SY85 & Gotek Floppy Emulator

01_Emulator_Contents

Introduction:

Every SY owner knows about the reliability of the in-built floppy drive, or will at some point. With the SY series knocking on 25 years the floppy drives can get a little unreliable. These drives use a belt to drive the disk spindle instead of the more modern direct-drive system. Over time these belts either stretch or can turn to a tacky mess around the spindles. The result is the Bad Disk error on the display with a useless whirring noise from the drive motor.

A popular fix is to fit one of the many types of floppy drive emulator. These interface with the synth using a cable adaptor and appear to the synth as a normal floppy drive. Getting data in and out of the synth is by using the usual Disk Load / Save menus. Most of these will use a standard USB Pen Drive to transfer data in and out of the emulator unit.

Different types of emulator have appeared in recent years. The first ones needed special software to write ‘disk images’ to the USB stick as single files. The emulator would see these images as a single disk and allow loading of the files stored in the image.

Recently this has got more user-friendly. One such emulator is the Gotek SFRM72-FU-DL. This type is a 720KB emulator and is designed to interface with systems that expect a 720KB floppy drive. They make a similar version that emulates a 1.44MB drive that can be interfaced to more recent synths that use a 1.44MB drive as standard. For the SY series we need the 720KB version.

Gotek SFRM72-FU-DL

This Gotek unit can operate using the older type disk-image file, or the friendlier folder-with-files option. To use the folder-with-files option you first format your USB stick in your PC to FAT16 or FAT 32 and then create numerical folders on the stick. These are in three figure names such as 001, 002, all the way up to 999. Each folder can have up to 720KB of files.

This Gotek drive has an inbuilt Memory IC that the SY reads and writes to. Any file Input or Output action using the synth is to and from this IC and not directly to the USB stick. The Memory IC is non-volatile so any files stored on it are preserved when the synth unit is powered off.

To get new files into the Memory IC you first tell the Gotek which numerical folder on the USB stick you wish to access. The stick must be removed before doing this. Using the front panel buttons you select a folder – let’s say 001. Once 001 is displayed on the LED segment display insert the USB stick. When the USB stick is inserted the buttons no longer select a folder number but now read or write to the folder on the USB stick. The button on the left will write the contents of the Memory IC to the Folder, and the button on the right reads the files from the folder and stores these into the Memory IC.

A slight annoyance is that you need to remove the USB stick if you wish to select a different folder. If you forget to remove it and try to select another folder with the buttons you will either load in files (right button), or overwrite the selected folder (left button).

The Gotek drive can access 999 folders. With the USB stick removed the right button increments the Singles, and the left button increments the Tens. To increment the Hundreds you press both buttons at the same time. Note that folder 000 is selectable. This is not a folder but actually the root directory on the USB stick.

If your folder contains many files that exceed the 720KB limit the Gotek will load in as many as it can until the 720KB limit is reached.

The drive itself comes supplied with fixing screws, spare jumpers, and a mini-CDROM with quirky Chinese software. If you plan to use the folder-with-files method then none of this software is needed.

The Firmware version of the unit can be checked by holding the two buttons in and powering on. The version this unit showed was “F21” & “129

There is a short User Manual (PDF) on the CD-ROM – SFRM72-FU-DL_UM.

Interface & Jumpers

02_Interface

The rear of the Gotek has a familiar layout. There’s the usual PC-type +5V & +12V Molex power connector on the left, and the 34 pin floppy interface on the right. The jumper configuration cluster sits behind the floppy interface. On the power connector only the +5V pin is used – the drive does not need the +12V supply.

The jumper configuration depends on your synth model and the type of adaptor you use. The adaptor I used was a version by Mike S Blunt that is detailed in this thread on the YamahaForums site. There are so many versions of adaptors on eBay and the like that I cannot say what jumper configuration will work with adaptor X. For the Mike S Blunt adaptor the only jumper I needed to fit was the S1 jumper.

Inside the Unit

03_Inside

Whenever I buy anything from China I always take a look inside. Some assemblies can be awful – not through bad design but rather build quality. Others are surprisingly good, like the Mini-Pro TL866.

The legs on the green LED have been squashed up against the metal housing on right side button, probably due to hasty assembly at the factory. Apart from that the unit appeared safe to use.

PCBAs Top Side

05_Pieces_Top

PCBAs Bottom Side

06_Pieces_Btm

Unit re-assembled and powered using an external hard drive PSU:

08_Unit_Powered

Note the two decimal-points on the display – “0 0.7.” These are shown when the USB stick is removed from the unit and the folder number can be changed. With the USB stick in place these will not be lit.

When the USB stick is installed and the left button is pressed (write to folder action) the display will show “d2” during the write operation. When the right button is pressed (read from folder action) the display will show “d0” during the read operation.

USB Stick Modification

09_Modified_USB_LED

Having the remove the USB stick each time to select a new folder became tedious after a time. This can be helped by adding a switch that temporarily disconnects the USB stick. There is a space on the front panel for a second LED so that was used as an indicator to the switch action.

10_Wiring_Close

The switch basically cuts the USB data trace at R1 to fool the unit into thinking the stick is no longer in place. The switch also lights the Bi-Colour LED according to switch position: Red for no USB stick, Green for USB stick present.

USB Stick ‘ON’

11_USB_ON

USB Stick ‘OFF’

12_USB_OFF

Back In Black

For the unit to match the SY85 a satin-black spray was applied:

13_Painted

And finally here it is installed in the SY85!

14_IN_SY

Using the Gotek to Load / Save Spanned Disk Sets

Normal Load & Save operations are fairly straightforward with the Gotek emulator. Remember that all the data you load & save data lives in the Memory IC until you save it out to the USB stick, or load new data in from the USB stick. You can even use the FORMAT menu in the SY85 to blank the Memory IC. A much quicker way to blank the memory IC is to create a folder on the stick – say folder 088 – and have no files stored in there. Just select 088 and load it in. All the files in the Memory IC will be gone – just like doing a FORMAT operation but much quicker.

Things get a little trickier when it comes to loading and saving a spanned disk set. It can be done but there is a sequence to remember!

Loading a disk set
As an example I will use the MEGA DX Set – this uses two floppies and requires the 2MB volatile SIMM memory upgrade.

There are two files the SY will need to load:
MEGA-DX.G01 (712KB) on the first disk
MEGA-DX.G01 (401KB) on the second disk

Both file names are exactly the same but the files are different sizes. We need to load the largest file first, then the second one. If we load the smaller file first the SY will complain.

Loading the MEGA DX Set uses the LOAD DISK ALL menu.

  1. Make Two folders on the USB Stick – 010 & 011
  2. Copy the largest MEGA-DX.G01 file to 010
  3. Copy the smaller MEGA-DX.G01 file to 011
  4. With the USB stick removed select 010 on the emulator and press the right button to load it in to the Memory IC – “do” will be displayed during the loading operation.
  5. Go in the SY’s Disk menu and select LOAD ALL. The MEGA-DX.G01 file will appear.
  6. Load the file – this will take a while.

When the SY asks for the second disk remove the USB stick, select 011, then replace the stick. Press the right button to load the file into the memory IC. Again “do” will be displayed during the loading operation.

When you press the Yes button on the SY it may say “ERROR – Insert Next Disk!“. This error will keep appearing even though you have loaded in the second disk into the Memory IC. What’s going on here..?

The SY is waiting for a signal from the emulator to say “a new disk has been inserted” but it hasn’t received this yet so it keeps asking for the second disk. The emulator actually does send this signal but only for a very short time (about 4 seconds) right after a file is loaded from the USB stick into the Memory IC – after the “do” disappears from the display. You need to press “Yes” within that 4 seconds or the next disk will never load!

After the second disk finishes loading from the emulator the whole MEGA DX set will be in memory!

Saving a Disk Set
Saving a disk also needs a certain sequence of events. Because the files are written to the Memory IC rather than a physical disk there is no obvious way to blank the Memory IC between disk swaps. You cannot jump into the FORMAT menu, or Rename / Delete menus between saving a spanned disk set. So what can we do..? Remember that blank folder 088 mentioned earlier – we load that into the Memory IC between disk swaps to create a blank disk for the next disk in the spanned set!

A cool thing the Gotek does is create a new folder on the USB drive if it doesn’t already exist. For example if you select folder number 055 and write the contents of the Memory IC to the stick the Gotek will create folder 055 and put the file there 🙂

Ok, to save a spanned set this is the sequence. We will save the spanned files to folder 020 & 021

  1. Remove the USB stick,  select 088, then put the stick back in.
  2. Load blank folder 088 into the Memory IC (right button), wait for “d0” to disappear.
  3. Go to the DISK SAVE ALL menu and SAVE using the original MEGA-DX name.
  4. The SY will save the first file to the Memory IC. It will ask you to insert the next disk.
  5. Remove the USB stick, select 020, replace the stick, press the left button to write the first file to the 020 folder – wait for “d2” to disappear.
  6. We need to blank the memory IC again for the second file. Remove the USB stick,  select 088, then put the stick back in. Load blank folder 088 into the Memory IC (right button), wait for “d0” to disappear. Remember to confirm “Yes” on the SY85 within the 4 second window!
  7. The second file will be written to the Memory IC.
  8. When this has finished remove the USB stick, select 021, replace the stick, press the left button to write the second file to the 021 folder – wait for “d2” to disappear.

Your saved spanned set will be in folders 020 & 021!

// END

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