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Modify a GOTEK floppy emulator

Hans01

Experienced Member
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Feb 17, 2014
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459
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Netherlands
@all

I use the HxC emulator with very much pleasure and have used him for all kinds of jobs with
very much success.

GOTEK in China makes a cheap floppy emulator for music instruments and some computer systems.
Many of us has tried to use it for the TRS-80, without any luck.

Some computer groups like Commodore and Amiga has found a way to reprogram the BIOS of
GOTEK (See GOTEK-Floppy_04)

As you can buy them at ebay for 20.-- to 25.-- euro. I ordered one and looked if I could modify the
Gotek. Reading all info of the groups and reading the info on the site off HXC2001 in found that they have
rewritten their software for their USB drive to use for the Gotek (See Gotek_inside)

I thought that it was doable. I opened the drive and extend it with a box with a display and 3 extra buttons
for a start. (See Gotek11)

What you have to do:
At first buy a cheap Serial programmer, I used one from Ebay (see I2Cprogrammer). Then go to the site from
HXC2001 and read all about the Gotek there is. Then you have to buy the modified boot-loader from
Jean-François DEL NERO for 10.--euro. He has done a great job, thanks for that.
Than you have to load the bootloader with the serial programmer in the Gotek. This is quite a job to arrange
this, due to the protection and a lousy programmer.

Then you are finished and you can use the Gotek in 3 modes now. The most usefull is the one with a serial display.
see (s-1500), you need one extra button or a set of 3)

The result is a very good floppy emulator, easy to use and with the power of the USB HxC.
You have to store the disks on an USB stick and can configure the emulator with a config file or a menu on the emulator.
It emulates only two drives :0 and :1, but this can modified with a switch or a patched cable.

To show you the result, there is a small video to show it.
https://www.dropbox.com/s/oq12k4vs6jjxpp0/video-2015-12-26-13-31-03.mp4?dl=0

It is a cheap way to add to floppys to your TRS80 and store up to 1000 disks on one USB stick.
I'am happy with the Gotek / HxC.
Many thanks to all the guys who let us use their knowledge.
Btw. It is NOT an easy project and you have to take some time for it.



gotek_inside.jpg s-l500.jpg gotek11.jpg
Gotek-Floppy_04.jpg I2Cprogrammer.jpg
 

jaquinn

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May 1, 2012
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91
Location
Auckland, New Zealand
Thanks for posting this. My GOTEK has been sitting in the queue of projects but now I know that it really works I might push it up the priority.
 

shirsch

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Aug 17, 2008
Messages
450
Location
Burlington, VT
Are you saying that the Gotek / HxC can emulate two drives at the same time, or do you mean it can be either one of 0 and 1? The documentation on the hxc2001 web site mentions that the Gotek can emulate only a single drive (unlike the Lotharek units).

I have also been playing around with a Gotek / HxC on my CP/M systems and not having a lot of success. At best I can get reads to work reliably, but writes tend to fail randomly. I have told them of this problem, but I think Jean-Francois and Jeff are busy with the holidays and don't have time to help.

Since it works 100% on a PC clone, my working theory is that something about the low-level timing or format is marginal for WD controller chips and ok for NEC (as used in almost all PC clones).

There are also a lot of things I do not understand about the HxCFloppyEmulator program. Started digging through the source code, but there is not much there for documentation or comments. Looks like a very steep learning curve.

Still, this looks like a worthwhile device and I'm hopeful that one or both of the developers will take an interest in the problems I'm experiencing.
 

Hans01

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Feb 17, 2014
Messages
459
Location
Netherlands
@shirsch.

They redirect you to the manual of the HxC SD version, I use for 2 years now.
You can support two drives at the same time. The Gotek version has the same menu structure, so I believe that you can support two drives at the same time.
I have problems with this option, but what else can you do with the drive-A / drive-B option ?
I asked this question at the HX2001, but got no answer until now.

There are a few file types which you can Read and Write, most dedicated file types you cannot write.
On their site (Current image support : *.HFE (RW), *.ADF (RW), *.ST (RO), *.IMG (RO).) So you have to translate your CP/M files to CPM.hfe files.
This must be done with most file types on the other emulators too. There is software in the package to do this easy.

The info about the Gotek emulator is surely very bad, what you want to know you cannot find.

On the other hand Jean-Francois and Jeff has done a great job to turn the Gotek from a useless device (for TRS-80) into a useful device.
If you use the normal mode with extra button and display you have a lot more options. I use beta version v3.0.6.6a firmware

I'am sure all the problems will be solved and the price for the software is very reasonable.
 
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shirsch

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Location
Burlington, VT
@shirsch.
The Gotek version has the same menu structure, so I believe that you can support two drives at the same time.

It's hard to understand how this can be the case. According to the schematic on the HxC web site, the Gotek unit has "wired OR" logic that routes SEL0, SEL1 and MTRON to a single line on the STM CPU chip. Unless the schematic is wrong, there's no way for the controller to determine which drive you want to access.

I'm a bit disappointed with the Gotek for other reasons, primarily that it won't work reliably on my CP/M systems. Reads of existing image files mostly work, but write operations fail randomly. Jean-Francois (Jeff? Same person?) claims that the unbuffered 3.3V logic inputs on the Gotek may be to blame. I'm going to try breadboarding a circuit using Schmitt-trigger bus receivers on the write-gate and write-data lines. Maybe that will help.

For the amount of money I have into it, I'm not unhappy. For read-only applications these devices will be helpful. Perhaps the firmware will improve to the point where writes are reliable.
 

Hans01

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Feb 17, 2014
Messages
459
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Netherlands
I just got an anwer from Jeff.

The gotek emulate only one drive. So set the S0 OR the S1 jumper (not both at the same time...). :-(

But what can you do with the Disk-A; Disk-B selection ?

I'm a bit disappointed with the Gotek for other reasons, primarily that it won't work reliably on my CP/M systems. Reads of existing image files mostly work, but write operations fail randomly. Jean-Francois (Jeff? Same person?) claims that the unbuffered 3.3V logic inputs on the Gotek may be to blame. I'm going to try breadboarding a circuit using Schmitt-trigger bus receivers on the write-gate and write-data lines. Maybe that will help.

It sounds very reasonable, interfacing 3.3 Volt with TTL should not be reliable, as wel I have no problems, i'am curious for the result.
 

Hans01

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I have been testing with the Gotek again.
The biggest problem is the USB stick. After testing for the read speed I think that about 20 Mb/sec is good.
Don't use fat32 to format.

No error anymore and very fast, no problems with format in TRS-80.
But I still don't know the use of the option Drive-a / Drive-b
 

Hans01

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Feb 17, 2014
Messages
459
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Netherlands
On the HxC 2001 site is an update for the Gotek available: Version HxCFEUSB_V3_0_16_3a.UPD.
Read the Gotek forum, item: New Alpha version Firmware - Volunteer Testers needed !
The Gotek is much more usable now and can compete with the SD version.

It runs perfect on a Model II if you use files in the .hfe mode. Of course on all other models too. :)
Just give it a try, you should like this cheap emulator.
 

MikeS

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Toronto ON Canada
Looks like as far as replacing a PC drive is concerned it's almost always a 3.5HD drive; does anybody have experience replacing a 1.2M 5.25HD drive in a PC?

TIA, m
 

MikeS

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Careful, Hans! The HxC will not replace SCSI nor IDE/ATA floppy drives! There are also 8" drives that do not use the Shugart standard interface. :)
... nor 26-pin drives, alas ;-)

But I was really asking about the cheap Gotek unit; they mention a 1.2HD "upgrade" - what's that about?
 

Chuck(G)

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I have no idea--it would seem to me that the 1.44MB version would work also as a 1.2M drive--you simply don't address sectors 16-18 on each track. The data rate's the same. The perceived RPM would, of course, be 300 RPM and not 360. But it should work for most applications.

Unless, of course, they're talking about the 1.23M NEC PC-98 drives, which use 1024 byte sectors.
 

Hans01

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Careful, Hans! The HxC will not replace SCSI nor IDE/ATA floppy drives! There are also 8" drives that do not use the Shugart standard interface. :)

Thank you Chuck(G) for this remark, you are totally right.
But of course I mean all Floppy diskdrives.

@MikeS If your floppy interface use a different cable (fewer wires), you have to build an interface cable between the USB- or SD-HxC adapter to connect to
your floppy diskdrive. (34 to 26 pins)

To complete my answer, our Australian friends has started a project to use the HxC emulator as a replacement for a hard disk.
It could use the images made for the FreHD interface and works on the Model 3, 4 and 4p. I used the latest available drivers to give it a try.
The interface works well and could replace a harddisk.
As there are some technical problems to solve and a lack of interesting from the Trs 80 community the project has stopped as far as I know.
 

MikeS

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I have no idea--it would seem to me that the 1.44MB version would work also as a 1.2M drive--you simply don't address sectors 16-18 on each track. The data rate's the same. The perceived RPM would, of course, be 300 RPM and not 360. But it should work for most applications.

Unless, of course, they're talking about the 1.23M NEC PC-98 drives, which use 1024 byte sectors.
Actually, I was thinking of using it as an 8" drive replacement so the RPM does matter.
 

MikeS

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Thank you Chuck(G) for this remark, you are totally right.
But of course I mean all Floppy diskdrives.

@MikeS If your floppy interface use a different cable (fewer wires), you have to build an interface cable between the USB- or SD-HxC adapter to connect to
your floppy diskdrive. (34 to 26 pins)
Well, Chuck and I were just teasing you a bit about all floppy drives; there are SCSI and ATA floppy drives (although admittedly not very common) that the HxC would not be able to handle.
https://www.cnet.com/products/teac-floppy-drive-fd-05hg-floppy-disk-drive-scsi-series/

To complete my answer, our Australian friends has started a project to use the HxC emulator as a replacement for a hard disk.
Sounds very interesting...
 
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