A quick google showed this is probably your motherboard and dip switch config:

http://stason.org/TULARC/pc/motherboards/A/AC … 8-ACER-710.html

Not sure it will help because I don’t see a setting for boot order.

in fact there is no switch dedicated to the boot sequence!

Does it TRY to boot from floppy and just not be able to, or doesn't it even try at all?

I'm just asking because it has DD floppy only and I hope you are not trying to boot from an MS-DOS 6.22 disk, which would be HD, of course.

Also, why did you delete the partition if you just wanted to re-install the OS?

No, he doesn't even try to boot via Floppy! When the hard disk is connected, he wants to boot exclusively via hard disk.

The floppy is a 720kb disk. It is the first disk of ms-dos 4.01. When the hard disk is disconnected, it works properly. I also tried the original DR-DOS 5.0 (720kb). But the problem is identical.

I don't know why I deleted the partition. I should have just formatted it.

The MBR probably still indicates an active partition when you deleted it with FDISK. The MBR is the 1st 512-byte sector on the disk. Yeah, FDISK is pretty dumb. Old PC especially 8086/88 BIOS is really simple. If the MBR says there is an active partition, then it will just boot from there. Perhaps the partition boot record is still intact even after FDISK deleted it, since it simply wiped the entry in MBR.

You probably want to zap the MBR to '0s' so that will allow you to boot from floppy and reinstall the DOS. If you have other PC that can access to MFM disk, then you can do it there. Or, perhaps there is a hot-key combination somewhere that will allow you to boot from floppy.

BTW, when it said "Missing Operating System", won't it boot from floppy if you hit 'ENTER' key?

What are the dipswithes regarding the floppy drive set to?

Think you may have only two options: Remove HD and controller and put in another board like 386 or 486, then boot from floppy and redo the partition, format and "sys" the HD.
OR- You might be able to just pull the 20 pin data cable off the HD (not the 34 control cable) then boot from floppy and gently reconnect the data cable, it may or may work but I would try that before pulling the HD and controller out.
I am assuming it is an XT single drive MFM controller, if it has a second HD port you could move the data cable to it and see if you can boot from floppy and see the HD (which would be logically/electrically D and not C)

Horun wrote on 2020-04-12, 17:13:

OR- You might be able to just pull the 20 pin data cable off the HD (not the 34 control cable) then boot from floppy and gently reconnect the data cable, it may or may work but I would try that before pulling the HD and controller out.

Honestly I was scared to suggest this, but this is something I would try too.

Unlikely to work, since the controller won't be able to read the drive's geometry from sector 0, so it won't just appear when connecting the cable. These cables are also not capable of hot-plugging, so you can easily cause damage if some pin makes connection before ground is connected. Better don't try it.

If at all, try this: with everything connected, let it try to boot. When it says "no operating system found", disconnect the HDD's Molex power cable and do a soft-reset of the system (that is, Strg+Alt+Del, don't just press reset). Let it boot from floppy and re-connect the power cable. If the controller isn't fully dumb, it should still know about the hard disk.

This is not true.

Vintage computers of this type without CMOS settings in battery backed memory, always boot from floppy drive FIRST, A, B in this order then hard drive C next.
Possible that settings via switch or jumpers was set to have no floppy present on the motherboard's.

You have mis-configured floppy system, hence not booting. Seen this happen. Get motherboard and floppy controller set up correctly and the floppy drive set. On 8088, that is either 360K floppy or 720K floppy drive. I have done that. Remember, ribbon cable's connector for floppy with twisted part is A:, If you have straight ribbon with two floppy connectors, then need to set up the floppy drive's jumpers.

Floppy drives jumpers has to be set correct depending on your floppy cable, non twisted or twisted.

Yes I had done that by mistake and got no boot from floppy and it went to C after trying the floppy or skipping. If not set up, usually computer will beep and say floppy drive A: seek failure etc.

Cheers,

Odd that it will boot from floppy if that HD is disconnected. My two XT's will not boot from B drive ever, only A whether no HD is present or not. You are probably right that something is not proper set on the floppy controller but it does seem a bit odd.

derSammler wrote on 2020-04-12, 18:59:

If at all, try this: with everything connected, let it try to boot. When it says "no operating system found", disconnect the HDD's Molex power cable and do a soft-reset of the system (that is, Strg+Alt+Del, don't just press reset). Let it boot from floppy and re-connect the power cable. If the controller isn't fully dumb, it should still know about the hard disk.

Yeah I said it may not work. Your idea is better. Is that Ctrl-Alt-Del ? OP situation is one reason I switched to using 8bit scsi cards and old small SCSI drives in my XT's (in those I wanted to keep as close to original in part dates). Hate MFM/RLL hd's 🤣

pentiumspeed wrote on 2020-04-12, 23:10:

This is not true.

What is not true?

pentiumspeed wrote on 2020-04-12, 23:10:

Vintage computers of this type without CMOS settings in battery backed memory, always boot from floppy drive FIRST, A, B in this order then hard drive C next.
Possible that settings via switch or jumpers was set to have no floppy present on the motherboard's.

Did you actually read the thread? Apparently not, because he can boot fine from floppy when no HDD is present, which rules out that the board is configured to have no floppy at all...

There must be a hotkey to enable boot from floppy when a HD is installed. Otherwise you wouldnt be able to boot e.g. copy protected games with a HD installed. Did you search for documentation of this or similar Philips PCs?

If you have the right equipment you can program a XT-IDE ROM. With this you can select whether to boot from Floppy, IDE or MFM hard disk...this should solve your problem.

Any chance there is something configurable on the MFM controller?

Post some pictures of mainboard + controller...

Is the a ROM on the controller? You could try to remove it. If it boots from floppy then, you can try access the disk via Speedstor...

Thanks to your advice, I solved the problem by moving the hard disk controller (including the hard disk) to the 486 computer with 16-bit ISA slot.
The hard disk was detected, but in this case I was able to boot from the floppy. I have installed DR-DOS 5.0 in Italian (I had the original floppies), then i have reconnected the controller and the hard disk to the 8088 computer, and the boot was successful.
It remains to be seen how to boot from floppy, for protected games (like winter games)!

Thank you all!

Good, except:

Still not right. Need to learn more about this unusual computer properly, this is reason I said no.

You could be booting on the drive B: then computer then oh, now have no hard drive, tries to boot from A first then skips.
PS: it should say floppy drive detect failure on boot up during executing POST bios right after memory count test. You should hear the floppy drive heads seek once with light illuminated on the floppy drive. If it is not saying it and no floppy drive heads seeking noise, that means the motherboard or controller on board the motherboard was turned off via jumpers or switch.

Fix that first due to mis-configuration. Then you will have a computer that works properly.

Cheers,

lutz79 wrote on 2020-04-13, 22:38:

Thanks to your advice, I solved the problem by moving the hard disk controller (including the hard disk) to the 486 computer wit […]
Show full quote

Thanks to your advice, I solved the problem by moving the hard disk controller (including the hard disk) to the 486 computer with 16-bit ISA slot.
The hard disk was detected, but in this case I was able to boot from the floppy. I have installed DR-DOS 5.0 in Italian (I had the original floppies), then i have reconnected the controller and the hard disk to the 8088 computer, and the boot was successful.
It remains to be seen how to boot from floppy, for protected games (like winter games)!

Thank you all!

Good Job! Glad you got the HD booting and working. Curious if you have tried to boot from floppy on the XT now that the HD is working ?

pentiumspeed wrote on 2020-04-13, 23:25:

Good, except: […]
Show full quote

Good, except:

Still not right. Need to learn more about this unusual computer properly, this is reason I said no.

You could be booting on the drive B: then computer then oh, now have no hard drive, tries to boot from A first then skips.
PS: it should say floppy drive detect failure on boot up during executing POST bios right after memory count test. You should hear the floppy drive heads seek once with light illuminated on the floppy drive. If it is not saying it and no floppy drive heads seeking noise, that means the motherboard or controller on board the motherboard was turned off via jumpers or switch.

Fix that first due to mis-configuration. Then you will have a computer that works properly.

Cheers,

He never stated which XT board he has but two of mine will never boot from their B drive no matter what I do. I have not tried from the Headland board but have from the Laser Xt/3 and the Luggable. Both have dual floppies and will only boot from A if C is not present. There is no way to set a boot order on them, is hard written into their very basic BIOS as A and C only. Which XT boards do you have that will actually boot from B if no HD and no disk in A ? Just curious...

The Motherboard is an Acer 710. The jumper configuration is correct. I have the original manual.