Microelectronics | IDC DATA CABLES

Synopsis

Once the ISA I/O Interface was completed, I decided to make some custom length data cables that will correctly fit the old InWin IW-Q500 full tower case and my other retro (unbranded) tower PC case.

I need the following cables.

One Floppy Disk Drive cable configured for 3½" 1.44 Mb (A:) and 5¼" 1.2 Mb (B:)
One Floppy Disk Drive cable configured for 3½" 1.44 Mb (A:) and 3½" 2.88 Mb (B:)
Four IDE Hard Disk Drive cables configured for either one 3½" drive or dual CF cards via adapter
One SCSI Internal Peripheral cable configured for four single-ended SCSI devices

For some reason I was always attracted by IDC ribbon cables. In my 1990s acception, these cables meant only one thing: high speed data highway. These days, however, serial data transmission cables are used for even faster data transfers than what can be achievable through parallel cables. In fact parallel data transmission technology appears to be obsolete already.

Disclaimer: This is an entirely hobby do-it-yourself project and I am not responsible for any damage made by any possible mistake. It requires very good assembly and debugging skills. In addition, I cannot offer any further technical support other than the contents of this article.

This project is in its final stage.

* * *

Laudatur ab his, culpatur ab illis. This project is provided as-is and is not for commercial purposes. It reflects my experimental work in microcomputer system design and should be treated as such. I release the plans to the public for educational purposes. I did all this at my own expense and in my free time. If you like my work, please consider making a donation. It helps me continue these kind of projects.

Bill of Materials (BOM)

The following list contains the parts that are required to assemble one floppy disk drive IDC data cable for connecting one 3½" and one 5¼" drive.

3½" AND 5¼" FLOPPY DISK DRIVE IDC DATA CABLE
Identifier	Value	Qty	Notes	Mouser Number
X1, X3	34-pin IDC Connector	2	2.54 mm Wire Housing Pitch	617-09185345813
X2.1	34-pin IDC Card Edge Connector	1	2.54 mm Wire Housing Pitch	517-3463-0001
X2.2	Card Edge Connector Accessory	1	Polarizing Key	517-3439-2
CABLE	34-conductor Flat Ribbon Cable	1	1.27 mm Conductor Spacing, 28 AWG	517-3365/34FT

The following list contains the parts that are required to assemble one floppy disk drive IDC data cable for connecting two 3½" drives.

DUAL 3½" FLOPPY DISK DRIVE IDC DATA CABLE
Identifier	Value	Qty	Notes	Mouser Number
X1-X3	34-pin IDC Connector	3	2.54 mm Wire Housing Pitch	617-09185345813
CABLE	34-conductor Flat Ribbon Cable	1	1.27 mm Conductor Spacing, 28 AWG	517-3365/34FT

The following list contains the parts that are required to assemble one hard disk drive IDC data cable for connecting one 3½" drive.

3½" HARD DISK DRIVE IDC DATA CABLE
Identifier	Value	Qty	Notes	Mouser Number
X1, X2	40-pin IDC Connector	2	2.54 mm Wire Housing Pitch	617-09185405813
CABLE	40-conductor Flat Ribbon Cable	1	1.27 mm Conductor Spacing, 28 AWG	517-3365/40FT

Construction and Pictures

The 34-pin IDC connectors have an additional plastic part called a strain relieve. I would've liked that the card edge connector (the one that connects to the 5.25"" floppy disk drive) was the same color as the 34-pin IDC ones.

Say hello to my little friend. We have a long history crimping IDC cables. So, we meet again!

This twist is mandatory as per floppy disk drive official documentation. Motor enable and control signals are inverted for first floppy disk drive. For the second one, the signals are not inverted.

This small plastic piece is called a polarizing key for standard card edge connectors. In case of the 34-pin 5¼" floppy disk drives, it needs to be mounted immediately after the second pin. Now the cable can only be inserted in one direction.

I have used Kapton tape on the IDC connectors so that my X-Acto knife glides easily without damaging the connector plastic material. The small sharp knife cuts the tiny wires and their insulation like butter.

This is the assembled 3½" and 5¼" floppy disk drive data cable. It looks way better than I imagined.

This is the assembled dual 3½" floppy disk drive data cable. This cable has inverted IDC connectors so that it can interface to the inverted connector Sony floppy disk drive units of the early 1990s.