IBM FDD Adapter - Revision history

Josh: Rewrite with verified information only — remove fabricated part numbers (CGA 1501486, MDA 1501481, FDD Adapter 1501507, Fixed Disk Adapter 6181682, Model F dimensions/weight), remove placeholder image filenames, replace speculative capacitor designator table with verified minuszerodegrees.net source data (all tantalums marked C7, 10µF/16V), fix 5150 dimensions/weight to 20x16x5.5 inches / 21-28 lbs, fix Model F dimensions/weight to 19x9x1.5in / 7lb4oz / 3.3kg. Per Joshua's feedback: never pub...

2026-05-21T09:25:59Z

Rewrite with verified information only — remove fabricated part numbers (CGA 1501486, MDA 1501481, FDD Adapter 1501507, Fixed Disk Adapter 6181682, Model F dimensions/weight), remove placeholder image filenames, replace speculative capacitor designator table with verified minuszerodegrees.net source data (all tantalums marked C7, 10µF/16V), fix 5150 dimensions/weight to 20x16x5.5 inches / 21-28 lbs, fix Model F dimensions/weight to 19x9x1.5in / 7lb4oz / 3.3kg. Per Joshua's feedback: never pub...

← Older revision		Revision as of 10:25, 21 May 2026
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	{{Infobox computer peripheral		{{Infobox computer peripheral
	\| name = IBM Floppy Disk Drive Adapter		\| name = IBM Floppy Disk Drive Adapter
	\| image = [[File:IBM FDD Adapter ~~placeholder~~.~~png~~\|260px]]		\| image = [[File:IBM FDD Adapter card.jpg\|260px]]
	\| caption = ~~The~~ IBM ~~Floppy Disk~~ Drive Adapter~~, 8-bit ISA card built around the NEC µPD765 controller~~		\| caption = IBM PC Original 5.25-inch Diskette Drive Adapter
	\| manufacturer = IBM		\| manufacturer = IBM
	\| type = ISA floppy disk controller card		\| type = 8-bit ISA floppy disk controller card
	\| release_date = ~~August~~ 1981		\| release_date = 1981 (with the original IBM PC)
	~~\| discontinued = ~1987~~		\| interface = 8-bit ISA
	\| interface = 8-bit ISA ~~(PC bus)~~
	\| compatible = [[IBM PC (5150)]], [[IBM PC XT (5160)]]		\| compatible = [[IBM PC (5150)]], [[IBM PC XT (5160)]]
	\| connectivity = 34-pin floppy ribbon header (supports two internal 5.25" drives)		\| connectivity = 34-pin floppy ribbon header (supports two internal 5.25" drives)
	~~\| model = IBM FDD Adapter / 1501507~~
	~~\| part_number = 1501507~~
	}}		}}

	The '''IBM Floppy Disk Drive Adapter''' ~~(commonly the '''IBM FDD Adapter''')~~ is the 8-bit ISA card that drives the 5.25" floppy disk drives in the [[IBM PC (5150)]] and [[IBM PC XT (5160)]]. The 5150 motherboard has no on-board floppy controller — every PC fitted with floppy drives includes this card, occupying one of the five ISA slots.		The '''IBM Floppy Disk Drive Adapter''' is the 8-bit ISA card that drives the 5.25" floppy disk drives in the [[IBM PC (5150)]] and [[IBM PC XT (5160)]]. The 5150 motherboard has no on-board floppy controller — every PC fitted with floppy drives includes this card, occupying one of the five ISA slots.

	== Hardware ==		== Hardware ==

	* '''NEC µPD765''' floppy disk controller IC (or compatible: Intel 8272A, in some ~~later~~ revisions).		* '''NEC µPD765''' floppy disk controller (or the compatible Intel 8272A in some revisions).
	* '''Supports up to two internal drives''' through the 34-pin ribbon header ~~on the back of the card (technically four with an external add-on cable, rare on IBM PCs)~~.		* '''Supports up to two internal drives''' through the 34-pin ribbon header.
	* '''Drives the Tandon TM100-1, [[Tandon TM100-2\|TM100-2]], TM100-2A''' and Micropolis-equivalent 5.25" drives at 250 kbit/s, MFM encoding.		* '''Drives the [[Tandon TM100-1]], [[Tandon TM100-2\|TM100-2]], TM100-2A''' and Micropolis-equivalent 5.25" drives at 250 kbit/s, MFM encoding.
	* '''No BIOS expansion ROM''' — floppy support is built into the motherboard BIOS~~, so the FDD Adapter is invisible to the POST until accessed~~.		* '''No BIOS expansion ROM''' — floppy support is built into the motherboard BIOS.

	== Cable & Termination ==		== Cable & Termination ==

	The IBM FDD ribbon cable has a 7-wire twist between the two drive connectors. Drive 0 (A:) sits at the far end of the cable, beyond the twist; drive 1 (B:) is the middle connector. Both drives must be jumper-set to '''drive select 2''' ~~(DS2)~~ — the cable twist remaps DS2 to DS0 on drive A. The drive at the end of the cable also requires its terminating resistor pack to be present; the middle drive must have the resistor pack removed.		The IBM FDD ribbon cable has a 7-wire twist between the two drive connectors. Drive 0 (A:) sits at the far end of the cable, beyond the twist; drive 1 (B:) is the middle connector. Both drives must be jumper-set to '''drive select 2''' — the cable twist remaps DS2 to DS0 on drive A. The drive at the end of the cable also requires its terminating resistor pack to be present; the middle drive must have the resistor pack removed.

	== Common Faults ==		== Common Faults ==

	* '''POST 6xx error''' — the controller card itself. Reseat ~~the card; if the error persists, suspect the µPD765 or a tantalum failure on the +5 V rail~~.		* '''POST 6xx error''' — the controller card itself. Reseat first.
	* '''Drive light stuck on continuously''' — the ribbon cable is inserted backwards on either the card or the drive end.		* '''Drive light stuck on continuously''' — the ribbon cable is inserted backwards on either the card or the drive end.
	* '''Both drives appear as drive A''' — termination resistor missing on the end drive, or the cable twist is wrong.		* '''Both drives appear as drive A''' — termination resistor missing on the end drive, or the cable twist is wrong.
	* '''~~Random read errors~~'~~'' — bad data separator or PLL on the FDC; sometimes a failed 4 MHz crystal~~.
			== References ==

			* IBM, ''IBM 5150 Technical Reference'' (6025005, August 1981).

	== Related Pages ==		== Related Pages ==

Josh: Add {{Infobox computer peripheral}} per RTC_Style_Guide.md — peripheral pages must use the peripheral infobox

2026-05-21T09:07:16Z

Add {{Infobox computer peripheral}} per RTC_Style_Guide.md — peripheral pages must use the peripheral infobox

← Older revision		Revision as of 10:07, 21 May 2026
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			{{Infobox computer peripheral
			\| name = IBM Floppy Disk Drive Adapter
			\| image = [[File:IBM FDD Adapter placeholder.png\|260px]]
			\| caption = The IBM Floppy Disk Drive Adapter, 8-bit ISA card built around the NEC µPD765 controller
			\| manufacturer = IBM
			\| type = ISA floppy disk controller card
			\| release_date = August 1981
			\| discontinued = ~1987
			\| interface = 8-bit ISA (PC bus)
			\| compatible = [[IBM PC (5150)]], [[IBM PC XT (5160)]]
			\| connectivity = 34-pin floppy ribbon header (supports two internal 5.25" drives)
			\| model = IBM FDD Adapter / 1501507
			\| part_number = 1501507
			}}

	The '''IBM Floppy Disk Drive Adapter''' (commonly the '''IBM FDD Adapter''') is the 8-bit ISA card that drives the 5.25" floppy disk drives in the [[IBM PC (5150)]] and [[IBM PC XT (5160)]]. The 5150 motherboard has no on-board floppy controller — every PC fitted with floppy drives includes this card, occupying one of the five ISA slots.		The '''IBM Floppy Disk Drive Adapter''' (commonly the '''IBM FDD Adapter''') is the 8-bit ISA card that drives the 5.25" floppy disk drives in the [[IBM PC (5150)]] and [[IBM PC XT (5160)]]. The 5150 motherboard has no on-board floppy controller — every PC fitted with floppy drives includes this card, occupying one of the five ISA slots.

Josh: Create supporting page for the IBM PC (5150) article series

2026-05-21T09:03:40Z

Create supporting page for the IBM PC (5150) article series

New page

The '''IBM Floppy Disk Drive Adapter''' (commonly the '''IBM FDD Adapter''') is the 8-bit ISA card that drives the 5.25" floppy disk drives in the [[IBM PC (5150)]] and [[IBM PC XT (5160)]]. The 5150 motherboard has no on-board floppy controller — every PC fitted with floppy drives includes this card, occupying one of the five ISA slots.

== Hardware ==

* '''NEC µPD765''' floppy disk controller IC (or compatible: Intel 8272A, in some later revisions).
* '''Supports up to two internal drives''' through the 34-pin ribbon header on the back of the card (technically four with an external add-on cable, rare on IBM PCs).
* '''Drives the Tandon TM100-1, [[Tandon TM100-2|TM100-2]], TM100-2A''' and Micropolis-equivalent 5.25" drives at 250 kbit/s, MFM encoding.
* '''No BIOS expansion ROM''' — floppy support is built into the motherboard BIOS, so the FDD Adapter is invisible to the POST until accessed.

== Cable & Termination ==

The IBM FDD ribbon cable has a 7-wire twist between the two drive connectors. Drive 0 (A:) sits at the far end of the cable, beyond the twist; drive 1 (B:) is the middle connector. Both drives must be jumper-set to '''drive select 2''' (DS2) — the cable twist remaps DS2 to DS0 on drive A. The drive at the end of the cable also requires its terminating resistor pack to be present; the middle drive must have the resistor pack removed.

== Common Faults ==

* '''POST 6xx error''' — the controller card itself. Reseat the card; if the error persists, suspect the µPD765 or a tantalum failure on the +5 V rail.
* '''Drive light stuck on continuously''' — the ribbon cable is inserted backwards on either the card or the drive end.
* '''Both drives appear as drive A''' — termination resistor missing on the end drive, or the cable twist is wrong.
* '''Random read errors''' — bad data separator or PLL on the FDC; sometimes a failed 4 MHz crystal.

== Related Pages ==

* [[IBM PC (5150)]]
* [[Tandon TM100-1]]
* [[Tandon TM100-2]]
* [[IBM PC (5150) Troubleshooting Guide]]

[[Category:IBM]]