IBM 5162 aka XT-286 on EBay

[Chromedome45]

Saw this: http://cgi.ebay.com/Vintage-IBM-516...382?pt=LH_DefaultDomain_2&hash=item20b3e3294e

I know there a few looking for one of these. It's up Northwestern Canada area.

Not my auction!

 

[NeXT]

WOW!
That was fast for someone to catch on to this listing.
There are a few more PC's going up tomorrow and I'll finish off our museum lot with some Compaq Portables.

 

[Raven]

Gah, one finally shows up again and when I'm dirt poor.

I'd love to get one of these..

Worth noting that you said "AT motherboard", it's not quite the same - the XT 286 is special because it has the XT's zero wait state RAM, and is actually faster than the AT proper overall - it's not an AT motherboard.

 

[modem7]

Worth noting that you said "AT motherboard", it's not quite the same - the XT 286 is special because it has the XT's zero wait state RAM, and is actually faster than the AT proper overall - it's not an AT motherboard.

A lot of people when they say, "AT", don't mean IBM 5170 - they mean/imply "AT class". It sounds like you two define "AT" differently.

 

[NeXT]

My bad.
I was going to revise it today and found out someone bought the thing. O_O
Now I gotta find a way to park the heads even though I have no floppy media to boot from or software to park it.

 

[modem7]

Now I gotta find a way to park the heads even though I have no floppy media to boot from or software to park it.

All that needs to happen is for the heads to be moved to the landing zone.

I think a type 13 drive was the standard in the 5162. If that's what you've got in your 5162, the landing zone is cylinder 319.
You can move the heads via the DEBUG program in DOS.

Info: The 403f below corresponds to cylinder 319

At DEBUG's "-" prompt, enter in:

a100
mov ah,c
mov dx,80
mov cx,403f
int 13
int 3
<press ENTER at this point without anything else><DEBUG returns the "-" prompt>
g

 

[per]

All that needs to happen is for the heads to be moved to the landing zone.

I think a type 13 drive was the standard in the 5162. If that's what you've got in your 5162, the landing zone is cylinder 319.
You can move the heads via the DEBUG program in DOS.

Info: The 403f below corresponds to cylinder 319

At DEBUG's "-" prompt, enter in:

a100
mov ah,c
mov dx,80
mov cx,403f
int 13
int 3
<press ENTER at this point without anything else><DEBUG returns the "-" prompt>
g

I rather think it's a better idea to poke the machine-code directly into RAM and run it through BASIC (the original IBM diagnostics does this), due to the lack of a DOS disk.

The machine code is as follows:

B4 0C
BA 80 00
B9 3F 40
CD 13
FA
F4

After this code has run, the hard disk head is parked and the machine halts with interrupts disabled.

 

[per]

Here is the code in Microsoft-BASIC (AKA. Casette-BASIC).

10 a=0
20 d=0
30 def seg=&h2000
40 def usr=&h0000
50 for a=0 to 15
60 read d
70 poke a,d
80 next
90 x=usr(0)
100 data &hb4,&h0c,&hba &h80,&h00,&hb9,&h3f,&h40
110 data &hcd,&h13,&hfa,&hf4,&h90,&h90,&h90,&h90

 

[modem7]

due to the lack of a DOS disk.

NeXT's statement was, "I have no floppy media to boot from or software to park it."
That doesn't exclude the big DOS disk - drive C:

 

[per]

NeXT's statement was, "I have no floppy media to boot from or software to park it."
That doesn't exclude the big DOS disk - drive C:

You got a point there, but then there may be a riks of accessing the drive again after parking the drive heads. I don't know if exiting debug is enough to invoke a disk read...

 

[modem7]

You got a point there, but then there may be a riks of accessing the drive again after parking the drive heads. I don't know if exiting debug is enough to invoke a disk read...

Yes, I didn't anticipate the user going back to the DOS prompt, and the possible disk activity that may result (which may be a read of COMMAND.COM).

 

[Raven]

The standard program for parking disk heads that I'm aware of is "SHIP.COM". I have a copy.. somewhere.. and if you end up needing it I could try to dig it up.

 

[modem7]

The standard program for parking disk heads that I'm aware of is "SHIP.COM". I have a copy.. somewhere.. and if you end up needing it I could try to dig it up.

Thanks, but no. The situation is that NeXT can't get such programs onto the 5162 that he's about to post. For the one-off head parking he needs to do, the code we gave him will suffice.

If your SHIP.COM is in fact SHIPDISK.COM and from the IBM Diagnostics diskette, heed the warning given in the first edition of Mueller's 'Upgrading and Repairing PCs' book:
"Several years ago, IBM issued a warning to its dealers recommending against running SHIPDISK.COM from the DOS prompt. IBM said that a slight chance exists that you can lose data because the program can wipe out track 0 of the disk. The memo indicated that SHIPDISK.COM should only be run from the menu."

 

[NeXT]

We already formatted the drive. :/
There was absolutely no way we could sell the thing with data still on the disk. After it was formatted, I was given the OK to list it, else the drive had to be removed.
I'm assuming you can either drop into cassette BASIC by either waiting for everything to fail to boot or by pressing a key sequence. What is the key sequence?

Edit:

Several years ago, IBM issued a warning to its dealers recommending against running SHIPDISK.COM from the DOS prompt. IBM said that a slight chance exists that you can lose data because the program can wipe out track 0 of the disk. The memo indicated that SHIPDISK.COM should only be run from the menu."

So THAT is why my 5155 lost all its data.....

 

[per]

I'm assuming you can either drop into cassette BASIC by either waiting for everything to fail to boot or by pressing a key sequence. What is the key sequence?

There are no key-combinations on the IBM PCs as of I know, and the only way is to wait for it to fail bootstrap. It should then automaticly enter BASIC.

 

[NeXT]

Which means that so long as the hard drive controller ROM is present, it will continue to try and boot from the hard drive and not bother dropping to ROM.

 

[per]

Which means that so long as the hard drive controller ROM is present, it will continue to try and boot from the hard drive and not bother dropping to ROM.

That depends on the ROM.

Typically it should only try ~5 times before giving up, but there may be deviations.

If the controller in the machine is one of the ones which retry an infinitie number of times, then you can either use a different controller whith a different ROM just when parking the heads, or you have to make a custom ROM which takes over Int 19h after the disk controller's ROM has initialized. The code in this ROM should simply be:

DB 055h,0AAh,10h
CLI
XOR AX,AX
MOV DS,AX
MOV BX,0064h
MOV Word ptr [BX],CS
ADD BX,2
MOV Word ptr [BX],offset routine
STI
RETF

routine:
XOR AX,AX
MOV DS,AX
INT 18h

DB ##h

(## corresponds to a value so that the additive 8-bit checksum of the 8KB ROM returns zero)

This ROM must be placed on an ISA card with an empty ROM-socket, which takes 8KB ROMs (usually 2764/2864) and maps it as a ROM extension at D000 or higher.

 

[NeXT]

Okay, I transplanted the drive and controller into a PC and it dumped me to BASIC so I entered in the code, ran...and that seems to be it. I'm assuming since there is no end the program will run and stay running but the drive will have parked

 

[per]

Okay, I transplanted the drive and controller into a PC and it dumped me to BASIC so I entered in the code, ran...and that seems to be it. I'm assuming since there is no end the program will run and stay running but the drive will have parked

Ok, that should be it. The two last instructions were "clear interrupts" followed by "halt". This actively brick the machine untill reset.

But didn't it enter BASIC on the XT/286, or can the XT/286 be set to not boot to BASIC on bootstrap fail? As of I know, the AT and XT/286 shares quite a lot, but I'm not too familiar with neither of the boot settings for those computers.