• Please review our updated Terms and Rules here

Computerland with BC286 Adaptec ACB2010A

falter

falter

Veteran Member
Joined
Jan 22, 2011
Messages
6,570
Location
Vancouver, BC
So I have a BC286 now and it came with what I think is a 32mb Miniscribe MFM drive. It also has some sort of combo floppy/ide controller with nothing attached on the IDE side.

The BC286 has a built in BIOS configuration program. The battery is long dead, so I have to go in via CTRL-ALT-ESC to set parameters each time I power up.

So far nothing seems to get the hard drive working.. the drive spins up and makes its usual startup clatter.. but then flashes what appears to be a pattern endlessly on its LED. The machine complains of a problem with fixed disk controller 0.

I also tried setting the drive up under the secondary disk controller in BIOS.. in case maybe the IDE controller was considered controller 0.. but that just gives me a 1701 error.

It has been a long, long time since I messed with MFM hard drives. The manual for the card mentions having to debug a certain memory address to put in drive parameters.. im not sure how that info is kept or how it jives with the info kept in BIOS.. or how MFM controllers and IDE controllers prioritize themselves.. anyone have any experience with this? Many thanks!!
 
An IDE hard disk drive is in fact the a drive that combined the original circuit with the one found on the MFM card (the 16-bits AT version, not an 8-bits XT one). That is the reason why you can place an IDE drive in an "ancient" IBM AT without any problem: the computer doesn't see any difference. An IDE card card only contains an address decoder and some buffers. As they are, more or less, the same, there is no prioritization: different hardware addresses should take care of that. And that is what does happen in your machine, IMHO.

Have you started the machine with only with the MFM card? If you are sure that the given parameters for the HDD are correct, the machine should start to boot from the HDD. If not, either wrong parameters or some broken hardware.

And you keep having problems, why not using the FDC/IDE card in combination with an IDE HDD?
 
I found a pdf for the Adaptec controller, and I guess I have a few observations:

This appears to be an 8-bit XT style controller with a built-in BIOS? It also says it uses XT-style addressing/IRQ/DMA settings. If this actually applies to what’s in your computer then:

1: This is an odd choice for an AT. It should “work”, but it’s not really optimal for it and I wonder why it’s in there instead of a proper 16 bit controller.

2: The AT BIOS setup program is going to have no idea how to set this up. This is a completely self-contained dingus that will provide its own low-level disk routines, so far as the built-in BIOS is concerned this isn’t a hard disk.

3: Per the info in the manual the only way to run the setup/format program is to jump to the proper address in memory with debug. Only thing you should be doing in the main BIOS setup is telling it you don’t have a hard disk.

4: Also per the manual the controller can either be jumpered to use a hard coded disk parameters setting from a table in its BIOS, or you can set it to a user-definable mode which writes auto config information onto the hard disk itself when you run the formatter. The manual doesn’t mention any 32MB disks so I’m guessing yours is set up that way.

So… I think what you need to do is verify the jumpers are set for “user defined”, look up what the right geometry is for whatever model drive you have is, and try following the instructions in the manual to see if you can reformat the disk. My gloomy prognosis is it’s dead as a door nail because if it were physically working the controller should just read the autoconfig info it wrote in the first place and fire up, it shouldn’t care one whit about a dead CMOS battery. But I suppose there’s a remote chance the autoconfig/format just got corrupted.
 
Re: above, reading the manual more carefully there isn’t a specific “user defined” jumper, the formatter program asks you if you want to use the jumper defaults or enter your own parameters. So, again, if the drive has a valid format by this controller there should be no BIOS shenanigans, it will just work. If it’s not, well, chances are very good it’s dead.
 
Last edited:
Many thanks! Yeah I think my main problem may be the controller.. I have a known good MFM Seagate and we are getting same issue. I'm wondering if the controller bios should be popping up onscreen at post, same as how the ega card bios does.

I suppose the setup is a bit odd.. the BC286 is basically the same computer as the 8088 powered BC88.. just a different CPU card. Apparently Computerland thought being easily able to swap cpu for an upgrade was the ticket.

So you're thinking I shouldn't need to touch the system bios at all then?

I will try doing the debug sequence on the controller just to see what it does. If the card is dead that sequence probably won't work.
 
Admittedly my experience isn't that broad but I can't remember ever seeing an XT MFM hard disk controller that stuck a message on the screen unless there was a problem. (In which case it'd be something terse like a 1701 error.) One that puts out a splash like an EGA card would be a new one on me.

My guess is the controller is fine and the hard disk it came with is dead. Swapping in a known good HD is still going to produce errors until you format it with the controller's BIOS, it's very rare to be able to move MFM disks between different types of controllers without reformatting.
 
You must log in or register to reply here.
Back
Top