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lutiana
May 9th, 2011, 02:45 AM
So I grabbed 3 of these systems and was a little bit dissapointed to find out that they were the 8086 versions not the 286 versions. I am playing around with one and I have some questions:

1. First off, how can I tell if the drive in the system is a 720k drive or a 1.44mb drive? 2 of the machines have drives with a silver top cover and 1 has a drive with a black top cover.

2. Then, how does one actually remove the drives?

3. On the mainboard there is a connector behind the floppy connector, and as near as I could find out it is for a HDD, this system has an MFM hard drive connected to an ISA card, so it does not use the built in controller. My question is what type of HDD would use the MB connector? Is it IDE?

4. Most references out there say the machine has a max of 640kb RAM, yet the MB has 2 30pin RAM sockets (both full) and when I run the IBM setup utility (that was on the HDD) it tells me the system has 14mb of RAM installed (but the BIOS screen only counts out 640kb). So what gives here? I assume the software is wrong, but then why does it have the simms sockets?

5. Anyone know what voltage battery this thing needs? All three have batteries that read out at around 3v

6. All the references out there say this machine should have an MCGA Gpu, yet all 3 have VGA GPUs, any idea why there this is?

7. Any one got a link handy for the setup disk I need to setup the BIOS on the 2 machines that somehow got reset?

8. I notice in most of the pictures that the on switch is white, but all three of mine it is red. Does the red mean it is an 8086 and the white a 286? If so I am going to kick myself since there were a few that I could have grabbed that had the white button.

I am sure I will have more questions, but this will help me get started :D

lutiana
May 9th, 2011, 02:50 AM
Never mind about number 4. I pulled them out and realized that they are each 256k chips, that bring the system up to 640k. Does anyone if you can boost that a bit or not? I'd assume not, but it does not hurt to ask.

kishy
May 9th, 2011, 06:27 AM
RE: removal of drives, the front bezel faceplate comes off (notice at the top of the faceplate, there are two visible gaps...lever in a small screwdriver...do this carefully or the clips may break. It has latches at the top and is hooked onto the bottom, so first you release the top, then pull upwards to get it off of the bottom) and the drive (which is mounted on a 'sled') slides out the front of the machine after you release a latch.

I believe drives that do not have writing on their button are 720K, while 1.44s say '1.44' and 2.88s say '2.88' (you very likely have 720s)

The onboard hard drive interface, despite what some have said before, is in fact proprietary...it appears to have never been used anywhere except in the PS/2 Model 25 and 30. It is not the same as DBA ESDI in some other PS/2s, as that is actually MCA, and it is not a simple re-connectorization of a more standard 'MFM' hard drive interface (although adaptation to this MIGHT be possible with some hacks - this hasn't been confirmed either way, yet, to the best of my knowledge, and the setup disk will not offer options outside of the original HDD specs anyway). There are only two or three models of drive that will connect to this interface, and I've read things that suggest they were especially failure-prone drives...meaning the chance of finding one is probably slim, and finding one working is even less likely.

So, I would advise doing what I do...pop in some other interface card (XT-IDE, SCSI if available, or stick with the ST412-type controller if you like using the old drives - I do not, as they seem to drop dead left and right around me) and if needed, make a little cable to draw the power out of the proprietary HDD interface connector.

5692

Enjoy your new toys, and welcome to the funky world of PS/2s that tried to be like XTs!

lutiana
May 9th, 2011, 07:04 AM
So, I would advise doing what I do...pop in some other interface card (XT-IDE, SCSI if available, or stick with the ST412-type controller if you like using the old drives - I do not, as they seem to drop dead left and right around me) and if needed, make a little cable to draw the power out of the proprietary HDD interface connector.


No need, each one has a fully functional MFM drive in it. ST124 in 2 of them and a WD something in the other.

I did finally manage to work out to get the drive out, and you are correct all three are 720kb drives, which means I am dead in the water till I can get some 720k media.

RetroHacker_
May 9th, 2011, 07:12 AM
I did finally manage to work out to get the drive out, and you are correct all three are 720kb drives, which means I am dead in the water till I can get some 720k media.

You can cheat and tape over the density sense hole on a high density disk and reformat for 720k. It usually works OK, and seems to work best if the disk is new. Might not be 100% reliable, but good enough for transferring stuff.

Or, if you want some disks and can't find any, let me know, I've got some new 50 packs of DS/DD 3 1/2" floppies I could probably sell.

-Ian

lutiana
May 9th, 2011, 07:15 AM
You can cheat and tape over the density sense hole on a high density disk and reformat for 720k. It usually works OK, and seems to work best if the disk is new. Might not be 100% reliable, but good enough for transferring stuff.


Yeah, I tried that with no luck. I managed to format it as a 720k in my Win98 machine, but whenever I tried to access it explorer would crash. I was able to write to the 720k formatted disk in my Win7 machine, but then the disk became corrupted.

I'll try it again later with a newer disk, but I may just try to hack in a 1.44mb drive.

IBMMuseum
May 9th, 2011, 07:32 AM
Never mind about number 4. I pulled them out and realized that they are each 256k chips, that bring the system up to 640k. Does anyone if you can boost that a bit or not? I'd assume not, but it does not hurt to ask.

The SIMMs are 256Kb each, giving 512Kb for the pair. Initially many Model 25s had just the SIMMs, and the additional 128Kb to get to 640Kb on the planar (the DIP sockets close to the BIOS chip) was an optional kit. Later releases (especially with a color CRT) seemed to have the full 640Kb.

It isn't uncommon on the 8086-based Model 25 to find an HDD adapter installed with a 3-1/2 MFM drive, and the proprietary HDD interface on the planar unused. IBM released large blocks of serial numbers this way. Lewis Eggebrecht (lead of the IBM PC design team) only listed that type in his book describing the early PS/2s.

The 8086-based Model 25 (and 30) came with 720Kb drives stock. 1.44Mb drives on these systems weren't an option from IBM, and the upgrade wasn't even discussed in their references. Later work by hobbyists figured out in most cases the 1.44Mb IBM drives were a drop-in replacement on the Model 25, and a specific Sony-sourced 1.44Mb drive would work on the Model 30.

Unlabeled, generally "big button", eject buttons are 720Kb...

Does your Model 25 have an "edge" (40 contacts) or "pin" (34 contacts) for the drive interface?...

Removing the drives is somewhat a PITA...

There should be no battery, as that particular model of PS/2 was the only one without an RTC. Your "VGA, not MCGA" comment confuses me (meaning another adapter connected to the internal video?). There is no "Reference Diskette" for the ISA PS/2s (it is referred to as a "Starter Diskette"), and the Model 25 has no "setup" utility as one is not needed.

The "red toggle" can signify a lower-end model, lower-wattage unit, or an earlier release. In some cases (across the PS/2 line) it can mean nothing. I'm not sure on the Model 25 if it meant a difference in units.

http://walshcomptech.com/ps2/m25stuf.htm

lutiana
May 9th, 2011, 09:02 AM
Does your Model 25 have an "edge" (40 contacts) or "pin" (34 contacts) for the drive interface?...


I believe my units are model 30, they look like this (http://mastodonpc.tripod.com/personal/images/8530-h31.jpg), just with a red switch (and no where near as clean). The HDD has 2 edge connectors I believe, looks like MFM to me, one cable is wider than the other.



There should be no battery, as that particular model of PS/2 was the only one without an RTC. Your "VGA, not MCGA" comment confuses me (meaning another adapter connected to the internal video?).


Yep, all three have a battery in them and they test out at 3v. The battery is on the ISA riser card towards the front of the machine. Do you mean the model 25 has no RTC?

The onboard video on my units is VGA, but all the reference I could find on this model say that the 8086 Model 30 units shipped with MCGA (though they don't specify if it was on board or not). Ahh the wiki article (http://en.wikipedia.org/wiki/IBM_Multicolor_Graphics_Adapter) on MCGA explains it, MCGA is basically VGA without EGA support, which is why it works with my LCD and I mistook the connector for a VGA one.



The "red toggle" can signify a lower-end model, lower-wattage unit, or an earlier release. In some cases (across the PS/2 line) it can mean nothing. I'm not sure on the Model 25 if it meant a difference in units.
http://walshcomptech.com/ps2/m25stuf.htm

Mine are model 30 units. I'll post some pictures later.

IBMMuseum
May 9th, 2011, 11:29 AM
...Mine are model 30 units...

I don't know why I headed down the Model 25 path, but it is a Monday I guess...

Scratch much of my post, I should re-edit it...

Maverick1978
May 9th, 2011, 01:25 PM
More hauls from the giveaway? :)

I've a Model 30 286... Nice system. From my understanding, the Model 30 XT's were similar to the Model 25 - I've never actually seen pix of these. Looking forward to them..

BTW. If you're looking to let loose of a working hard drive for these models, let me know - I'd be interested in replacing my dead 20mb in my Model 25 (I plan to put in an XT-IDE, but like to keep the machines original as well)

Dave Farquhar
May 9th, 2011, 01:49 PM
From my understanding, the Model 30 XT's were similar to the Model 25 - I've never actually seen pix of these. Looking forward to them..

I haven't had a Model 25 open since 1992 or 1993, and haven't had an 8086-based Model 30 open since 1995 or 1996, but my recollection is that they were similar. The Model 25 didn't have as much room in it, being a compact, all-in-one system, but that was the primary difference. If you wanted something that took as little space as possible, you got a Model 25. If you wanted more expandability, you bought a Model 30. So the schools I attended (and ended up doing tech work for) got Model 25s for their labs, and Model 30s to put in offices.

kishy
May 9th, 2011, 03:36 PM
I haven't had a Model 25 open since 1992 or 1993, and haven't had an 8086-based Model 30 open since 1995 or 1996, but my recollection is that they were similar. The Model 25 didn't have as much room in it, being a compact, all-in-one system, but that was the primary difference. If you wanted something that took as little space as possible, you got a Model 25. If you wanted more expandability, you bought a Model 30. So the schools I attended (and ended up doing tech work for) got Model 25s for their labs, and Model 30s to put in offices.

Refer to my signature for lots of pics of the insides of a Model 25 and a Model 30 286...

sergey
May 11th, 2011, 03:27 PM
Yeah, I tried that with no luck. I managed to format it as a 720k in my Win98 machine, but whenever I tried to access it explorer would crash. I was able to write to the 720k formatted disk in my Win7 machine, but then the disk became corrupted.

I'll try it again later with a newer disk, but I may just try to hack in a 1.44mb drive.

1. Make sure you've covered the "high density" hole (not the write protection one).
2. Use the following command to format the floppy, it should work on any version of Windows or DOS (version 3+):
FORMAT A: /T:80 /N:9

Works for me on Win XP, even with previously used floppies...

kishy
May 11th, 2011, 08:05 PM
With regards to floppies, you should take note of the fact that the 720k half-height (so, full height of the drive bay) drives are apparently notorious for failure (mine is certainly dead, and it is not an isolated case as searching suggests)...sometimes it's as simple as some PCB components being replaced, other times the heads have been physically damaged due to poor design allowing them to come into contact with the disk during insertion/removal.

So, if you have difficulties, they may be dead...and if they work, be very gentle with them.

lutiana
May 15th, 2011, 10:40 PM
Apparently all 3 of my 720kb drives are in fact bad. I get sector not found errors when I try to access disks, and if I try to format them I get sector 0 bad errors. The disk is good, I was able to format to 720kb just fine in my Windows 98 machine, and write data to it and read it back on my modern machine.

So I am stuck at the "how do I get data onto the machine" phase.

Is it possible to create a cable that would allow me to use a standard floppy drive?

PeterNY
May 16th, 2011, 05:03 AM
Picture of a Model 30 that I was hoping to purchase off eBay. Unfortunately I forgot about raising my bid.

http://i.ebayimg.com/00/$(KGrHqJ,!mIE2EW0cs8OBNwKVtjk2g~~0_3.JPG

I bought a model 30 286 for $ 10 the other week. :eek:

PeterNY
May 16th, 2011, 05:07 AM
Apparently all 3 of my 720kb drives are in fact bad.

The floppy drive in my Model 30 286 is dead as well. I transfer files to it through FX (e.g. Laplink). I copied FX accross using INTRSVR and INTERLNK. Mind you: the ESDI drive that came with it had MS DOS 6.22 on it already.

PeterNY
May 16th, 2011, 05:09 AM
So I am stuck at the "how do I get data onto the machine" phase.

Is it possible to create a cable that would allow me to use a standard floppy drive?

How about disabling the onboard floppy controller and connecting an 8 BIT ISA I/O controller with a regular FDD? Would that work? I have no idea.

I bought the Model 30 286 to play Wings of Fury and other DOS games that do not run on anything faster. :D So I have no interest in sinking money into repairing the FDD. There are 2 listed on eBay but they might not even work: http://cgi.ebay.com/220782718892, http://cgi.ebay.com/330564097313. Plus they are very expensive (when including shipping).

kishy
May 16th, 2011, 07:20 AM
Apparently all 3 of my 720kb drives are in fact bad. I get sector not found errors when I try to access disks, and if I try to format them I get sector 0 bad errors. The disk is good, I was able to format to 720kb just fine in my Windows 98 machine, and write data to it and read it back on my modern machine.

So I am stuck at the "how do I get data onto the machine" phase.

Is it possible to create a cable that would allow me to use a standard floppy drive?

It should be possible. Late late late one night in IRC myself and someone else were trying to figure that out...some of those findings went into a reply in this thread (http://www.vintage-computer.com/vcforum/showthread.php?24900-So-I-got-a-PS-2-Model-25).

Not a good idea to stick a normal drive on that cable because of the power lines, but this probably goes without saying?

Though, it's been pointed out on these forums that the Model 25 is more flexible in that area, and the Model 30 is much more strict about what will play nice on that connector...so you may be stuck, I'm not sure.

With an XT-IDE you can always pop the drive in another machine and get it all set up there (which is what I did with my Model 25 - MS-DOS, ethernet card packet driver, MTCP...then do all further transfers by running the FTP server on the Model 25. It really is a great arrangement.


How about disabling the onboard floppy controller and connecting an 8 BIT ISA I/O controller with a regular FDD? Would that work? I have no idea.

I've briefly toyed with this on my Model 30 286; there doesn't appear to be a facility to disable the onboard floppy disk controller, and so any add-in card will conflict.

PeterNY
May 16th, 2011, 09:21 AM
I've briefly toyed with this on my Model 30 286; there doesn't appear to be a facility to disable the onboard floppy disk controller, and so any add-in card will conflict.

Right. Well: I will need to stick with FX.

kishy
May 16th, 2011, 09:53 AM
That is not to say, of course, that it isn't possible to disable the controller...but the setup disk doesn't seem to provide an option to, and disconnecting the drive didn't seem to (just gave floppy errors), and there is no jumper for that purpose. Would probably involve adding in a jumper of some kind somewhere...

lutiana
May 16th, 2011, 12:26 PM
Mind you: the ESDI drive that came with it had MS DOS 6.22 on it already.

My drive has some of DOS 6.22 on it, but not interlnk or the mode command, so laplink is not an option yet. Plus the other 2 units I have need the setup disk run on then, which I can't do without a disk drive.

I may be SOL here.

PeterNY
May 16th, 2011, 01:21 PM
My drive has some of DOS 6.22 on it, but not interlnk or the mode command, so laplink is not an option yet. Plus the other 2 units I have need the setup disk run on then, which I can't do without a disk drive.

I guess the only way to fix this is to get your hands on a working FDD and go from there. :(

PeterNY
June 6th, 2011, 05:58 PM
Today I installed the FDD from a Model 55 SX in my Model 30 286. Seems to work great. :D

RWallmow
June 7th, 2011, 10:48 AM
Cant you copy files back and forth over serial without any extra software ie "copy file.txt com1:" on sending PC and "Copy com1: file.txt" on receiving PC. No need for intrsvr or laplink software. Personally I would cram a NIC in the PC and map a drive to my PC (like I have done on many of my vintage boxes, including my model 25).

DOS lives on!!
June 7th, 2011, 11:38 AM
8. I notice in most of the pictures that the on switch is white, but all three of mine it is red. Does the red mean it is an 8086 and the white a 286? If so I am going to kick myself since there were a few that I could have grabbed that had the white button.
On mine, the 286 model has a white switch and the older one, which I'm assuming is the 8086, has a red switch. It's an easy way to tell the two apart.

IBMMuseum
June 7th, 2011, 12:20 PM
On mine, the 286 model has a white switch and the older one, which I'm assuming is the 8086, has a red switch. It's an easy way to tell the two apart.

Exactly. The PSUs are different (besides wattage) for the planar connections, where the 8086-based unit has a connector very similar to the PC/XT/AT style. The Model 30 286 has the same PSU as the Model 55SX and Model 53SLC2 (with a more miniaturized connector).

Case styles between the Model 30s are different as well, with a plastic top for the 8086-based unit, having a dark band at the base, and metal tops for the 30 286, 55SX, and 53SLC2. The 30 286 and 55SX are almost identical from the front (except for the case badge), and would take a look at the back to see if it is ISA brackets (30 286) or microchannel (55SX). There are two different planars for the 30 286, which are the same as what you will find in a Model 25 286.

PeterNY
June 7th, 2011, 12:43 PM
Case styles between the Model 30s are different as well, with a plastic top for the 8086-based unit, having a dark band at the base, and metal tops for the 30 286, 55SX, and 53SLC2. The 30 286 and 55SX are almost identical from the front (except for the case badge), and would take a look at the back to see if it is ISA brackets (30 286) or microchannel (55SX). There are two different planars for the 30 286, which are the same as what you will find in a Model 25 286.

Correct. :D

PeterNY
June 7th, 2011, 12:44 PM
Cant you copy files back and forth over serial without any extra software ie "copy file.txt com1:" on sending PC and "Copy com1: file.txt" on receiving PC.

Would you use a null modem for that purpose?

modem7
June 8th, 2011, 12:48 AM
Cant you copy files back and forth over serial without any extra software ie "copy file.txt com1:" on sending PC and "Copy com1: file.txt" on receiving PC.
I remember experimenting with this in the 80s when I was new to PCs. Following are some of the things that I remember. It won't be everything, and consider that my memory is not what it used to be. I seem to recall dropping the whole idea because it was unreliable.

* There must be flow control if anything other than small files are to be copied. From memory, this meant that the handshaking lines (e.g. CTS/RTS/DTR/DSR) had to be in place and MODE.COM had to be made to go resident.

* RECEIVE SIDE: If there is 'crud' in the UART's receive buffer at the start of the copy, the generated file will have that 'crud' at the start of it.

* If copying binary files, must use the /B option of COPY command (otherwise transfer terminates at first ^Z character encountered).