PAGE UPDATED 28.3.2010

A4000 IDE UNUSED PIN 20 REMOVAL FOR ROUNDED AND OTHER MODERN IDE CABLES

Many IDE cables have pin 20 blocked to guarantee that the cable can be connected only one way. Also many IDE devices have pin 20 missing, so they can use these IDE cables that have pin 20 blocked. However A4000 has pin 20 still on its place and so you cannot use many new IDE cables that have pin 20 blocked. In this guide I tell you why it is totally safe to remove pin 20 from A4000 motherboard.

Requirements:
Instructions:

A4000 IDE pins 20, 21, 28, 29, 32 and 34 are unused as you can see the schemastics below. So it is safe to remove pin 20. Leave other unused pins alone since cutting them all would just make connector less tight.


Before you start IDE connector in location CN900 should look like this.


Cut pin 20 marked here with blackyellow arrow with cutter or if you want just warm it with soldering iron and push and pull it away. For best visual result use desoldering tool.

In high resolution version of the above picture you may notice that there is a wider cap between pins 5-6 and 7-8. I think I am absolutely right when I say Commodore was saving in component costs and IDE 40 PIN header component was actually made of 2 separate parts. The first six pins are made of 2x3 PIN header that is very likely just a part of FLOPPY 34 PIN header component they have cut in many pieces and pins 7-40 are made of full lenght FLOPPY 34 PIN header. This allows any electonics manufacturer to have less storage costs when there is less different components. Ofcourse this is bad for end user since here for example some manual worker who cut those PIN headers did not do a good job and there is some extra plastic left in cut surface leading to misalign of the components.

List of unused ATA internal pins in A4000:
20 KEY Key
21 DMARQ DMA Request
28 SPSYNC:CSEL Spindle Sync or Cable Select
29 /DMACK DMA Acknowledge
32 /IOCS16 IO ChipSelect 16
34 PDIAG Passed Diagnostics

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