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IBM 5160 XT and XT-CF detection issue

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paperinik77pk

Member
Joined
Jan 7, 2016
Messages
33
Location
Arese (Milan), Italy
Hi all,

I just completed to restore an IBM 5160 XT, repairing the motherboard, cleaning the floppy drive, putting a 130W power supply and fitting all original IBM cards in it.

It started as a 068 model (256kb, MDA, one 360k FDD and IBM 5151) and has been modified to be a 086 submodel (256kb, CGA, one 360k FDD and IBM 5153, plus the Original ST412 disk i got in the meantime). MDA and 5151 will be part of my 5150 project in the future.

The ST412 disk NEVER worked, I found it in a flea market and it is aesthetically nice. I've the original Xebec controller, but since the disk is not turning at all, obviously I cannot get it to work.

So I kept the front panel of the ST412 and I thought to add an XT-CF (assembled by Pearce, rev2 - smallest version), connecting the panel led to the led connector on the board just to keep the "original" HDD blinking light).

XT-CF works fine on my Olivetti M24, it is fitted with a 16MB CF (fdisked to 10MB as the ST412), it is updated to R580 Bios...but...

...the XT does not detectit at all during POST. It performs the floppy seek, then it goes straight to Basic.
I was expecting the XTIDE menu as usual...but NOTHING. I removed all cards keeping CGA card only.

I tried to boot a floppy with xtidecfg.com in order to see if bios can be loaded by eeprom. NOTHING again.
I changed the starting address flashing an already modified bios (567 - CC00h), I tried to modify the I/O port from 300 to 280/290/310/320/330...no results.

At this point I'm beginning to get a bit confused.

I searched a bit on Internet, on this forum...but it seems the main issues happen when the XT-IDE bios is already detected (MBR - conflicting addresses and so on)

Dou you have some suggestions (even a link to an existing thread, so we can close this one)?
Thank you in advance!

Davide
 
You can not use XTIDECFG.COM to flash the EEPROM on the Lo-Tech cards, Use XTIDECFG.COM to configure and save the bios, Then use the lo-tech flash utility to flash the EEPROM, See this page for info and the FAQ linked to at the bottom of the page.
 
After a few trials, I noticed that in Sysinfo 6.0 the extra rom at C800h is not detected at all.
The same XT-CF card, with the very same setting...is found and shown in Sysinfo on other 8088/V20 machines I have.

My BIOS revision is Nov'82.

I'm beginning to think the scan is not correctly performed by the machine itself.
Could some (broken) electrical component or chip be responsible of the scan failure?

It seems strange also to me since CGA adapter ,Parallel, and Async card are correctly working.
Thank you!
Davide
 
Last edited:
Have you tried the xebec controller to see if its BIOS detected?

paperinik77pk said:
After a few trials, I noticed that in Sysinfo 6.0 the extra rom at C800h is not detected at all.
The same XT-CF card, with the very same setting...is found and shown in Sysinfo on other 8088/V20 machines I have.

My BIOS revision is Nov'82.

I'm beginning to think the scan is not correctly performed by the machine itself.
Could some (broken) electrical component or chip be responsible of the scan failure?

It seems strange also to me since CGA adapter ,Parallel, and Async card are correctly working.
Thank you!
Davide
Click to expand...
 
you can do your own ROM scan using debug.exe too.
After starting debug.exe, at the - prompt, type:
d c800:0

and the block of data debug spits out should start with 55 AA - that's the ROM signature that tells the mainboard BIOS something is there to execute.

If you see only 00's or FF's or perhaps random data, then the ROM is not decoding at C800. A screen capture of the output may be useful.
 
Do you still have the original hard drive controller installed?

Didn't some xt drive controllers use the C800 address? Maybe you're seeing a conflict.

*edit* Ah, never mind, you're trying with ONLY the CGA card installed. */edit*
 
Should work in slot 8, That is of course it has all the SMT components fitted and is set up properly, Did you buy the card assembled from Lo-Tech or someone else on ebah.
 
Hi all, first of all thank you for your help. I'm a newbie on debug and I'm not so smart with all hex, bynaries and so on. But I like to understand how things work...so I use a trial and error approach, at least for now :)

So...right now the 5160 is opened and ready for action. Floppy drive controller installed in order to have debug command available, and CGA.
No XT-CF installed at the moment.

DEBUG
-d c800:0

well...it seems something is already there...
C800:0000 02 34 01 A2 FC 02...

So I've tried the other common XT-CF address D800:
D800:0000 02 34 01 A2 FC 02

...the same from the beginning to the end (is it normal?)

At CC00 (I saw a BIOS set at this segment - maybe R566?) I have other numbers
CC00:0000 56 69 6A...

Also CA00 is full.

At this point...ok, it seems the XT-CF is not detected because there is something else where its BIOS usually starts.

So, back at documentation - I started from this XT5160 memory map:
http://www.minuszerodegrees.net/5160/misc/5160 - Memory Map of the 640 KB to 1 MB Area.jpg

I tried to find other free(?) places...like E0000, D0000 and F0000 (all filled with E8 E8 E8 E8...)
From what I see on the monitor they are to be filled with $$$$$$ - I do not know if it is a kind of initialization value.

Maybe pointing The XT-CF bios to E000 could be a good trial?
:D:D:D
 
Malc said:
Should work in slot 8, That is of course it has all the SMT components fitted and is set up properly, Did you buy the card assembled from Lo-Tech or someone else on ebah.
Click to expand...

I both have an original James Pearce XT-CF and other 3 cards bought on Ebay.
JP card has all components for slot 8, the other one does not provide slot 8 compatibility.
By the way, even with JP card on slot 8 - no detection at all. Now JP card lives inside my M24.

Since I have an original ASYNC board, I use it inside slot 8 (properly jumpered as manual suggests).
:D
 
paperinik77pk said:
At CC00 (I saw a BIOS set at this segment - maybe R566?) I have other numbers
CC00:0000 56 69 6A...
Click to expand...
A BIOS expansion ROM looks like what is pictured in the diagram at [here]. The first two bytes are 55h then AAh. Then is the size byte. After that, the content varies from BIOS expansion ROM to BIOS expansion ROM.
 
paperinik77pk said:
I tried to find other free(?) places...like E0000, D0000 and F0000 (all filled with E8 E8 E8 E8...)
Click to expand...
I think that E8 E8 E8 E8... covering large area is a good indicator of 'no RAM at these addresses'. With my 5160 motherboards, one reads back FC at an unused address, another reads back FE, and another reads back FF.

paperinik77pk said:
From what I see on the monitor they are to be filled with $$$$$$ - I do not know if it is a kind of initialization value.
Click to expand...
The power-on self test of the 5160 does not set anything in the Upper Memory Area to a particular default value.
 
modem7 said:
A BIOS expansion ROM looks like what is pictured in the diagram at [here]. The first two bytes are 55h then AAh. Then is the size byte. After that, the content varies from BIOS expansion ROM to BIOS expansion ROM.
Click to expand...

Exactly the picture I was trying to find (I read it some days ago and I could not find it anymore)!
On my Olivetti PC1, the debug command at C800:0 (with the same XT-CF card I'd like to use on 5160XT) shows 55 AA 10 E9...and to the right side I can find a quite clear "XTIDE BIOS 2.0.0b3..." so it is how it the card works on an XT(well, sort of) where it is properly detected.

On XT5160, the C800:0000 segment is "dirty" even without any expansion cards fitted, so something is using it.
I removed the floppy card and I mounted the XT-CF. No way (tried C800 and D800). So the last suspect is the CGA? It should start under C000:0 so it seems very strange to me.
 
modem7 said:
I think that E8 E8 E8 E8... covering large area is a good indicator of 'no RAM at these addresses'. With my 5160 motherboards, one reads back FC at an unused address, another reads back FE, and another reads back FF.


The power-on self test of the 5160 does not set anything in the Upper Memory Area to a particular default value.
Click to expand...

Ok, so D000 could be a good candidate.
Is there any tool I can use to prepare an XTIDE bios rom to point that specific address - or maybe an already prepared bios binary I could use? :rolleyes:
 
paperinik77pk said:
Ok, so D000 could be a good candidate.
Is there any tool I can use to prepare an XTIDE bios rom to point that specific address - or maybe an already prepared bios binary I could use? :rolleyes:
Click to expand...

There was a Tandy 1000SL or RL custom version that was offset in the ROM image and showed up at D000...

Have you checked with Norton SYsinfo? It'll show you installed roms and addresses...

Ah here it is.

https://www.lo-tech.co.uk/downloads/XT-IDE/lo-tech-isa-compactflash-adapter/offr566.zip

It's offset at CC00h, check if you have ROM data there with debug.
 
Can you post a good Photo of the actual card you are trying to get working, Solder side and Component side. There has been a few people selling these cards on ebah in the past and i remember one seller was selling an old revision of the card, The older revision was fixed at Rom address C800 and the later cards are configurable C800 or D800 Rom address, Though to use D800, A SMT resistor must be fitted IIRC.
 
paperinik77pk said:
Is there any tool I can use to prepare an XTIDE bios rom to point that specific address - or maybe an already prepared bios binary I could use?
Click to expand...
The XTIDE Universal BIOS is 'portable'. The hosting card controls which address range that the ROM appears at - the XTIDE Universal BIOS adapts automatically.

BTW: The time that XTIDE Universal BIOS does need to be reconfigured, is when the I/O port range at which the IDE interface sits at, has been changed.

paperinik77pk said:
On XT5160, the C800:0000 segment is "dirty" even without any expansion cards fitted, so something is using it.
I removed the floppy card and I mounted the XT-CF. No way (tried C800 and D800). So the last suspect is the CGA? It should start under C000:0 so it seems very strange to me.
Click to expand...
CGA should be going nowhere near C8000. (Some VGA cards do extend into the C8000 area.)
If you are curious, post us a photo of the DEBUG screen. That may help us identify the source.

But it sounds like D0000 is what you should be aiming for (if the card can be reconfigured for that).
 
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