/OZ, Filer popdown: Implemented OZ-23 ("Create File Card" command functionality)
18/09/2008Filer/OZ/apps/Filer, OZ-23: Implemented new "Create File Card" command. Also improved scanning of slots to recognize a flash card and default to that. Slot 0 now also selectable for file area (to be able to use special slot 0 file area bundled with OZ V4.2).
27/09/2008OZ/OZ/Filer, OZ-9: First work of new "View File" command implemented, based on Zprom's hex dump viewer.
02/12/2008OZOZ/Intuition integration: First (early) work of Intuition V1.2.dev version - this release recognizes OZ 4.2 API and is called through RST 08H instruction. For now, the existing OZ compile scripts automatically integrate Intuition as part of the OZ ROM, for development purposes. OZ ROM Release compile scripts will not contain Intuition. The runtime area is located in the OZ system variables; Intuition will be transparent for OZ. Further testing needs to be done to see if Intuition can trace OZ completely. OZ code that uses upper 8K of segment 0 will be re-written to reserve this segment for Intuition.
14/12/2008OZ/OZ/apps/Intuition: Integration in OS_In/Tin; activate Intuition when [] + INDEX keys are pressed.
28/12/2008OZ/OZ/Intuition: SQUARE + INDEX keys cannot allow to active Intuition itself, when it is already running.
16/02/2009OZ/OZ: New API in OS_Fep: FEP_RDFA, Reduce an existing File Area below Application/OZ Area. The code has been in OZ for a while but was not made public! Improved code by using the new OS_Ploz systen call to detect a running OZ.
16/02/2009OZ/OZ: New system call OS_Ploz, Poll for OZ card usage. Returns fz = 0, if slot contains running OZ. Will be used by Flash management sub-system to turn off screen when writing/erasing flash data on same card as running OZ.
14/07/2009Panel/OZ/apps/Panel: Re-positioned Keyboard selection to be at the end of the configuration selections, to be compatible with CLI scripts that iterate through the panel settings from the top. Suggestion from Vic Gerhardi of Rakewell.
15/07/2009Index/OZ, OS_Nq/NQ_Slt ($8903): Added functionality to recognize file areas on application cards. Index Card command now displays these as well.
15/07/2009Index/OZ/Index: Adjusted pixel algorithm for <>CARD command to display 128K rows properly. Still needs to implement a scaling when a card is less than 128K (typically 32K).
15/07/2009Index/OZ/Index: Graphics map now displays contents for 32K. However, OZ does not deliver a clean 64 pixel area; 16 bytes offset are not displayed at the beginning and for each 8 pixel row.
17/07/2009Index/IZ/Index: First work of Free Ram display in <>CARD command.
19/07/2009Index/OZ/Index: Implemented pixel algorithm for <>CARD command to display 32K rows properly (pixel scaling, eg. 128/32 = factor 4).
19/07/2009Index/OZ/Index: Forgot to remove lookup entry (that was never used by Free Ram anyway).
19/07/2009Index/OZ/Index: Free Ram display user interface integration completed. Now, user can select available RAM card and see free space.
20/07/2009IndexWrote a help page for <>CARD command that explains the command features.
20/07/2009Index/OZ/Index: Get the base address of Map area, just before clearing or drawing free memory map (because it might have changed if system changed from non-expanded to expanded machine).

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