View Full Version : Kaypro 4x

September 22nd, 2017, 08:57 PM
I have a KAYPRO 4X in good condition but have been unsuccessful in finding any of the special floppies it requires or any original floppies. My backup is to convert it thru ROM replacement to another version of KAypro so I figured I would ask. Does anyone know of a source for software for the KAYPRO 4X. I have not seen any units for sale on ebay and I got this one for a great deal on this unit but without software it's a door stop.

September 23rd, 2017, 11:24 AM
You need to open up the Kaypro, and make a note of the current ROM/EPROM number. Once you have that, you can go to:


And download what you need for your version of ROM's.

Most of the files are .TD0 format (Teledisk by Sydex).

That should get you going.


September 23rd, 2017, 10:22 PM
It has ROM 81-326. The future for this Kaypro 4x will prob be on a shelf for a year or I might get a EPROM and try it with another model and different drives.

September 24th, 2017, 07:40 AM
I believe that I have the images for A Kaypro 4 (not sure of the ROM date) and the software to create actual disks (since I already have for a couple of clients, for various Kaypros), so, if you can't do it, get in touch with me.

September 24th, 2017, 10:48 AM
It uses the same floppies as the Robie and the machine used pre formatted floppies, the machine could not format disks in the weird 2.8MB format required.

September 25th, 2017, 07:31 AM
It uses the same floppies as the Robie and the machine used pre formatted floppies, the machine could not format disks in the weird 2.8MB format required.

The software I use allows me to format diskettes to a variety of different densities and, yeah, if you want a universal ROM, I can make those too.

September 25th, 2017, 09:22 AM
I ordered a ROM programer so that is prob what will happen with the 4X, it will get a conversion.

Have you been able to make a floppy for the 2.8MB drives?

September 25th, 2017, 09:33 AM
You can't just randomly swap ROMs between Kaypros and expect them to work.

Also, no Kaypro CP/M machine that I'm aware of ever used 2.8MB drives.

The Maslin archive doesn't include boot disks for the 4X, so if someone has them, please let me know - I'd be happy to get them online.


September 25th, 2017, 02:50 PM
Kaypro did sell some machines with the 160-track Super-density drives. Those were upwards of 2.8M. I believe the drives could be troublesome back when they were new... not sure of the odds today.

Kaypro did also endeavor to make a "universal ROM" but I'm not entirely sure of it's compatibility with any given system. I ran it on a 2X. That ROM required the "2.2u" version of CP/M. NOTE: "2.2u" was not a universal version of CP/M, though. It would only run with the Universal ROM (81-478a). I did some deciphering of hardware/software compatibility here, but I can't guarantee it's accuracy. http://sims.durgadas.com/kaypro/kaypromodels.html

September 25th, 2017, 10:54 PM
Thanks its worth a shot as its unuseable now with the 2.8 drives and current rom.

September 25th, 2017, 11:01 PM
The 4X and Robie used pre formatted Floppies. There was no way of formating these quad density drives on machine. They required special pre formatted discs due to a servo track.

I have not seen another 4X on ebay. This one is prob going to be used for parts to build a 4'84 or it will sit on the shelf until media appears.

September 25th, 2017, 11:03 PM
it appears they are 2.6 drives. i will pull one soon and take pictures.


September 26th, 2017, 06:06 AM
The only 2.8MB drives I've EVER seen were 3.5" drives that started to appear in the market long after Kaypro ceased manufacture of their CP/M systems. That being said, Chuck is probably a better source than I am. :)


September 26th, 2017, 08:13 AM
From what I've been able to gather, a special cutting head was used to make the diskettes for the 4X and that is why they were only available pre-formatted. Since I'm not about to recreate the diskette creation jig, I'm pretty sure no software is going to be able to reproduce them.

The universal ROM for the Kaypro line doesn't mention the 4X, so, you make be screwed all around on this unit.

September 26th, 2017, 08:57 AM
The Kaypro "Robie" (basically a reworked Kaypro 4) used the 2.8/3 MB Drivetec drives. They require preformatted media, as the media has embedded servo bursts in each track (for 2.8M use). Good luck in finding some. You can read ordinary "360K" media in the drives--and the reading will be twice as fast as normal, as the Drivetec drives spin at 600 RPM. Formatting and writing 360K however, carries the same burden that formatting and writing DD media in 5.25' PC HD drives incurs--you're not guaranteed to be able to read them on a real double-density drive.

Not long after the Robie, Drivetec went into Chapter 7 bankruptcy and assets were purchased by Kodak, who was licensing the technology from Drivetec anyway. Kodak developed the technology a bit and came up with a 6MB drive. The blank, preformatted media is very uncommon.

I recall hearing rumors about a 12MB Kodak floppy, but have never seen one.

The 3MB drives were also offered as a PC kit by DTC, called the TeamMate.

September 26th, 2017, 11:26 AM
From when I dug into the 81-478a "UROM" source code, it handles the DriveTec high density drives. But, if there is no media for it they are not of much use. Theoretically, you could replace the drives with standard 5-1/4 floppy drives, but I think it also requires a jumper change on the main board - maybe more. depends on the version of main board you have. We'll have to get those details and look at the schematics again.

September 26th, 2017, 12:11 PM
It paid $50 for it and its in great shape and will go on the shelf as a parts machine and the Mobo will be added to my wall of Mobos until it's needed some day.

September 26th, 2017, 01:55 PM
You may want to consult the service manual (with schematics) on bitsavers. The Robie is included.

October 5th, 2017, 12:59 PM
It would be great if someone figured out how to dump a set of original disks for the 4x/Robie ... maybe one of the original drives could be run off a Kryoflux?

October 9th, 2017, 06:09 AM
I'm astonished at the size of the drives. I'd never heard of them at all before this. I wonder why they chose those drives?