J.E.Lawrie                                                           HINTS-26.


OZ4 Operating Chip.

  Before production of the Z88 was stopped it had been intended that  the  OZ3
  chip would be replaced by an OZ4.  This probably never happened but the chip
  was made available through the Z88 Users' Club (now defunct) at about £25.

  The chip could only be fitted in place of the OZ3 if that was plugged in  to
  a  32-pin  socket,  not  a 28-pin, unless one was very brave and very expert
  in soldering a 32-pin chip on to a printed circuit board !

  Everyone I have spoken to, who has tried the OZ4, has been very  happy  with
  it.   I  have  tried FOUR, two on each of two Z88s and I got more trouble in
  two days than I had had in two years so I'm not a great believer.

  This is what the OZ4 does -

    Prevents "in use" errors in the Filer

    It is possible with the OZ3 to insert and remove ROMs with the machine off
    - this is not good.  Now it wakes the machine as the card slot is opened.

    Updating the PrinterEd will not cause a FAIL.

    There  is a third page to the PrinterEd which gives a further twenty-eight
    translations.  Since even the nine on page two is four too many for normal
    use on British machines this ain't much of an improvement.

    Files left in RAM.- will not cause any problems.

    A machine is "expanded" no matter where a RAM larger than 32k is  located.
    On  previous  versions of the machine a larger RAM on the main PCB did not
    make it "expanded" - a minimum 128k in slot 1 was still required.

  Ah!  how  does one know which version of the Z88 they have?  Go to INDEX and
     press the HELP key, then the left arrow key and look at the top line.


Faulty Cartridges

  We have probably all seen the two covers of RAMs and  EPROMs  coming  apart,
  especially  the  latter  as  they  get  more handling.  One may think that a
  little  looseness  here is of no consequence but it can prevent good contact
  between the strips on the cartridge and the wire connecters inside the slot.

  In  the case of an EPROM ( I've never had trouble with a RAM ) it might well
  be the cause of it failing to be recognised or failing to accept  files  and
  causing  an  error  message.   So you could go on repeating erasures without
  ever getting acceptance and yet it has been successfully erased.

  So, if you get a loose case on a cartridge, glue it.  Doesn't take more than
  a  tiny bit in each corner but it doesn't matter if it can't be opened again
  as there's little chance of finding/repairing a fault if there really is one



                                                                           END

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