What to do if you have a computer with a single floppy drive, but you want to have 2 floppy drives ora Gotek and a real floppy drive? Seems impossible, right? Well, now it is quite possible, thanks to the new project called DualSlim!
I've successfully modded my Arabic Al-Alamiah AX-350 to have a Gotek as drive A: and a real floppy drive as drive B:. Of course, those are not ordinary devices, they are so-called "slim" versions. The floppy drive is MPF820 and the Gotek is SFRM72-DU26 720K USB Floppy Drive Emulator.
The original floppy drive has the standard 34-pin flat ribbon cable, but those 2 devices have 26-pin FFP cable. How to connect those? After checking the design from one Japanese guy, I made my own version of the converter board. The files can be found here: https://github.com/RBSC/DualSlimAdapter
Will the FlashFloppy firmware work in the special slim Gotek? That answer was found on the FlashFloppy forum. After reading all replies, the following operations were identified to be performed in order to adapt the new slim Gotek for the DualSlim project:
- desolder JA, JB and JC
- remove jumpers JE and JD
- set jumper S1
- short 2 pins (boot) to enable programming mode
- connect Gotek to PC using USB-A-to-USB-A cable
- flash FlashFloppy 3.34 using the Artery software as described here: https://www.msx.org/forum/msx-talk/hardware/goteks-with-new-guts
Then I needed to merge 2 separate devices into one, so that I could install them into the AX-350 case. It was not a trivial task, I should tell as I am not an engineer. In the end, I've created the set of 3D models for the "merging" solution.
As a result, I've got a nice-looking and pretty sturdy "sandwich":
The 3D models of this "sandwich" set could be downloaded from my repository: https://www.thingiverse.com/thing:5445185
To fit the "sandwich" into the case, I had to level down the bottom metal plate FDD's mounting points using an anvil and a hammer borrowed from my wife. Also, you need to bend down the side holder:
So, the "sandwich" fits into the case now, but the drive B: doesn't work. Why? As there's no schematics for the AX-350 board and the YIS-805's schematics didn't help much, I had to remove the mainboard and see how floppy connectors were wired. It appeared that DS1 was not even connected on either FDD connector! The solution came quickly - connect DS0 from the external connector to DS1 of internal one. Bingo!
All seems to work now, so it's time to secure the "sandwich" inside the case. At first, I created the set of side holders that could be attached to the sides of the "sandwich" and fixed to the mounting points of the metal bracket. It was supposed to look like that:
But then it was decided to do this an easy way - to make 2 holes in the upper plate and secure the Gotek (and the entire "sandwich") with 2 screws. Now it's secure and won't budge:
The adapter board was isolated by tape at the bottom and was placed securely inside the AX-350's case. The keyboard fit without a problem and it even pushed the adapter a bit down, securing it even more. Now I have 2 drives instead of one in my AX-350! As my Gotek was white, I had to paint it to the best of my abilities (and I am a lousy painter). In the end it looks like that:
You can, technically, install an OLED screen into the slim Gotek, but it would be hardly visible in the current setup. So I skipped that part for now.
Please note that this project can be also used for modding other MSX computers with a single floppy drive to double the amount of drives in a system. Good luck!
P.S. I am going to apply FlashFloppy-OSD project into MSX world so that Goteks with side mounting could be used without looking at their own displays. Like here: https://www.youtube.com/watch?v=qwQa2THj6p0
