View Full Version : Wierd Amstrad PC1512 Priblem

Phil Saunders
May 25th, 2014, 08:58 AM
Hi, everyone - newbie here.

Been reading this forum for a while now - until I found this I thought I was the only one with an interest in this ancient hardware.....

I'd be really grateful if anyone could help me out!

My problem is - I've recently un-earthed a PC1512 - complete with box, manuals, system disks and everything - only strange thing is that both floppy drives have been replaced with non-Amstrad versions (still 360K, but one is a Chinnon, and the other is a Sharp).

The system works exactly as it should - both drives can be accessed, both will read/write/format, and the disks produced are readable by both drives, and other machines.

Now for the problems -

1) If I boot to MS-DOS (as opposed to DOSPLUS) and use the DISKCOPY command, the target disk is unuseable. The copy completes successfully, but a DIR of the target disk displays a single filename consisting of garbage characters (although it's the same garbage every time), and the free space remaining on the disk is different to the source disk. This occurs whether I use both drives, (DISKCOPY A: B: ) or a single drive (DISKCOPY A: A: )

2) If I install a hard drive controller, the machine will not boot MS-DOS (which means I can't FDISK a hard drive). This is caused by the presence of the controller, NOT the drive. To prove this, I installed JUST the controller (no drive). I got the expected 1701 POST error, followed by the expected 'Insert a system disk' message. If I use a DOSPLUS boot disk, the system boots. If I use an MS-DOS disk (3 tried, including the one that boots without the HD controller) the system just hangs - spins the disk, but no boot, and no error messages. If the disk is removed, however, the system immediately asks for a system disk ........

A bit embarrassing really - I used to install these professionally when they were new - but this has really got me stumped.

Anyone seen anything like it before?

May 25th, 2014, 09:22 AM
C800 I think isn't free in the PC1512, hence there could be an address conflict with the controller BIOS. If the controller provides the option to use a different address, like D000 or D800h, try those.

Phil Saunders
May 25th, 2014, 10:29 AM
Hi - thanks for that hadn't thought of that it's worth a try. Next problem - the controller is a Acculogic S-IDE. 3 jumpers - 1 labelled IRQ (5 and 2 are the options), the other 2 are simply labelled W1 and W2 -

The controller is on a hard-card, along with a WD drive that is probably toast anyway.

pearce_ll - Just checked your user name - are you the guy that makes the XT-CF cards, and would one of those work?

May 25th, 2014, 11:36 AM
pearce_ll - Just checked your user name - are you the guy that makes the XT-CF cards, and would one of those work?

Yes, those are mine :) They should work; we might need to modify one slightly to use D800 as it's base address.

May 25th, 2014, 11:48 AM
My guess would be either bad RAM or a bad system disk (i.e. corrupt diskcopy.exe). I can't think of anything else that would give that symptom for the first problem if the drive otherwise reads, writes and formats successfully.

Bad RAM might account for the second problem as well. I think the address conflict is a red herring - C8000 is the address of the HD ROM on a machine with a hard drive but if this was always a dual-floppy machine then I'm pretty sure it won't have that ROM.

Phil Saunders
May 25th, 2014, 11:55 AM
Thanks people - I'll remove the HD controller for now & boot GEM off floppies - If I can run that successfully I'll assume the RAM is OK (no diags to hand unfortunately).

James - I'll pull another hard drive controller from something else with the BIOS unquestionably at C800 and see if it boots. If it does, I'll order a CF card.
Now that I think about it, this controller was once in a machine that had a bad PSU, so I suppose it might have got 'spiked'.

May 25th, 2014, 12:06 PM
Just checked the tech ref here: http://www.seasip.info/AmstradXT/1512tech/section1.html and it says "The optional Hard Disk controller uses the 20K byte address range from C8000 to CBFFF." So it should be free unless there is another controller in there or one on the motherboard?

I'd be looking at RAM too, but that's not always as simple as switching out a chip. I've got one XT motherboard, and an XMS card like this - I'm fairly sure they need to be recapped. The XT however, still runs reliably at 4.77Mhz, so it might be worth seeing if diskcopy works for you at the slower speed (if you can, I don't know how on a 1512).

Edit: Booting stuff up is a practical way to test the RAM, but make sure you load applications etc as well, fill up that memory. Alternatively try Checkit or another diagnostics tool.
Edit: And make sure the HD controller is on IRQ5

Phil Saunders
May 25th, 2014, 02:09 PM
OK guys that's given me something to work with. Hope it's not a RAM problem there's only 512k in the machine and it's soldered in to the motherboard. I'll see if I can find a RAM test utility on 5.25 disk.

It's strange that it will boot DOSPLUS - it's a pity that none of the DOS commands I'm familiar with work! Is there a DOSPLUS equivalent of FDISK or even DEBUG?

Phil Saunders
May 26th, 2014, 11:12 AM
Well I've been working with the Amstrad all day ......

I borrowed the entire hard drive sub-system out of another machine - it works fine!

I found another 'status unknown' XT-IDE hard drive and attached it to the suspect Acculogic controller - hard drive booted DOS 3.2!

However - the machine STILL won't boot from a DOS boot disk in drive A:. Strangely, it WILL boot DOSPLUS.

Possible clue - FDISK suggests there is a second hard drive (Option 5 - Select Next Hard Drive is displayed). There isn't, and selecting this option fails.

While I had the machine apart, I upgraded the RAM to 640K and tested it with CHECKIT - no problems.

Soooooo - any suggestions how to get the machine to boot from floppy with the hard drive installed?