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Help needed with Gotec

Started by Cerbrus2, 19:39, 12 October 22

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Cerbrus2

Hi guys, I recently got a PCW 8256. 

The PCW came with no software, but it turned on and displayed a green screen. So i decided to grab it as it was realy cheap. 

I ordered some software from ebay. and a Gotek. I couldnt find a PCW Gotek. so I bought one that was for a cpc 6128. And as I have a 3D printer. I figured i would print the available drive mount on thingyverse. 

However. i got a load of games.dsk images, and the cp/m plus.dsk images. put them on a fat32 USB drive. and connected it to the PCW.

it displayed FlashFloppy v3.3  32kb on the screen. with the option to enter the menu, and then menu gave me factory reset, update firmware and configure FF OBD. configure does nothing. So i decided to try a different version on cpm plus, and when i put the USB drive into the PC to change the file. the USB is no longer recognised. its like it is completly dead. Tried A second USB. and it did the same thing. 

Can anyone help me out. or give me a link to a tutorial. as im struggeling to find information on this. 

on the plus side the actual 3" disk that i bought off of ebay with cpm plus. works perfect. however i would realy like to get gotek working as i realy want to play some Zork, or hitchhikers :P

cj7hawk

You plugged the floppy power cable straight into the Gotek I assume. The 5v and 12v are reversed compared to a 3.5" drive, so you will have fried the USB sticks, though the good news is that the Gotek often survives.

Check the voltage carefully with a multimeter and correct if necessary. ( Remove the 12v line from the Gotek altogether - it isn't used... Also, the colours are different on the voltages compared to what you may expect, so make sure to measure them with the multimeter ).

Then if all is correct ( you may have to jumper the motor and select lines also ) you should be able to read a single drive. Lines will appear on the screen as you boot CP/M

If you want to read two drives ( eg, A: and B: ) you need some additional circuitry - eg, 74ls32 to perform some decoding on the cable and drive the Gotek and the original drive.

Regards
David

eto

Quote from: cj7hawk on 11:44, 14 October 22You plugged the floppy power cable straight into the Gotek I assume. The 5v and 12v are reversed compared to a 3.5" drive, so you will have fried the USB sticks, though the good news is that the Gotek often survives.
wasn't it just the wire colours that are swapped but still the same pin sequence?

cj7hawk

Quote from: eto on 12:28, 14 October 22
Quote from: cj7hawk on 11:44, 14 October 22You plugged the floppy power cable straight into the Gotek I assume. The 5v and 12v are reversed compared to a 3.5" drive, so you will have fried the USB sticks, though the good news is that the Gotek often survives.
wasn't it just the wire colours that are swapped but still the same pin sequence?

No, it's the pin sequence.

The MF2 drive (3.5") and the CF2 drive (3") both have the same 4-pin molex connector for power, and centre two are both ground.

But they have reversed voltages... 5v and 12v are swapped... So Plugging an Amstrad FDD power cable to a Gotek will put 12v on the 5v line, and the Gotek does not use the 12v line, so will only get a single supply of 12v.

The chip the Gotek uses often survives this process, which is pretty amazing in itself, but USB sticks are memory oriented and work at 5v.... When 12v hits them it fries the USB stick pretty quick. Sometimes it sees the directory once, but not for long.

I made the same mistake myself when I started working with Amstrad drives on Sinclair machines, which is how I know what happens to the USB stick.... And I recognized the description the OP made... Now I make adapter PCBs that include the power plug, and prevent it being put on in a reversed way, but adapt the 26pin cable to 34 pins and power at the same time.

But if you've just got the 26 to 34 pin adapter, or you wired your own cable, you are at high risk of seriously damaging something if you're not aware of it.

Seems the OP also wants to keep the existing FDD, so keep in mind that two drives will clash due to the reduced number of cable lines available on the Amstrad. You need to introduce a 74LS32 chip into the cable as an OR gate ( active low, so it's like a negative AND gate ) across both the Disk Select line and the Motor Enable line and feed the output into the Gotek Select line so that the Gotek and existing CF2 drive don't clash. Otherwise they will both turn on at the same time, and both will try to write data to the data line, which prevents operation of both.

Troubleshoot the Gotek with the Amstrad drive disconnected, then once you have it all working, install the OR gate modifier so it works correctly.

I've been meaning to turn the adapter into a circuit board to make it easier for people to do, but haven't gotten around to it yet. Also I have a very night FDD adapter for the 9512 which I put the design into the public domain so anyone can print it. It was the original "45 degree screen" model, and is still the nicest IMO, so would recommend that if the OP hasn't comleted their installation. I don't sell it, but the files were made free ( and are linked in another thread on this site ) so you can get a friend with a 3D printer to make it for you. :)

David

Cerbrus2

Right got it all working on the Gotek. And even got the 3" working. But without the gotek installed.

Issue with the goteck was that I switched the 5v and 12v wires as has been posted online. Only to fined that the adapter that came with my gotek did this for me. So now that is sorted. I have a vertical drive mount printing next to me right now. And when that is done. I would very much like to get the a 3" a drive that came with the pcw 8256. And mount it as a B drive. Question is. Are their any jumper setting I need to de solder or change on the A: drive to get it to work as a B: drive along with the gotek.

robcfg

The problem you'll find is that CP/M expects the 2nd drive to be a 720KB one, instead of the regular 180KB one.

So, you'll need to configure your CP/M disk to reflect your configuration.

Changing the drive from A (DS0) to B (DS1) depends a lot on the model of drive you have.

Which one is it, by the way? EME-15...?

cj7hawk

Quote from: robcfg on 18:39, 15 October 22The problem you'll find is that CP/M expects the 2nd drive to be a 720KB one, instead of the regular 180KB one.
I thought that was the 9512+ and the 720 was "A:"?

IIRC (and I might be wrong), the 8256 is 180K both drives. Most of the 8256 disk images I've seen are all 180K.

David


cj7hawk

Quote from: Cerbrus2 on 13:39, 15 October 22Right got it all working on the Gotek. And even got the 3" working. But without the gotek installed.

Issue with the goteck was that I switched the 5v and 12v wires as has been posted online. Only to fined that the adapter that came with my gotek did this for me. So now that is sorted. I have a vertical drive mount printing next to me right now. And when that is done. I would very much like to get the a 3" a drive that came with the pcw 8256. And mount it as a B drive. Question is. Are their any jumper setting I need to de solder or change on the A: drive to get it to work as a B: drive along with the gotek.
You're missing a signal and need to generate it with some external circuitry.

Take the Motor Select signal and the Drive Select signal for the Gotek ( you can use jumper cables to take them from the Gotek board if you have soldered in all the header pins ) and take 5v and GND and wire these up to a 74LS32 chip on two inputs, and take the output of the gate and drive this into the Gotek Select line, regardless of whether you set it for A or B.

Without this, the Gotek will activate at the same time as the B: drive and will interfere with reading it.

Have a look at this image to understand:



See the little blue addon? THat's a 74LS32 wrapped in heatshrink. I only use one of the gates..  The inputs to the first gate are on Pin 1 and Pin 2 and the output is on Pin 3. Ground to Pin7 and +5v to Pin 14..  It just jumpers onto the Gotek and performs the drive select decoding to make it work properly.

This is necessary due to how the Gotek is designed, and how the Amstrad provides the signals on the 26 pin header.



robcfg

Quote from: cj7hawk on 00:11, 16 October 22
Quote from: robcfg on 18:39, 15 October 22The problem you'll find is that CP/M expects the 2nd drive to be a 720KB one, instead of the regular 180KB one.
I thought that was the 9512+ and the 720 was "A:"?

IIRC (and I might be wrong), the 8256 is 180K both drives. Most of the 8256 disk images I've seen are all 180K.

David


I've double-checked the PCW 8256/8512 manual, volume 1, and it states that the second disk drive is a FD-2 unit which uses CF2-DD disks with 720KB of capacity.

So, if you're using a standard CP/M disk for PCW, the drives will be configured like that. I'm not sure if the drive reads single-side formatted disks.

Maybe you can configure it to have the single-sided drive as drive B.

JohnElliott

Quote from: robcfg on 11:50, 16 October 22I've double-checked the PCW 8256/8512 manual, volume 1, and it states that the second disk drive is a FD-2 unit which uses CF2-DD disks with 720KB of capacity.

So, if you're using a standard CP/M disk for PCW, the drives will be configured like that. I'm not sure if the drive reads single-side formatted disks.

Maybe you can configure it to have the single-sided drive as drive B.
It will read single-side disks, double-stepping the drive because the track spacing on 180k 3" discs is double the track spacing on 720k 3" discs. This tends to cause awful problems when the drive is really a 3.5" or a Gotek.

CP/M Plus 1.14 or 1.15 (and LocoScript 2.30+) support a 180k drive B: - you need to source a copy of B180.FIB and put it on the boot disc.

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