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Thursday, 20-Jan-2022 13:05:03 GMT

Z88 Hardware

EPROM Erasers

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UpdatedUniversal Power Supplyavailable NOW

Key points

  • Input voltage 90-264 VAC
  • Input frequency 47-63 Hz
  • Overcurrent protection All outputs protected to short circuit condition
  • Operating temperature 0°C to +70°C, derate linearly above 40°C to 50% @ 70°C
  • MTBF 100,000 hours minimum at full load at 25°C ambient
  • EMI requirements Meets conduction limits of (a) FCC PART 15 CLASS B (b) CISPR CLASS B
  • Safety Approvals UL/cUL60950, TUV/GS (EN60950)
  • Size 91mm x 36mm x 38mm (3.6" x 1.4" x 1.5")


At last a small lightweight power supply for your Z88.

The Z88 does not physically switch to the power supply when being powered externally. Power from the internal batteries will only be saved if this power supply is used.The reason behind this is the Z88 runs on 6v, ( 4 x AA 1.5v batteries). A diode is used in the external supply circuit which drops the voltage by 0.8v. If the normal 6.5v Z88 Mains adapter is used for example, the voltage across the batteries will be

6.5 – 0.8 = 5.8v.

The batteries in the Z88 will be discharging until they reach 5.8v. This is about half their charge. The Universal Power Supply has an output voltage of 7v. This gives 6.2v across the batteries which ensures that they hold their charge.

When the Z88 came out the Mains adapters were built using large and heavy transformers, forcing users to either leave them at home or having two supplies, one for home and the other at work. This power supply is the modern lightweight equivalent .

Use it either in the USA, Europe or anywhere in the world.

Power on indicator


Stable Supply


Light weight


Fit the Plug yourself

showing the green LED indicator   plugged into the Z88   a feather   showing the two terninated end of the mains lead
See if it is plugged in   7v input ensures that your batteries are not used.  

weighs only 250g (9oz)

  Use it anywhere in the world.
Side view showing power supply with Z88

Note: LOW STOCK - will be discontinued

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Z88 Mains Adapter[Mains Adapter image]

  Save your batteries whilst working at home with this 220v 2 - pin mains adapter.

The 2 pin Euro plug can be cut off allowing an ordinary 13A UK (or any other) plug to be fitted if desired.

Weight 550g

Z88 MAINS ADAPTOR Plate Input 240v AC 50Hz Output 6.5v DC 500mAIf you want to use a different power supply it must be regulated and have an output of 6.8v to 7.2v with the positive pin being in the middle.

If you don't want to open it and you have a spare earphone, put that across the power output. If it buzzes like mad, it is unregulated, if you can't hear much of a sound it is either not connected, or it is regulated.

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Ram Packs

Using Ram Packs with your Z88.

[ image: Z88 with RAM pack]

Inserting the RAM pack into Slot 1 of the Z88

The Z88 comes with 32K RAM 'built-in' memory. This is used both as working memory and for storing files.


The Z88's memory can be expanded in 32K, 128K or 1M byte blocks by inserting a RAM Pack.

A 1M RAM Pack has enough room for around 200 typed A4 pages.

If power is lost, through the batteries going flat or if an application crashes, any files that or stored in RAM or unsaved current work may be lost.
Cambridge Computer The Z88 Card Exchange System (864K)

Cambridge Computer Memory Card booklet (500K)
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1M Low Power RAM Card

This uses a modern static RAM chip which gives the following advantages:-

  • 1M RAM
  • Low Power
  • Longer battery life.
This is a RAM pack.
If removed, a HARD reset is required

1M Low Power RAM card

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EPROM Erasers

EPROM Erasers

New style EPROM Eraser. The picture shows an EPROM Eraser with a EPROM pack just in the slot.
The Z88 is only able to write or read to or from an EPROM pack. When you save the same file twice, the Z88 only marks the old file as being deleted, it does not reclaim the space back. The EPROM Eraser allows you to clear the EPROM, to remove all the files, so that it can be used again.

The EPROM pack has a hole to expose the window on the EPROM device inside the pack to allow the light from the eraser to erase the EPROM. The EPROM pack is pushed right into the eraser to turn on the light and erase the pack.


EPROM Erasers formats EPROMs allowing them to be used again. Unlike disks, individual files cannot be erased.

Mains operated (240v AC) it has a 20 minute timer to erase the EPROM pack whatever the size.

We have reduced the price of this item due to the arrival of the Flash EPROM!

You can use this to erase ordinary EPROMs provided you make a carrier 2" wide to place the EPROM into the eraser instead of using an EPROM pack.

The bulbs for the old and new style EPROM Erasers are no longer available, but then at these prices - who cares?

Cambridge Computer EPROM Eraser Instructions (946K)

 Additional Information

Capacity 27xx EPROMs 24-28 pin
UV Intensity: Unknown
Board area: 50mm x 50mm 2" x 2"
Timer: 20 min.
Indicators: LED
Weight 160g
Dimensions 57h x 87w x 83d mm
Power 230 v No mains plug fitted
UV Tube Not replaceable - uses special UV QUARTZ bulb
Timer Board
ELREMCO 406/003
Chip used
MC14060BCP 14-Bit Binary Counter and Oscillator

Is there any other way to erase an EPROM ?

The following suggestions have been made.

  • I usually leave mine on the window sill for a while (to let the sun do its work). This can take some time in the winter, but get a few high UV days this time of year and you're laughing.
  • What about a tanning lamp, or one of those children's spy pens (writes invisibly until you illuminate with a UV source in the end of the pen - can be bought for £1!).
  • I tried that once and found that the lamp also melted the EPROM case. When I finally got the EPROM out I discovered that the files had not been erased at all.
  • There is a particular frequency in the UV spectrum that erases the EPROM. - Yep, you need a high-
    intensity UV source of wavelength 253.7nm. There's a DIY project I keep on meaning to try.
  • It uses a germicidal uv fluorescent tube, which (as you might have guessed) is not something you want to expose yourself to!
  • A lot of modern filters in garden ponds use these tubes, so if you have a friend who has fish try popping the EPROM inside the filter enclosure for a bit :-)
  • The tanning lamp I used certainly wasn’t on the right frequency but it did get me ‘browned off.’
  • When the Z88 User Club was running they offered a service to erase EPROM for £5 each.
    We can offer that service if you want but in the long run it doesn’t help and here is the reason why.

Z88 User

  • Umm – I’ve got a lot of files on my Z88, I should really back them up onto my EPROM just in case the Z88 looses them.
  • I’ve got a 128K EPROM pack; I could put them on there.
  • I don’t really want to fill it up because I haven’t got an EPROM eraser.
  • Oh bother – my Z88 has just crashed – I’ve lost all my files.

So the moral of the story is
If you want to use the EPROM packs please invest in the EPROM eraser, otherwise you will not use the EPROM and the benefit you would have will not be realised. The only exception to this is if you are using the EPROM to store Applications, then having an EPROM eraser is not so critical.

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Z88 Hardware
Description Price VAT Total
Cable - Printer (Parallel) £34.00 £6.80 £40.80
Cable - Printer (Serial) £5.00 £1.00 £6.00
NewCard Case
NewCard Case (machine screws and nuts only (4 or 2)
Carrying case £6.95 £1.39 £8.34
Flash EPROM (1M) £45.83 £9.17 £55.00

NewFlash EPROM (1M) LED Upgrade




Flash EPROM (512K) / 512K RAM

£49.17 £9.83 £59.00
EPROM Card (32K)
EPROM Card (128K) £25.00 £5.00 £30.00
EPROM Card (256K) £49.17 £9.83 £59.00
Keyboard Membrane
Mains Adapter (220v) £8.95 £1.79 £10.74
Modem 300/1200-software & cable £25.00 £5.00 £30.00
Modem £10.00 £2.00 £12.00
Power Supply (90-264v)
Note: LOW STOCK - will be discontinued
£30.00 £6.00 £36.00
RAM pack (1M) (low power)
RAM pack (1M) (CC)
£40.83 £8.17 £49.00
RAM pack (512K) £37.50 £7.50 £45.00
RAM pack (128K) £20.83 £4.17 £25.00
Topper - Heavy Duty Version Out of Stock

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