Z88 Extender Card

Owned by Vic Gerhardi
Last updated: Mar 15, 2017
7 min read

https://tinyurl.com/z753ho5

Introduction

This card was designed after an aborted attempt to build the same circuit using a 32K EPROM card board, ribbon cable and a ZIF socket. What many technicians have found is that it is difficult to connect wires to unused pins on the Z88 connector. The solder often runs along to the critical connecting area thereby ruining the card.


Connection to all the pins were made.

Low numbers were produced, but this item has now become popular again, due to the increase of technicians wanting to modify cards or the motherboard. It is a multifunction card that if produced again, would incorporate additional features.



Main description

The Z88 Extender card which has the gold edge connector for the Z88, is supplied as a 'bare board,' all other components to be ordered separately. It has the space to fit 

  • 2 x 34 way connectors which can be used to monitor the Z88 signals and connect to an external board,
  • 1 x 32 way DIL connector for a header to use with an EPROM programmer or a zero-insertion socket and
  • 1 x Z88 Card connector.

When the Extender card is used with a Z88, the 'Card Flap' needs to be modified, to allow the PCB to go through the flap.

Flash Chip Programmer

Fitting the plastic card case and a zero-insertion socket allows the Z88 to program chips up to 512K (like the Flash chip (AM29F040B)) with ROMcombiner, or ROMupdate.

This could be used to program the 512K Flash chip that can be used instead of the ROM in slot 0 of the Z88.

Up to 1M chips may be programmed by using an additional adapter card that fits into the DIL socket and using the additional signal A19, which is on a pad.

If this socket is used, the 2 x 34 way connectors cannot be fitted.

Note:

To allow the PCB to come out of the Z88, the card flap needs to be removed and a Pushbutton Switch, Off-(On), SPST-NO fitted in parallel instead

The Extender Card cannot be used to program EPROM because the Vpp signal (Pin 19 on the Z88) has been connected to Vcc.

Program Z88 Flash Card

Using a 32 way DIL and 8 way SIL header plugs, this card can be used with an external EPROM programmer (like the Dual Powered Willem Universal EPROM Programmer+27C256) or the W-USB programmer 1.5 EPROM programmer to program  Z88 EPROMs or Flash cards  up to 1M.

This allows developers designing software with the Emulator, to 'build' the image there and then download the file to the EPROM programmer to use on the Z88, saving time and complexity of saving the file first to the Z88 and then blowing the Flash or EPROM there.

Test Prototype board

The 2 x 34 way connectors used are the same ones used for the older type of IDE connectors to the hard disks. These connectors take all the signals from the Z88's bus to an external board where building and testing can take place. Plug in or transition connectors may be used depending on personal requirements.

Header plugs and sockets may be used to mount a daughter board on this card if desired.

This facility has not been used yet.

Test Z88 Card

Normally, it is impossible to test an external card when this card is in the Z88. By cutting another plastic card cover, to expose the PCB and leaving the connector end intact, probes may be used to see what is going on in real time.

This facility has not been used yet.

Use an ICE

As all the connections are paralleled out of the Z88, an "In Circuit Emulator" can be connected to the card with the DIL and SIL connector (like the NEW external W-USB programmer 1.5 EPROM programmer) or by using the 34 way cable connector. 

The Vcc 5v supply from the Z88 to the ICE should be disconnected. This can be achieved by breaking the connection in the connecting ribbon  cable.

This facility has not been used yet.

Components required

As this card can be used for different purposes, not all the components are required, nor can one card be built to use all the functions. Non-standard components are available from us, or faulty Z88 motherboards and memory cards may be canabilised to extract the Z88 card connectors and memory card cases. The standard components shown here are linked to the Farnell site. If you would prefer us to get these for you, we can and will add a 'handling fee' to cover our costs.


 


Function required

       

EPROM Programmer

       

Program Z88 Card

       

Testing Prototype Board

       

Testing Z88 Card

       

Using an ICE

       

Components required

       
Z88 Plastic Card Case
 Rakewell 
Z88 Modified Card Case
 Rakewell   
Z88 Modified Card Flap
 Rakewell

 
or remove and fit switch

163-4693


Z88 Card connector
 Rakewell  
HEADER, IDC, STRAIGHT, 34WAY
2
109-6992
   
CABLE ASSY, RIBBON 34WAY
 
101-2214
    
SOCKET, IC, ZIF, 32WAY
 
113-6782
    
PCB, EUROCARD, FR4, 2.54MM
0.25
117-2137
   
HEADER, STRAIGHT, 16WAY
4+2
124-8124
  
SOCKET, VERTICAL, 16WAY
4
341-9174
    
HEADER, RIGHT ANGLE, 0.1", 8WAY
1
588-775
    
HOUSING, 26AWG, 8WAY (A19)
2
109-8717
   
RIBBON CABLE, IDT, 8WAY (A19)
1
131-3461
   
SWITCH, 4POLE, 3 POS, PCB
1
112-3698
    
KNOB, 15.7MM, BLACK, YELLOW LINE
1
144-1137
    
WIRE, PTFE, A, GREEN, 1/0.4MM, 25M
1/25
118-4004
    

 

Circuit Diagram


Additional Features

If this card is produced again, the following points will be considered.

  • Vpp signal to be separated from Vcc

 

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