MDS 225 Update

From: Dave Mabry <>
Date: Fri Dec 17 15:59:40 2004

river wrote:

>Thanks for the reply. I went and loaded all those docos regarding the Series 2XX. Great stuff.
>I cleaned up the connectors to the IO board and now the floppy drive engages upon reset. I ran the diags and all system work and even the floppy drive passed its tests with a scratch disk. However, I get a disk error when I boot the ISIS-II system disk. I tried a few other disks and the ones that are double-density all give a "disk error", yet the single-density ones just say "not bootable".
Sound like your "disk error" diskettes are probably double density. The
IOC board only controls the drive in single density mode.

The message "not bootable" has to be coming from the diskette itself.
The boot rom in the MDS has no such message. So what you have is a
"data" diskette, or one that was formatted by some operating system with
the boot sectors containing the code to print out that message when it
has execution transferred to it. That's how ISIS non-system disks would
do it. At least it shows that your controller and drive are working.
You just need a boot disk in single density.

>So, I guess I need to find a single density 8-inch ISIS-II boot disk. I can't use the one from my Series-4 'cos it uses 5-1/4 disks. THe unit also came with a dual disk drive array - yet another amazingly heavy blue box, and an expansion chasis. It appears that there are no cables to attach the disk array. The 225 has the two disk controller cards in the chasis and the cables are routed to the J8/J9 connectors, but I beleive there is a cable that I require to attach from these connectors to the disk array. I'd love to get the 225 fully operational 'cos it came with the ICE-80 (which I cannot use on the Series-4, which has an ICE-85B), ICE-51 and ICE-49. I especially want to use the ICE-80 so I can do some 8080 development (may as well use the stock of chips I got).
>I'm gonna see if I can pull out the single-density drive in the 225 and put in one of the double density drives from the array. However, before I do that, does anyone know the cable pinouts - 'cos I might try and make a cable first. Or does anyone know where I can get a cable?
The drive in the 225 can do either single density or double density
depending on what controller hardware it is connected to. You won't do
anything by replacing it. If what you have is an Intel external floppy
disk chassis made for the MDS, then there are people here who can get
you the wiring diagram for the cable between the MDS and the floppy chassis.

Ask nice, and STOP threatening to make your systems into parts!

>In the final run, if I can't do anything much with it, I can always use the parts for spares and other stuff.
>Oh, final question... I also have an iPDS that's been waiting for a boot disk. Can I use my Series-4 ISIS-II disks in this unit? Will it boot, or is this unit doomed to be pulled apart for spares also?

The Series-IV and the iPDS are two totally different beasts. Different
cpu, different operating systems. The only thing the same is the
physical format of the drives. DSDD 96 tpi.

All these threats to make your systems "spare parts" machines won't get
you much sympathy here.

I can e-mail you a TELEDISK image of a boot diskette for the iPDS. You
will have to make the boot diskette from a PC with a 1.2MB "HD" drive on
it and it will probably need to be somewhere in the range of a 386 or
486 vintage PC since the images were made on a 16MHz 386SX system.
Received on Fri Dec 17 2004 - 15:59:40 GMT

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