Modifications to my IBM5155 & 5160

[Minerva10210]

Howdy guys

So I was fiddling with my old machines over the weekend - cleaned them all up properly, stripped everything to the bare chassis used a paintbrush to clean everything and some soap on the chassis covers etc.

Now I have a few different ideas here of what I can do with the machines. I would like your guys' input here though.

Now before I note the mods I would like to do, I don't want to do any physical modifications to the machines in such a way that would make it impossible to get the machines back to OEM standards.

First thing I was thinking of doing is to put a vanilla 386 motherboard in the 5155. I would like to be able run win311 on the machine. The issue here is that the CGA (I think ) graphics card in the 5155 is obviously a 8-bit card, but it has an "overhang" that makes it impossible to install this card in a 16-bit slot. Now looking at the card in the 5160, it does not have the overhang, so it will fit. Now the issue with going this route, I am not too sure if the internal monitor will work off the card in the 5160.

On the 5155 card, there is a 4-pin connector (pin 3 blanked) that connects to the monitor internally. On the 5160 card there is a 6-pin connector that looks simmilar, but it does not have a blank pin so I am a bit scared of trying to connect the monitor to this. Alternatively, are there any other GFX cards that I could use that will be able to connect to the monitor in the 5155? Any ideas here?

The other idea that I had is to get something like a ST-251 1/2 height HDD to put into the 5155. I can't remember how to configure MFM HDD's though, any resources available that I can read up on?

Then another thing here. The 5155 has a 10MHz AMD based CPU in it, the 5160 has a 4.77MHz Intel based CPU. Is it possible that if I get hold of another 10MHz CPU just to retrofit the CPU, or is it necessary for other changes that have to be made?

Also, is there a real world difference between the 8088 and the 8086? I noted that the 86 has a 16bit bus vs the 88 has a 8bit bus. As I asked does this make a real world difference?

Phew! I think that is all for now!

Thanks guys!

Jonathan
ZA

 

[mbbrutman]

I'd get a copy of the technical reference for the 5155. The motherboard is similar to the 5160, but obviously there are other differences that the tech ref should cover.

The existing CPU might be a 10Mhz AMD part, but are you sure it is not just running at 4.77 anyway? It is a common technique to buy whatever parts are available that meet a minimum standard and use them. You should run an old 'speed tester' program that gives you a speed rating relative to the 5160 to see if it really is running faster than 4.77Mhz.

Assuming it is running at 4.77Mhz, the simplest CPU upgrade you can do is to replace the 8088 variant with a NEC V20. The NEC V20 at the same clock speed is faster than the 8088 for most instruction mixes, and it implements the non-protected mode 80286 instructions. In plain English, that means that you can run some DOS 80286 only software on your machine. And it will be a little faster (5 to 15%) overall.

The 8086 should be quite a bit faster when going to memory. The 16 bit data path really helps. For everything else though, it's not much of a difference - the I/O bus on the machine is still only 8 bit PC bus, not 16 bit ISA.

 

[retrobits]

5155 here also, would like hard drive

5155 here also, would like hard drive

Hi there,

I've got a 5155 also, and would like to have a hard drive. For those who have put a 1/2 height HD in a 5155, what were the challenges? For instance:

Does a 1/2 height HD mount without modifications in the floppy drive bay of the 5155 (assuming you take out the B: drive)?

Is there any issue with the power supply having enough juice for a hard drive? Would it handle, for instance, an ST-251?

What HD controller did you use, and does it have both floppy and HD ports?

How did you fit the controller into the somewhat limited slots of the 5155? In the big slots, I currently have the floppy controller, the CGA card, and an AST SixPakPlus.

Thanks,

- Earl

 

[per]

The issue here is that the CGA (I think ) graphics card in the 5155 is obviously a 8-bit card, but it has an "overhang" that makes it impossible to install this card in a 16-bit slot. Now looking at the card in the 5160, it does not have the overhang, so it will fit. Now the issue with going this route, I am not too sure if the internal monitor will work off the card in the 5160.

Note that many 286 and 386 boars offer one or two 8-bit-only slots to eliminate that problem. When it comes to the internal monitor, you should try to use a CGA card. The signals it runs on is plain NTSC composite in B/W (IIRC), and it's quite standard. There may be EGA cards with composite outputs, but I don't know of any spesific model.

On the 5155 card, there is a 4-pin connector (pin 3 blanked) that connects to the monitor internally. On the 5160 card there is a 6-pin connector that looks simmilar, but it does not have a blank pin so I am a bit scared of trying to connect the monitor to this. Alternatively, are there any other GFX cards that I could use that will be able to connect to the monitor in the 5155? Any ideas here?

Plugging a contact into a connector you are unsure about is quite a bad idea. In the worst cause, you may risk frying some components by giving them too much voltage/worng signals. You don't want that, so you must make completely sure what the connectors are for before you actually plug something into them.

Then another thing here. The 5155 has a 10MHz AMD based CPU in it, the 5160 has a 4.77MHz Intel based CPU. Is it possible that if I get hold of another 10MHz CPU just to retrofit the CPU, or is it necessary for other changes that have to be made?

Getting a faster CPU doesn't automaticly make it run faster, it just allows it to run faster. The speed is determined by a clock on the motherboard, and is divided by 3 to give the 4.77MHz main system clock (used by the CPU and most of the intelligent chips on the motherboard). In order to speed up the CPU, you will have to replace the clock with a faster one, something that is quite a bad idea since there are several other components on the motherboard that can't handle more than 5MHz.

Also, is there a real world difference between the 8088 and the 8086? I noted that the 86 has a 16bit bus vs the 88 has a 8bit bus. As I asked does this make a real world difference?

Yes it does. The system bus in the XT is only designed to have 8 data-bits, and it simply has no way of handeling the upper half 8-bits if a 8086 were used. Because of this, the CPU would only be able to read every second byte. Since most instructions is at least two bytes long, the CPU would be rather useless then.

 

[mikey99]

I added a Seagate ST-225 MFM drive to my 5155. The drive fit into the drive "B" slot after
removing the second floppy. I used a Western Digital short card ...can't recall the exact model
number. The only challenge was modifying the black plate that hides the front of the drive.
I needed to file down two sides to get it to fit in there. I was a bit worried about the power
supply not having enough power to handle the extra drive, but haven't had any issues.
I think a better option would be to use an XT-IDE controller and put in an IDE drive
that will draw less current from the power supply.

Hi there,

I've got a 5155 also, and would like to have a hard drive. For those who have put a 1/2 height HD in a 5155, what were the challenges? For instance:

Does a 1/2 height HD mount without modifications in the floppy drive bay of the 5155 (assuming you take out the B: drive)?

Is there any issue with the power supply having enough juice for a hard drive? Would it handle, for instance, an ST-251?

What HD controller did you use, and does it have both floppy and HD ports?

How did you fit the controller into the somewhat limited slots of the 5155? In the big slots, I currently have the floppy controller, the CGA card, and an AST SixPakPlus.

Thanks,

- Earl

 

[Minerva10210]

Note that many 286 and 386 boars offer one or two 8-bit-only slots to eliminate that problem. When it comes to the internal monitor, you should try to use a CGA card. The signals it runs on is plain NTSC composite in B/W (IIRC), and it's quite standard. There may be EGA cards with composite outputs, but I don't know of any spesific model.

Plugging a contact into a connector you are unsure about is quite a bad idea. In the worst cause, you may risk frying some components by giving them too much voltage/worng signals. You don't want that, so you must make completely sure what the connectors are for before you actually plug something into them.

Getting a faster CPU doesn't automaticly make it run faster, it just allows it to run faster. The speed is determined by a clock on the motherboard, and is divided by 3 to give the 4.77MHz main system clock (used by the CPU and most of the intelligent chips on the motherboard). In order to speed up the CPU, you will have to replace the clock with a faster one, something that is quite a bad idea since there are several other components on the motherboard that can't handle more than 5MHz.

Yes it does. The system bus in the XT is only designed to have 8 data-bits, and it simply has no way of handeling the upper half 8-bits if a 8086 were used. Because of this, the CPU would only be able to read every second byte. Since most instructions is at least two bytes long, the CPU would be rather useless then.

Hi

Great info there thanks!

I'll go point by point again

- 386 mobos. Yes, I have a board or two that do actually have 8bit slots, but the issue is that all the boards I have the 8bit slot is on the right hand side, whereas the 5155 only has space for a full length card on the left side of the board

- The monitor. Yes, I obviously want to make double sure before I go ahead and plug stuff in... Also I may add, I didn't even think of NTSC, as here in SA we run PAL-I. Will have to keep that in mind thanks! I used to own an EGA card with composite out, will have to see if it is still around and will test with it then.

- CPU. Hmmm, here you can see my skill has run out a bit on the XT's - I only actually started fiddling with computers circa 386 and a 286 or two, so my XT experience still needs some working on it... With the 2/3/486 one would just replace the current CPU with a faster unit and set the DIPS/Jumpers appropriately. Obviously not the case with the XT's

- 86 vs 88. Ok, will ten just leave it standard then :D



Then @ mikey99
Yeah, I noticed that on mine as well. It needs to be about 1 - 2mm shorter than a "standard" 5 1/4" drive.

I would like an XT-IDE for sure, but I think due to our local currency exchange rate and postage it might be a bit prohibitive price wise... Will look into it though at a later stage...

 

[southbird]

Not that this helps with your particular setup, but I'll just note that once upon a time, I fitted a Pentium 166MHz board, a 3.5" HDD mounted onto the internal radio screen (those holes work as screw holes pretty well), and had a CD-ROM in one bay and a mounted 3.5" floppy in the other. Used a VGA with a TV-Out port to route into the internal display, which mostly worked (it did seem to have a bit of a problem with high contrast, but that might have been some kind of interference.) Played Duke Nukem 3D in shades of amber...

 

[Minerva10210]

Not that this helps with your particular setup, but I'll just note that once upon a time, I fitted a Pentium 166MHz board, a 3.5" HDD mounted onto the internal radio screen (those holes work as screw holes pretty well), and had a CD-ROM in one bay and a mounted 3.5" floppy in the other. Used a VGA with a TV-Out port to route into the internal display, which mostly worked (it did seem to have a bit of a problem with high contrast, but that might have been some kind of interference.) Played Duke Nukem 3D in shades of amber...

HAHA, nice one, Duke3d in amber :D

So this project of mine has been on hold for a while. I had a shortage of parts :|
I am going to my parent's place tomorrow and will rummage through my old man's garage, hopefully my old stuff is still laying around there and is still in working condition.
When I tried doing some mods I noted that I don't have any of the following here -->

- 30 or 72 pin RAM
- Any ISA (8 or 16 bit) controllers or video cards
- coolers for a 486
- Any MFM/RLL drives

So I could not do any mods to tha machine :?

Will update as soom as I have some old parts :D

 

[Minerva10210]

Hi all

I've been incredibly busy at work recently so my vintage computing has taken the back seat for a while

OK, so as things are standing, I have changed my mind about the IBM Machines that I have.
What I did do, is to test all my 286 & 386 boards to replace the XT in the Portable. I was not thinking too hard though, I forgot that the XT keyboard will not work with an AT machine :blush: So what I was thinking is to check all the XT boards that I have and see if I have a "turbo" version hanging around anywhere. Also, I came across an ST225 HDD and 2 WDXT Gen2 controllers. I am thinking of replacing the B: drive with the HDD, otherwise if I can get the XTIDE card up and running that I purchased from Lynchaj, maybe put a 32MB SD card in there. Now the questions -->

Is there an easy way of checking is a XT mobo is indeed a turbo 8/10MHz version?
Will the default expansion cards out of the 5155 and the WDXTGen2 work in the machine?
From what I've read about the XTIDE, it will work in any machine right?
Then on the WDXTGen2, I have gotten hold of some documentation for the card, will fiddle with it a bit, but when you "initialise" the drive using the debug commands, this only configures the card to access the drive correct? much like auto-detection in later BIOS' correct? That means that I would still need some or another partitioning/format tool to be able to use the drive? I used to have DiskManager on a floppy somewhere, but can't find it at the moment

Now as I stated earlier in the thread, I will be keeping all the original parts for the machine to get it back to "factory defaults" if needed.

OK, think that's it for the moment, your comments please!

 

[gerrydoire]

I have an IBM 5155 but I enhanced it while it remains mostly intact as it was from the factory.

I put in the best 8 bit cards available for it, most of them new or near new, ATI Graphics Solutions, Acculogic IDE Card, 286 Card that gives me both 286 and the original
8088 speed etc etc.

The computer has both IBM floppies in front.

Once you remove the original motherboard, its no longer an IBM 5155, but a "whatever" in an IBM 5155 Case..

The IDE card inside has a 128meg and 512meg CF Cards attached, gota love it!!

I wanted to push the computer to the limit with stuff that was made in its era to do so, the only thing that is truly modern, is the CF cards which just happen to work
with the 20+ year old 8 bit IDE Card.

If I could get an Intel Inboard 386 card for it, that would be the max, I think...

 

[ibmapc]

I put in the best 8 bit cards available for it, most of them new or near new, ATI Graphics Solutions, Acculogic IDE Card, 286 Card that gives me both 286 and the original
8088 speed etc etc.

I'm curious about your "286 card". What is the brand and model #? I attempted to use a card in my 5155 years ago which I believe was call "Tiny Turbo 286" but don't recall the manufactuter. I ended up returning it due to the fact that the 5155's power supply was not up to the task and it would cause the machine to reboot durring graphic intensive operations. Since I could not find an easy way to upgrade the power supply, the 286 board had to go away.

 

[gerrydoire]

I'm using the Tiny Turbo 286, but all the other cards are short length not full length, maybe they consume less power?

I've never really ran much on the thing except mediocre programs and a few old Sierra Games, seems to work fine,
also, my 5155 doesn't have a physcial hard drive from the good old days running, just low power CF cards, so
perhaps that made the difference?

 

[ibmapc]

I'm using the Tiny Turbo 286, but all the other cards are short length not full length, maybe they consume less power?

I've never really ran much on the thing except mediocre programs and a few old Sierra Games, seems to work fine,
also, my 5155 doesn't have a physcial hard drive from the good old days running, just low power CF cards, so
perhaps that made the difference?

Sounds like I might have ditched the "Tiny Turbo 286" prematurely. Call to Orchid Tech Support at the time revealed that the weak power supply was the problem with no work around. I'm thinking the stock CGA Card in combo with the "Tiny Turbo" may have been to much of a power drain. Gerrydoire say's he has an "ATI Graphics Solutions", which I'm guessing is more efficient than the Stock CGA. By the way, The random reset occured while running MS Flight Simulator 1.0 from floppy. I didn't have a hard drive in the unit at that time.

 

[gerrydoire]

Could of been an incompatibility with the game and the Tiny Turbo Card, but without extensive testing, I can't be sure.

One thing i've noticed about this tiny turbo, the 286 chip gets extremely hot.

 

[Minerva10210]

Wow, the tiny286 thing sounds sweet!

N that train of thought, I have a few Rampage286 Cards haning around too. I am guessing they will not work in a XT? the cards are 16bit isa and obviously marked as "286"

Can't wait for the weekend though, going to fiddle with the 5155 then.

Anyone have any feedback on my other questions earlier in the thread?

 

[strollin]

Instead of trying to shoehorn a 386 motherboard into a 5155 you might want to see if you can get hold of an IBM P70 386. These came with either 16 or 20 Mhz 386 already as well as a hard drive. Of course they are a PS/2 so use microchannel but they are essentially a little more modern 5155.

 

[Minerva10210]

Yeah, like I said, I'm going to leave it be as an XT...

Just want to beef it up a bit

 

[Minerva10210]

OK, an update for you guys!

I have now fitted the WDXT-GEN2 controller card to the machine with a Seagate ST225 drive. I am busy using the built-in low level format utility to format the drive. It has been busy for approx 3 hours now. It does sound like it is doing something, whether it is doing it right, I am unsure :? I can notice a difference in the sound of the drive, in the beginning I could hear the stepper going for short bursts which has become longer and longer, so I take it is tracking across the drive - it makes sense to me at least, but like I said, I dont know if it is doing the right thing here :|

I did notice something REALLY sad though... I only noticed this evening when I powered up the machine a few times that it is running a DTK motherboard and not an IBM board. which obviously makes the machine no longer authentic. Ah well, it goes that way I suppose.

Anyway, while I am waiting for the format, I came across another 5.25" floppy drive which I am going to test in my main PC now, hopefully I can then transfer something like laplink to the machine so that I can start populating the HDD with some "useful" software :D

Will keep you guys updated about my progress!

Cheers
Jonathan

 

[Minerva10210]

ARGH!

Ok, so after waiting 4 hours, it would seem that I did not get anywhere

I tried both IBMDOS 2.10 and ACERDOS 3.20, and in both cases when I run fdisk, it gives me an error message "error reading fixed disk"

These are the only versions of DOS I have available to me at the moment, could it be that these early versions just don't read the drive properly, or did I not do something I was supposed to?
This is making me feel like a serious n00b, and frustrating as hell :x

 

[modem7]

Ok, so after waiting 4 hours, it would seem that I did not get anywhere
I tried both IBMDOS 2.10 and ACERDOS 3.20, and in both cases when I run fdisk, it gives me an error message "error reading fixed disk"

One of the causes of FDISK's "error reading fixed disk" is that the drive isn't low-level formated (via the connected controller).

The low-level format of an ST-225 takes about 5 minutes. During the low-level format, there is a single step about every half second. Obviously, something is going very wrong for you.

Whilst you could have a bad ST-225, there are other things to consider first. One thing is the connection of the two cables (control and data).

I know that with an XT-GEN/ST-225 combination, one cause of the symptom of short bursts of quick steps during a low-level format, is an incorrectly connected data cable (the 20 pin cable). On the XT-GEN2, ensure that the data cable is plugged into J2, not J3. Also, check that pin 1 of cable goes to pin 1 of J2, and to pin 1 on the drive.

Is the data cable correctly connected?