View Full Version : External floppy drive on a Philips P2000c?

November 6th, 2011, 11:19 PM
This past weekend, I decided to play around a little with my Philips P2000c, a "luggable" CP/M machine. Mine is a P2012 which means it is equipped with two 640K QD floppy drives. I got the impression those won't be able to read 160K disks, but since I haven't really tried I don't know if that is the case.

Anyway, somewhere on the Internet I have a faint memory reading about how to use the external floppy drive interface. It is a standard 34-pin story described in the operator's manual. My idea was that perhaps one can hook up a 3.5" drive and configure it as a 640K drive for simpler data transfer, assuming there is some PC software that can format a 3.5" floppy disk to a 640K format readable on the Philips of course.

However, I tried two 1.44 MB drives, one external Amiga drive and even one internal drive from my Olivetti PC-1. Some of them I managed to get the LED shine constantly, but neither I got any action when trying to access a drive. Possibly the drive needs to be jumpered to DS2 or DS3? Out of the ones I tried, only the PC-1 drive has visible jumpers but when I researched it on the Internet, I didn't find any good reference which jumper does what.

Am I barking up the wrong tree in my attempts of using a 3.5" drive? I have a few spare 5.25" drives, both 160/180K (single sided) and 80 track double sided which effectively should work as another 640K drive if I get it properly configured. However I don't have a suitable cable, since it would take a 34-pin cable with female card edge connectors in both ends! Where can one find those? I don't fancy hacking and splicing my own cable as previous attempts in that area have been total failures.

As an alternative, I suppose I should try a serial connection. I just need to figure out if the boot disk I've got contains any CP/M comms program. I suppose neither WordStar or CalcStar does, perhaps Basic could be used in worst case.

November 19th, 2011, 04:21 AM
It is possible to hook up 3 1/2" floppy drives to the P2000C and use them as 640k drives. The disk geometry of the Philips P2000C 640k drives is the same as the PC 720 k drives. There is a problem with the drive pin layout as used by IBM, which differs from the more or less standard used before that. This is usually fixable, see http://www.tim-mann.org/trs80faq.html#[20] or http://nemesis.lonestar.org/computers/tandy/hardware/model16_6000/floppyfix.html on how it is solved for a similar platform.

It usually requires configuration jumpers on the drives or custom cables. I tried it, with a Teac Teac FD-55GFR 193-U (http://www.oldskool.org/disk2fdi/525HDMOD.htm) today and could succesfully format and copy (with verify) a disk.I started with a 5 1/4" drive because mine have more jumpers to set.

Note you have to create a three drive configuration _and_ write it to the boot disk.

BTW, Drive LED continuous on can mean you reversed the drive cable. This can easily damage all disk in all drives.

IMHO, the simplest way to exchange data via floppies between a P2000C and a PC is connecting a 1.2M drive to the PC.

November 19th, 2011, 03:11 PM
Thank you for your advice. I will get back to it whenever I have additional time to fiddle around. Actually I do not own a 1.2 MB drive. I have some 80 track (96 tpi DD) drives, but I yet didn't find a PC or software where I could utilize it as such. Perhaps the easiest solution for many reasons would be to get a 1.2 MB drive and use it with 96 tpi DD media whenever possible. It might work for 80 track BBC Micro floppy disks too? At least I was able to write 40 track Beeb floppies with a regular 360K drive and Linux software.

November 20th, 2011, 02:20 AM
80 track DD is exactly what a 3 1/2" 720 k drive does, so you can use that setting in the BIOS. The 1.2 M format was not very common for pre-IBM machines, but it is logically the same as an 8" drive.
I never tried reading foreign floppies directly with Linux (always used a Catweasel / cw2dmk or ImageDisk with DOS), but if you can control the sector size (block size?), it should be possible.

November 23rd, 2011, 01:32 PM
There is a format definition for 22Disk for the Philips formatted disks (160kb, 640kb). All you need is a DOS-PC with a 720kb or 1.2mb 5.25" drive.