Amiga External Floppy Disk Drive adapter for 1.44MB PC FDD and Gotek FDD emulators.

This adapter helps you to connnect; 1.44MB PC Flopppy disk drives and GOTEK floppy disk drive emulators to your Amiga, externally.

Hello,

This is a tested and working circuit. This adapter has been tested on Commodore Amiga 500 with 1.44MB PC Floppy disk drives and GOTEK floppy disk drive emulators.

Amiga External Floppy Disk Drive adapter is an easy DIY project, all components are through hole and marked on the PCB, easy to solder, easy to make ;)

This adapter helps you to connnect; 1.44MB PC Flopppy disk drives and FlashFloppy* firmware installed GOTEK floppy disk drive emulators (SFR1M44-U100 or SFR1M44-U100K) to your Amiga, externally (from Amiga 23 pin disk drive connection). (Do not forget to setup the jumper position on the GOTEK, only S0 cap must be installed.)

*For information about FlashFloppy, you can look at the links below.

https://github.com/keirf/FlashFloppy/

Optional Hardware mods:

https://github.com/keirf/FlashFloppy/wiki/Hardware-Mods

Thanks to Keir Fraser for FlashFloppy project. https://github.com/keirf/FlashFloppy

PS: While using with Kickstart ROM V1.2 and V1.3 you may need AMIGA 500 - SWITCHLESS BOOT SELECTOR to boot from external drive.

PS. Most Floppy disks may deteriorate over time by losing their magnetic properties, so you may frequently see read-write errors. Unfortunately, this is normal and has nothing to do with the operation of this circuit.

When using 1.44MB 3.5" Floppy Disk Drives, the HD holes at the corners of High Density floppy disks need to be covered with a piece of tape (for using them as Double Density Disks.)

Jumper Settings:

J1  Short 1-2 (J1 pin1 and pin2 were shorted by adding a trace to the PCB.16/08/2024)

J2  Short 1-2 for 1.44MB PC FDD, Short 2-3 for GOTEK FDD emulator

J3  Short 1-2 for 1.44MB PC FDD, Short 2-3 for GOTEK FDD emulator

J4  Device number select (DF:1 DF:2 DF:3)

J5  Short J5 if 12Volts required (for some old model FDD)

(Translated from the original project page)

J1 - is responsible for the READY signal. If we connect an unmodified drive from a PC, the jumper should be set in position 1-2 (the READY signal will be generated based on the SELx and INDEX signals). Setting the jumper in position 2-3 will cause the READY signal to be read directly from pin 34 of the floppy drive (Amiga or modified from PC). Due to a design error, this jumper must always be set in position 1-2. (Fixed; J1 pin1 and pin2 were shorted by adding a trace to the PCB.16/08/2024)

J2 - is responsible for the DISK CHANGE signal. If we connect an unmodified drive from a PC, the jumper should be set in position 1-2 (the DISK CHANGE signal will be read directly from pin 34 of the drive). Setting the jumper in position 2-3 will cause the DISK CHANGE signal to be read directly from pin 2 of the floppy drive (Amiga or modified from PC).

J3 - is responsible for the SELx activation signal, which must reach the drive. Most floppy drives have a jumper to select the drive number (DS0 or DS1). Depending on the set drive number, the SELx signal must be applied to the appropriate drive pin. If the drive is set as DS1 (non-modified PC drives and drives without a jumper to select the number), jumper J3 must be set to position 1-2 (the SELx signal will go to pin 12 of the drive). If the drive is set as DS0 (Amiga or modified PC), jumper J3 must be set to position 2-3 (the SELx signal will go to pin 10 of the drive).

J4 - is used to select the floppy drive number, under which it will be visible in the Boot Menu and in the AmigaDOS/Workbench operating system. This number depends on the jumper position: 1-2 = DF1, 3-4 = DF2, 5-6 = DF3. Only in the case of Amiga CDTV is it different: 1-2 = DF0, 3-4 = DF1, 5-6 = DF2.

Many thanks to Roman Breński, Jarosław Bieliński and Radosław Kujawa for this project.

http://romanworkshop.blutu.pl/elec/amiextfdd.htm

http://romanworkshop.blutu.pl/

https://github.com/Sakura-IT/AmiExtFDD

https://web.archive.org/web/20180816232302/http://sakura-it.pl/floppy.php

Components:

3pcs. 2.2K ohm 1/4 watt resistance

2pcs. 100 nF ceramic capacitor

74LS74 DIP14

74LS38 (74LS00) DIP14   

2pcs. DIP 14 IC socket

DB23M D-Sub 23 pin male connector **

2x17 (34) pin, 2.54mm Pitch, Male, PCB type, straight, IDC box header connector.

3pcs. 3pin, 2.54mm Pitch, Male header.

4pcs. 2pin, 2.54mm Pitch, Male header.

4pin, 2.54mm Pitch, Male header. (for FDD Power)

5pcs. 2.54mm Pitch Jumper Cap.

34 pin (2x17) IDC Female to Female ribon cable (max 60cm) (Amiga FDD data cable)

4 pin 2.54mm Pitch Female to Female Header Dupond cable (max 60cm) (FDD Power cable)

This PCB

** There are several methods to obtain 23 pin D-sub male connector:

25 pin D-sub male connector's pins and the 3D model link below.

https://www.thingiverse.com/thing:1238286

Or you may chose this method.

https://archive.org/download/db23m/DB23M.jpg

Or you can buy online.

https://www.aliexpress.com/item/1005007020706331.html

Ps. While transfering data (reading or writing) from SD cards or USB flash storages it should not be interrupted like power-off or Reset systems. Otherwise that may damage memory chips.

In order to protect your electronical devices, always turn off your Amiga before connecting or disconnecting the cables or any other device.

Gerber files and component list are subject to change without notice. Before paying for the PCBs, be sure to update your orders!

As you can see I have uploaded many projects and I am still working on new projects. If you have any questions, please look for answers online. Unless I specify explicitly, all my projects are tested and confirmed to work under normal circumstances before being shared. I'm sorry I didn't have enough time to answer all the questions.

Use this PCB at your own risk !

Have fun

Thank you.

c64istanbul