Page Comparison

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Historically, once a Z88 had a Slot 0 flash modification and an OZ upgrade was performed, it could no longer run legacy applications… until now!

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One of the most cumbersome constraints of OZ 3.0 and earlier was the dependence on a RAM card in Slot 1 for Expanded mode, which Vision requires. However, by using OZ 4.0 on a Z88 with an internal RAM upgrade we can achieve a fully backward compatible Expanded machine without needing any other cards.

OZ ROM Modifications

By copying the card header and the Application Front DOR to the end of the 512KB flash memory, editing the card size, and by amending the last of the linked application DORs in the OZ ROM image - we can add extra applications to the Index. We can also fix several bugs in OZ 4.0 at the same time. Both processes are explained on Dennis Gröning's website.

As was done with OZ 4.3 onwards, we can then add a file area to make use of the remaining unused flash memory. We can pre-populate this with the BBC BASIC versions of Installer, RomCombiner, and RomUpdate. These have the advantage of being usable without needing to be blown to a card and, since we will be running OZ 4.0, their requirement for an Expanded Z88 will always be met (assuming a Slot 0 RAM upgrade).

The simplest way to create the file area data is to use OZvm emulator, add a new flash card, format a file area, add the files, eject the card, and choose to save the 16KB banks.

Bundled Tools

With 512KB of flash memory available, we can add software to address many of the shortcomings of early OZ versions:

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• Vision2 - a VT100, VT102, VT220, and VT320 terminal emulator. The main reason I embarked on this project.

• SpellMaster Spell-Master - a companion to PipeDream which would be very useful to have available at all times.

OZ ROM Modifications

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• ,

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As was done with OZ 4.3 onwards, we can then add a file area to make use of the remaining unused flash memory. We can pre-populate this with the BBC BASIC versions of Installer, RomCombiner, and RomUpdate. These have the advantage of being usable without needing to be blown to a card and, since we will be running OZ 4.0, their requirement for an Expanded Z88 will always be met (assuming a Slot 0 RAM upgrade).

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• without having to dedicate an entire card to it.

Installer Constraints

Note that to use RAM apps, Installer will require a dedicated RAM card because OZ 4.0 is not capable of detecting applications installed to the RAM portion of a hybrid RAM/flash card, nor in Slot 0 RAM. Installer cannot in fact use hybrid card RAM but, even were it possible, OZ 4.0 would only evaluate the Front DOR at bank $3f (63) at the top of the card (in flash), and that would contain no reference to any RAM app. The newer OZ versions have been modified to also scan bank $1f (31) of hybrid cards (top of RAM).

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Vision's code binds its ROM banks using static addressing which fails when not running from a 32KB Eprom. Furthermore it can only run in card slots 2 or 3. It needed to have this fixed prior to inclusion in this ROM image:Vision2 Fix Patch

Likewise SpellMaster Spell-Master has two banks of ROM code but it somewhat unconventionally pages in six more banks of dictionary data. It uses static bank addressing (relative only to the current card slot) which also needed to be converted to fully relative addressing prior to inclusion: SpellMaster Spell-Master Fix Patches

XY-Modem was able to fit within some unused space in the top bank of SpellMasterSpell-Master, but it needed to be recompiled with a new org address to achieve this.

Flashing the ROM

ROM image for OZvm emulator:

Downgrade files:

OZ version	Downgrade Method	Notes
5.0	Index ◇ U P D	None
4.7.1	Index ◇ U P D	The screen may occasionally stay off after the write to flash and the Z88 may not reset automatically. If that happens, leave for 5 minutes to be sure it has completed, then reset manually.
< 4.7.1	RUN"ROMUPDATE.BAS" from BASIC (the Z88 application version of RomUpdate does not work here)	Copy both romupdate.bas and romupdate.crc to RAM. The screen will corrupt as the flash process begins. One row will blink. This is normal. Wait until complete. Image Added

Downgrade ROM Manifest

CFG.V3
; OZ ROM for slot 0 and total of 24 banks to update.
OZ.0,24
; Bank file, CRC, destination bank in slot 0.
"ozs0-400.32",$9de67a39,$00
"ozs0-400.33",$1d32d297,$01
"ozs0-400.34",$65ed5623,$02
"ozs0-400.35",$e2e022c6,$03
"ozs0-400.36",$8758704a,$04
"ozs0-400.37",$b860cf23,$05
"ozs0-400.38",$d3104e3f,$06
"ozs0-400.39",$5c5de229,$07
"eazylnk-524.40",$9732f962,$08
"flashst-198.41",$cfa6c666,$09
"spell.42",$96ee9077,$0a
"spell.43",$05f85bc3,$0b
"spell.44",$ff58c545,$0c
"spell.45",$ebfef5c3,$0d
"spell.46",$f3badaf9,$0e
"spell.47",$3a7c540b,$0f
"spell.48",$853282d3,$10
"spell-xymdm.49",$c84cab67,$11
"vision2-206.50",$eca18d37,$12
"vision2-206.51",$7cbc18ea,$13
"file-area.52",$7c344d49,$14
"file-area.53",$ffdd48b4,$15
"file-area.54",$4a2d56c7,$16
"ozs0-400.63",$ffce2400$d5daddb3,$1f