1M / 512K FLASH / 1M RAM PCB

Contents

Object

• the size of the card,
• the number of gold contacts,
• how many layers there are - a single layer is the cheapest but we want to aim for 2 layer.
• and how many are ordered at the same time.

When the Z88 was manufactured in 1988, a 32K EPROM chip (for example) took up half the space of the PCB and had big pins to solder. Chip sizes now are a lot smaller and use Surface-mount technology.

Why not make one multifuctional card that share the same size of card, same number of gold contacts, same number of layers? The numbers that are ordered can then be shared amongst the different types that the card can physically support.

It was decided that we could design a card to do FOUR functions. 1M Flash or 512K Flash or 1M RAM or 512K RAM / 512K Flash. with just FOUR chips.

Detail

Table

U1

U2

U3

U4

C1

C2 / 6

C3 /  7

C4 /  5

C8

LK1

LK2

D1

R1

1M RAM

1M FLASH

512K FLASH

512K RAM / 512K FLASH

Design Notes

Placing the components

The Z88 connector CN1 is fixed with power connections in the middle. Power distribution is like a tree. These are shown in RED. All the other signals (shown in GREEN) are to the left and right of this and would need to be shared by U1, U2 and U3. The 1M Flash chip U1 all the pins required go straight to the Z88 connector CN1. It is placed centrally towards the back, allowing half the signals to go through the other two main chips (U2 RAM and U3 512K Flash).

Writing data to flash chips the program first addresses certain fixed registers. This means that the address and data lines must go to the same pins - e.g. D1 to D1, D2 to D2, A1 to A1, A2 to A2 and so on. The RAM U2 just reads and writes, so it doesn't care where the physical address or data 'location' is. The data (shown in RED) and address lines (shown in GREEN) on the chip could be changed to line up with the data and address lines on the Z88 connector CN1.

The 512K Flash U3 lent itself to be placed on the right-hand side of the board as the chip pinouts are simular to the old style DIL chips. I originally ran the red tracks towards the outside of the board underneath the green tracks, thinking that the inside of the chip would be crowded, but this was not to be the case.

The Chip Select U4 was placed at the bottom left because A19 was that side of the Z88 Connector. On reflection it wouldn't have mattered which side it went on as A19 also goes to U1 1M Flash. This is why the LED was placed on the right-hand side (after this picture was taken). The links select either the 1M RAM or the 512K Flash when the 512K RAM / 512K Flash and the Chip Select U4 is not used.

Underneath the PCB the Configuration table was added. The decoupling capacitors were also placed here as well as on the component side. This was done just in case there was not enough room here for them. In the case of R1, if there is not enough space for it, it may have to be hard wired to the LED on the component side.

In v1, the configuration table was moved up to the unused connector area for clarity.

512K RAM / 512 Flash card Using the Test Points

Testing the chips individually. Build the 1M RAM card and test it. Remove the link (LK1) and deselect it, using the procedure described below. Build the 512K Flash card and test it. Remove both the link, wire and fit the Chip Select U4

This diagram shows the procedure used when deselecting either the 512K Flash (shown in GREEN) or the 1M RAM (shown in RED) after testing it.  (Note the position of Vcc has been changed in v1). A small length of wire is used to connect Vcc to the right hand side pad of the device that needs to be deselected.

1M Flash chip only

The LED (D1)  will come on when  is actively erasing or programming. (This includes programming in the Erase Suspend mode.) If the output is high (LED off), the flash chip is ready to read array data (including during the Erase Suspend mode), or is in the standby mode.

End Result Images below are of the Pre-production PCB

The PCB generated by the design program before the board is produced.

Photo of the 1M Flash card PCB with the components fitted.  The 1M Flash and LED, (not used on the current production to save battery power), with the decoupling capacitors.

Photo of the 512K RAM / 512K Flash card PCB with the components fitted. The 1M RAM, 512K Flash and the decode chip are fitted with the decoupling capacitors.

Post Production Errors

Mechanical

Electrical

The Vpp needs to be disconnected

The /CE needs to be connected to the 1M flash chip.

Version 1

• The Post Production errors have been corrected.
• The configuration table has been moved to the clear space on CN1.
• CN1 text moved to the centre of the connector.
• Link if RAM or 512K text made shorter.
  
• Rakewell's (c) & title of card moved to the other side.
• Capacitor pads have been increased in size.
  

Parts List & History

Farnell Parts List Now with pitch and size of chips

31/03/2009 Farnell will no longer be stocking the 512K, 1M or 4M Flash chips - Spansion are continuing to manufacture them so a new supplier may need to be found. There are sufficient quantities at the moment for our needs.

21/07/2009 Spansion are no longer manufacturing these chips - Rakewell buys up existing Farnell stock of 1M Flash.

13/11/2009 No more AMD 512K Flash chips from Farnel - considering AMIC - Programming change required.

01/12/2009 Rakewell locates part and buys up stock of AMD 512K Flash chips.

12/01/2010 Rakewell places order for the PCBs!

13/01/2010 Gunther points me to the places in the source code to add different Flash devices -

17/04/2010 Spansion manufactures 1M & 512K Flash chips (1M out of stock) AMIC Chips work.

04/12/2010 Low on stock of pre-production PCB. Work on Version 1 begins.

07/12/2010 Order placed for new batch of PCBs.

31/05/2013 Order placed for new batch of PCBs

10/07/2013 Problem with the Lyontek memory chip

Order
Code

Chip 
No.

Description

pdf data sheet

U1

AM29F080B-90ED 1Mx8 
FLASH 40-Pin 
Standard TSOP
0.5 mm pitch 10 x 20

http://
www.alldatasheet.com/
datasheet-pdf/pdf/178641/
AMD/AM29F080B-90ED.html

U1

AMD - 
AM29F080B-90SD. - 
FLASH MEMORY IC 

http://www.spansion.com/
Support/Datasheets/
21503g8.pdf

1488943

U2

BS62LV8001EIP55 - 
SRAM 8M, 1024KX8, 
2.4-5.5V, SMD

http://www.farnell.com/
datasheets/4486.pdf

2253667

U2

LYONTEK - 
LY62W10248ML-55LLI
 - SRAM, 8M, 1MX8, 
2.7-5.5V, 44TSOPII

http://www.farnell.com/
datasheets/1674434.pdf

1791222

U3

SPANSION - 
AM29F040B-70JF - 
MEMORY, FLASH, 
4M, 5V, 32PLCC

1791218

U3

SPANSION - 
AM29F040B-90JF - 
IC, MEMORY, FLASH, 
4M, 5V, 32PLCC

http://www.farnell.com/
datasheets/124800.pdf

1565992

U3

AMIC - 
A29040BL-70F - IC, 
SM, FLASH, 4MB, 5V 
Preferred

1085333

U4

74HC/HCT139 
Dual 2-to-4 line 
decoder/
demultiplexer

http://www.farnell.com/
datasheets/7590.pdf

1190107

C1

10uF Surface Mount 
Tantalum Capacitors 
1.6 x 3.2

http://www.farnell.com/
datasheets/18256.pdf

1288282

C2-8

0.1uF Case style:
0402 1 x 0.5

http://www.farnell.com/
datasheets/40863.pdf

1525564

D1

SLR-56VR3F — ROHM 
— LED,
 T13/4, 5MM, RED

http://www.farnell.com/
datasheets/5407.pdf

1108764RL

R1

PCF0402-R-220R-B-T1.
 — WELWYN — RESISTOR, 
220R 0402 25PPM

http://www.farnell.com/
datasheets/71882.pdf

8749493

 FLASH 5V 4MB, 
29F040, DIP32 

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