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Making the A drive start as B.

Are you talking about on the disk drives themselves or the computer itself?

If the former, you will have to state the manufacturer, make and model of the disk drives.

If the later, you will have to state exactly what you have got.

There are some ways to do this in software, others in hardware - but to understand what your setup is will make it much easier to specify a solution for you.

Just out of interest, why do you need to swap A and B over?

Also, welcome to VCFED...

Dave

Dave
 
It entirely depends on what hardware you have. Before the IBM PC, drive select was done with jumper blocks on the drive board. Every brand of drive had its own way, but usually it was DS0 = A and DS1 = B. A third drive would be selected with DS2, but the fourth drive select could vary. I think the TRS-80 originally used DS3 as side select for double-sided drives. The FDC chip does not control the drive selects, it's just an I/O port latch.

With the IBM PC, all drives were set as the second drive select DS1 (often with soldered jumpers), and drive selection was done by flipping a few wires in the ribbon cable to swap the drive select wires for drive A. Presumably this was so that they could have both drives listed as the same part number for replacements.

You could also theoretically swap drives in the BIOS, but that would not let you boot from the B drive, because you have to load the OS first.
 
On an IBM PC or compatible, unpack the BOOTB utility, format a disk in your drive A: , issue the command "BOOTB A:"
This will destroy the original boot sector of this disk. Don't use it on valuable disks.
After that, you leave the modified disk in drive A: and put a bootable disk in drive B: and restart.

Robert
 

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daver2 said:
Are you talking about on the disk drives themselves or the computer itself?

If the former, you will have to state the manufacturer, make and model of the disk drives.

If the later, you will have to state exactly what you have got.
Click to expand...

Since the OP is not replying here (maybe the moderation lag is causing a problem), I'm guessing he doesn't understand the questions. I'm going to take a stab at it. I think he's trying to resolve the probelm with his Kaypro 1 that he posted about here:

https://forum.vcfed.org/index.php?threads/kaypro-1-no-operating-system-on-this-disk.1240070/

Since the K1 isn't booting from the A: drive, he wants to see if he can make the system boot off the B: drive which would (of course) indicate that the A: drive is bad.

rfka01 said:
On an IBM PC or compatible, unpack the BOOTB utility, format a disk in your drive A: , issue the command "BOOTB A:"
Click to expand...

While this is a good suggestion in the IBM compatible world, it will unfortunately not work for most non-IBM CP/M systems. Also, if I'm right about why the OP wants to switch drives, the fact that the A: drive isn't finding an operating system, might mean that this kind of software solution won't work in this case anyway.
 
This may be the same person that posted a similar question (at almost the same time) on the Kaypro facebook group, in which case this is a Kaypro system and the jumpers on the drives need to be switched. He may have gotten what he needed from that group, and that plus the moderator delays are probably leading to the lack of response here.
 
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