Amstrad 6128 disk drive success - UK Vintage Radio Repair and Restoration Discussion Forum

jay_oldstuff · 18th Jan 2015, 1:21 am

I'm not sure if this should be in vintage computers or home-brew, I've put it in vintage computers, mods please move if you see fit.

I've recently rekindled my interest in old micros and have been getting an old beeb master up and running with help from members of this forum.

Anyway the other day whilst up in the attic I come across one of my other vintage micros, namely an Amstrad 6128. These used an odd 3" floppy drive the same as the Amstrad PCW for which disks even back in the day where expensive and could be quite unreliable.

Casting my mind back I recalled that that particular computer the internal 3" floppy had failed and a friend and I had rigged it up to an old BBC 5.25" external floppy drive borrowed the 3" drive out of his mums PCW and downloaded (BBS bulletin board no internet back then) some software that allowed us under DOS to read the 6128's 3"disks on the PC and save them as a disk image.

We then found another piece of software running under DOS that allowed us to format 5.25" disks (single sided single density) that the 6128 could read so using this method we transferred all my 3" disks to 5.25" I used this setup for some time until the 6128 got superseded by an Amiga in the 1990's

I digress: pulling it out it still has the broken 3" floppy installed and a long ribbon cable coming out the back. now wouldn't it be nice to get this back into working order? I know I can fix the 3" internal drive these drives use a drive belt which failed with age and sure enough when I opened the drive up the belt is in bits so I order a service kit including new belt online.
The problem is the disks, I do have a few (about 10) 3" disks but all have software on them for my Tatung Einstein and I don't really want to touch them.

After a bit of research online I found it is quite possible to connect a second floppy drive up to the 6128 and it can be either 3" 5.25" or 3.5". I chose to use a 3.5" drive and following instructions found online successfully got it connected up and running as drive B. The external disk drive connector on the 6128 is the same as on the back of a 5.25" disk drive and a PC floppy cable with the twist removed is what is needed to connect between the back of the 6128 and the disk drive. Actually I used an old BBC disk drive cable as I had a spare, it's slightly longer and doesn't have the twist. I am using a PC 3.5 HD disk drive of about 2002 vintage but to be honest it shouldn't matter.

Now if you just connect an old PC drive with the cable to the 6128, power the computer and drive it will just sit there and do nothing, that is because the drive ready signal is different between a PC drive and the drive a micro is expecting, this problem can be got around by shorting pin 33 to 34 (yes it makes the drive light stay on but it works)

With that done you have a fully working external drive B - the problem is some commercial software will not load from drive B only drive A and I don't really want to be removing the original 3" drive and modding the case to fit an 3.5 internally. However if you short pins 11 to 12 while the system is running the drives will swap even though the internal drive is setup as DF0 and the PC drive by default DF1 remove the short and they swap back.
One last mod is head swapping. The original 3" disk drives are single sided to read the other side of the disk you eject it and turned it over like you do with BBC 5.25" disks, not possible with a 3.5" disk but if you connect pin 31 to 32 then the drive will read from head two

Now none of this is new information, it's all there on the web however every one of these setups I've seen has had the bare drive and old PC psu and bits of wire all over the place and I wanted something a bit neater. In my junk box I had an external 3.5" hard drive enclosure that although it would power up a hard drive the SATA to USB interface had failed so with this I had both my enclosure and PSU all I had to do was disable the electronics inside, mount the 3.5" floppy and add some switches to the rear for drive select and head select. I'm rather pleased with the results.

As for the old DOS software I used all those years ago there is now a programme out free to download called CPCdiskXP that not only formats the disks for the 6128 it also allows your to download DSK images from the net and transfer them to disk for direct use on the 6128.
I'm off now to go play some manic miner

Jay

Boater Sam · 18th Jan 2015, 5:59 am

Dis all this many years ago with PCW 8256 and PCW 9512. Removed all the 3" drives and replaced with 3.5".
Had it all working without any extra switching but neither would boot from drive B .
Intrigued that you found a way to boot from B, never thought of that.
As an aside, I still think that the PCW word processors were great, despite the name on the front. We had loads of them running the business, accounts and stock control, in fact everything but internet.
Sam.

18th Jan 2015, 1:21 am	#1
jay_oldstuff Octode Join Date: Jan 2005 Location: Hyde, Greater Manchester, UK. Posts: 1,074	Amstrad 6128 disk drive success I'm not sure if this should be in vintage computers or home-brew, I've put it in vintage computers, mods please move if you see fit. I've recently rekindled my interest in old micros and have been getting an old beeb master up and running with help from members of this forum. Anyway the other day whilst up in the attic I come across one of my other vintage micros, namely an Amstrad 6128. These used an odd 3" floppy drive the same as the Amstrad PCW for which disks even back in the day where expensive and could be quite unreliable. Casting my mind back I recalled that that particular computer the internal 3" floppy had failed and a friend and I had rigged it up to an old BBC 5.25" external floppy drive borrowed the 3" drive out of his mums PCW and downloaded (BBS bulletin board no internet back then) some software that allowed us under DOS to read the 6128's 3"disks on the PC and save them as a disk image. We then found another piece of software running under DOS that allowed us to format 5.25" disks (single sided single density) that the 6128 could read so using this method we transferred all my 3" disks to 5.25" I used this setup for some time until the 6128 got superseded by an Amiga in the 1990's I digress: pulling it out it still has the broken 3" floppy installed and a long ribbon cable coming out the back. now wouldn't it be nice to get this back into working order? I know I can fix the 3" internal drive these drives use a drive belt which failed with age and sure enough when I opened the drive up the belt is in bits so I order a service kit including new belt online. The problem is the disks, I do have a few (about 10) 3" disks but all have software on them for my Tatung Einstein and I don't really want to touch them. After a bit of research online I found it is quite possible to connect a second floppy drive up to the 6128 and it can be either 3" 5.25" or 3.5". I chose to use a 3.5" drive and following instructions found online successfully got it connected up and running as drive B. The external disk drive connector on the 6128 is the same as on the back of a 5.25" disk drive and a PC floppy cable with the twist removed is what is needed to connect between the back of the 6128 and the disk drive. Actually I used an old BBC disk drive cable as I had a spare, it's slightly longer and doesn't have the twist. I am using a PC 3.5 HD disk drive of about 2002 vintage but to be honest it shouldn't matter. Now if you just connect an old PC drive with the cable to the 6128, power the computer and drive it will just sit there and do nothing, that is because the drive ready signal is different between a PC drive and the drive a micro is expecting, this problem can be got around by shorting pin 33 to 34 (yes it makes the drive light stay on but it works) With that done you have a fully working external drive B - the problem is some commercial software will not load from drive B only drive A and I don't really want to be removing the original 3" drive and modding the case to fit an 3.5 internally. However if you short pins 11 to 12 while the system is running the drives will swap even though the internal drive is setup as DF0 and the PC drive by default DF1 remove the short and they swap back. One last mod is head swapping. The original 3" disk drives are single sided to read the other side of the disk you eject it and turned it over like you do with BBC 5.25" disks, not possible with a 3.5" disk but if you connect pin 31 to 32 then the drive will read from head two Now none of this is new information, it's all there on the web however every one of these setups I've seen has had the bare drive and old PC psu and bits of wire all over the place and I wanted something a bit neater. In my junk box I had an external 3.5" hard drive enclosure that although it would power up a hard drive the SATA to USB interface had failed so with this I had both my enclosure and PSU all I had to do was disable the electronics inside, mount the 3.5" floppy and add some switches to the rear for drive select and head select. I'm rather pleased with the results. As for the old DOS software I used all those years ago there is now a programme out free to download called CPCdiskXP that not only formats the disks for the 6128 it also allows your to download DSK images from the net and transfer them to disk for direct use on the 6128. I'm off now to go play some manic miner Jay Attached Thumbnails __________________ The light at the end of the tunnel is probably the headlight of an oncoming train

18th Jan 2015, 5:59 am	#2
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Amstrad 6128 disk drive success Dis all this many years ago with PCW 8256 and PCW 9512. Removed all the 3" drives and replaced with 3.5". Had it all working without any extra switching but neither would boot from drive B . Intrigued that you found a way to boot from B, never thought of that. As an aside, I still think that the PCW word processors were great, despite the name on the front. We had loads of them running the business, accounts and stock control, in fact everything but internet. Sam.