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The Z88 Flash/RAM card has been working for several years now. When OZ 4.6 was introduced, allowing applications to be run in RAM, some games failed to run.

Standard VersionDecoder and PROM socketRAM VersionFLASH Version

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This was thought to be due to an intermittent timing error from the decode chip CD74HCT139 which switches between the RAM and Flash chip but after the Z88 Hardware Investigation, it has been discovered to be a misunderstanding by both the hardware and software engineers on how to write faultlessly to the flash chip. This has only affected a few users, i.e. those who play games in RAM or who do repetitive writing to the flash card. The majority of users have not reported any problems.

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Edge ConDecoderSignalOTP EPROM1M RAM1M Flash
301
SE1EXISTING CONNECTION
382
A19EXISTING CONNECTION
373
A18



714OTP CE22RH 512K LKRH 512K LK


11RAM CE
RH RAM LK


11FLASH CE

LH RAM LK

256K OTP EPROM 768 RAM Modifications follows

Step

PinPinPinPinPinInstructions








Reinstate POE/ROE mods
they are no longer needed.
1

U43451415Lift up pins
DO NOT CONNECT TO PCB
2

U4126-89-1316Solder chip to board
using the remaining pins
3a

U43



A18 - Connect wire
from U4 Pin 3
to (See step 3b)
3b

U1




to a via near 1 U1U1.
(Above the d in 'used'
and to the RH side of
the figure 1).

4

U47

14
Connect wire from
Pin 7, 14 to RH pad of 512K
5

U4


11

Connect to RH pad of RAM

NOTE: This is for the RAM.
It is the only difference
between the RAM
and FLASH card

6

U3




Fit socket for U3

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U3

Lift off Pin 1


Cut track (A18)

U31



Connect to Vpp
Edge connector Pin 19


LK1 - LK2





256K OTP EPROM 768 FLASH Modifications follow


Step

PinPinPinPinPinInstructions








Reinstate POE/ROE mods they are no longer needed.
1

U43451415Lift up pins DO NOT CONNECT TO PCB
2

U4126-89-1316Solder chip to board using the remaining pins
3a

U43



A18 - Connect wire
from U4 Pin 3
to (See step 3b)

3b

U1




to a via near 1 U1U1. (Above the d in 'used' and to the RH side of the figure 1).
4

U47

14
Connect to RH pad of 512K
5

U4


11
Connect to LH pad of RAM
6

LK1 - LK2




Cut track between LH pad of 512 and LH pad of RAM
7

U3




Fit socket for U3

Image Removed

U31Cut track (A18)

DO NOT connect Pin 1 (Bottom row middle pin) to the PCB. Lift off the pin to connect the wire at the next step.

8

U31



Connect wire from the lifted off Pin 1 U3, to Vpp Edge connector Pin 19

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