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Chapin Ratte

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Aug 3, 2024, 1:00:11 AM8/3/24

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Hello everybody,
I have a Philips NMS TC-100 with 8088 processor. The defective MFM hard drive has been replaced with another MFM hard drive. In this new hard drive there was a French version of DOS.
I wanted to replace the operating system with an English version, and then I deleted the primary partition with fdisk.
On reboot, I get the error "missing operating system" and it doesn't boot from the floppy.
If I detach the hard disk, the computer correctly boots from the floppy disk. But of course I can't install the new operating system on the hard drive.
The BIOS menu cannot be accessed on this computer. The settings can be changed through the dip-switches on the motherboard. But on the original computer manual, there is no way to change the boot sequence. There is no switch that allows you to change the boot sequence.
Is there a way to force boot from the floppy disk without detaching the hard disk? Otherwise I can't install the operating system!

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.

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)

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.

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.

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.

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.

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 ?

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?

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)!

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.

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...

Historically, computers with Intel 8088 chips have shipped with proprietary BIOS firmware. But developer Sergey Kiselev has been working on an open source BIOS for select 8088 devices for about a dozen years, and this month Kiselev decided the 8088 BIOS code was stable enough to graduate to version 1.0.0 status.

Liliputing's primary sources of revenue are advertising and affiliate links (if you click the "Shop" button at the top of the page and buy something on Amazon, for example, we'll get a small commission).

The 8088 BIOS is an open source BIOS for 8088 based computers. I've been developing it since 2010, primarily to support my Xi 8088 and Micro 8088 projects. This BIOS is also used in the NuXT Turbo XT project.

Book8088 system that appeared early 2023, uses 8088 BIOS in violation of GNU Public License. In particular, the license and the copyright have been removed, also the distribution of the source code is uncertain.So far the manufacturer of Book8088 failed to comply with the terms of GNU license, citing non-sense excuses about not being able to sell systems that have software they don't own the copyright to (somehow everyone else does sell Windows and Linux systems, although they don't own the copyright).

By popular demand from the community I added official support for Book8088 to the 8080 BIOS. And now I offer preprogrammed ROMs with the BIOS for the folks that are unable to program the EPROMs themselves.

We look for the most active & best members of the Tindie community, and invite them to join. There isn't a selection process or form to fill out. The only way to become a Tindarian is by being a nice & active member of the Tindie community!

In the recent past I have discussed the Book 8088 and the Hand 386, which are newly made vintage computing systems. I concluded that those products, although not uninteresting were rather flawed. The Book 8088 was by far the more disappointing of the two devices. I have also been made aware of a project which tries to fulfill a similar niche, the NuXT motherboard. The NuXT is an 8088-based motherboard you can buy brand new and can really fill that IBM PC-clone hole in your vintage collection. While I do not own one of these, I have read and seen enough about it to give my thoughts on whether this product would be right for you.