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Good morning! Welcome back to the ValorosoIT channel, the channel dedicated to vintage computers and electronics. Today I'm talking to you about my IBM PS/1 model 2011 computer, which however is not the year of production. The production year is 1991. 2011 is the model.
I bought this computer a little less than two years ago, with a black and white monitor. It had no keyboard, no mouse and even had some problems. Over the course of these two years I dedicated myself a bit to other projects, I had also bought the components to fix it. I finally got behind it and now the result is this: everything is finally working!
At this point I would like to talk to you about the technical characteristics of the computer and also the work I carried out. The peculiarity of this computer is the startup screen, the one with the four panes, which is not found in other computers. It's very pretty, I like it a lot.
Now let's turn it off for a moment, so I can show you the inside of the computer and analyze the technical characteristics. There's the keyboard... Where do we put it? Maybe we put it above the monitor temporarily.
So, as you already know if you follow my channel @ValorosoIT, my computers never have screws: they are always all basically open and so it takes very little to get involved. Well, one thing I wanted to show you is that the production date of this computer (October 7, 1991) is stamped on the inside of the upper part of the case that I just removed.
Normally, when I do work on the computer, I always keep the components I use aside. For example, these are the ROMs I took out and reprogrammed in English. These were in Italian, because the computer worked in Italian, but I preferred to have them in English. You know that I also have the Instagram channel and the TikTok channel, and I make the videos in English there. I like to show computers that start up with the startup screen in English, so I also wanted to have this computer's screen in English.
The computer is equipped with an Intel 286 processor, a 16-bit processor running at 10 MHz. The RAM is 1 MB, it has 30 MB of hard disk and the graphics card is a VGA. It works at 640x480 pixels with 16 colors or 320x200 pixels with 256 colors.
The nice thing about this computer is that it doesn't have a power supply: it takes the power supply voltage from the monitor. In fact, two cables run from the monitor to the computer: one is the VGA video signal and the other is the 36V power supply. The monitor supplies this voltage to the computer, and then via an internal power supply the voltages of 5V, 12V, etc., necessary for the computer to operate, are generated.
The floppy disk drive is the classic 3.5 inch with a capacity of 1.44 MB. It is not exactly classic, because it does not have two separate connectors for power and data, but rather a single flat cable that carries both data and power. The same goes for the hard disk: it has a single connector that carries both data and power. It is not an ESDI connector, but is a proprietary format used only in IBM PS/1s, like this one, and some IBM PS/2 model 30 models.
The operating system is loaded inside the computer's ROM, which is located under the hard disk and floppy disk. To access it you need to remove both the floppy disk, the hard disk and the metal piece that supports them. Below are the four ROMs. They are normal ROMs: I used four 27C020 memories to put the English software inside.
Actually you can use the 27C010. To use the 27C020 I had to split the program. I don't know if you are familiar with ROM, but by having an extra address line and not knowing what state it is in (whether at logical level 1 or 0), you could access two different parts of the memory. For this reason, I filled both parts of the ROM with the same program, so that the computer can always access the same instructions regardless of the state of that address line.
That's why the 27C020 has exactly double the memory of the 27C010, which I could have used. Only I didn't have it.
The computer was supplied with the IBM DOS version 4.01 system, and was loaded inside the ROMs, but you could also have diskettes. In fact, the computer provides a configuration utility that allows you to boot, therefore starting, either via floppy disk, via hard disk or via software found inside the ROM.
When I purchased this computer, so in 2023, almost two years ago, it had a black and white monitor, and this immediately seemed quite strange to me because, I ask, in 1991 who bought a computer with a black and white monitor? In fact, it was one of the reasons I hadn't used this computer right away. Having a '91 computer with a black and white monitor, when already in 1980 the Commodore VIC-20 was in colour, I was a little disappointed. It was also without a keyboard and without a mouse.
In fact, this keyboard here, the mechanical IBM Model M2 - you hear the classic clicks when you press the key, like the IBM Model M - I purchased later, but unfortunately it didn't work: it had some keys that didn't work. So I took it all apart; in practice it was a mess, because when it opens all those clips come off, all the supports for the various keys, and reassembling it was a mess.
The problem was that the board rests on the flexible printed circuit, commonly called a membrane, and tries to make contact thanks to the fact that the printed circuit board rests on the membrane. Unfortunately, evidently, the contact force was too weak because the plastic that holds the card pressed onto the membrane was quite damaged. So I cleaned everything, reassembled it, it worked quite well, but every now and then there is a column of keys that doesn't work, here on the numeric keypad. So, let's pretend nothing happened. I should reopen it, rearrange the card better, perhaps hold it down with some other support so that it presses well on the membrane.
There wasn't even a mouse, I bought a couple of different types. For example, this very nice one, original IBM, which in my opinion goes well with this computer and the years in which it was produced.
Subsequently I was given this color monitor, and there the situation had changed a little because I said: Damn! Now, with a color monitor, a '91 computer with a 286 processor... you can even have a little fun!
Before connecting the monitor to the computer, I had set up the entire tester to check that the voltage coming out of the monitor to power the computer was adequate: not too high and not too low, so as not to damage the computer. But in practice, during the test, the monitor had smoked! Luckily it was only the RIFA capacitor, the one used at the input of the supply voltage to filter it. Replacing it - and I did this recently - the monitor started up again without problems.
I also had to lubricate the fan a little because it was making noise. In short, after 33-34 years it is quite normal that these things need a little attention.
So, with the color monitor in place, the original keyboard and the original mouse, at this point I said: Why not also carry out the repair of the computer that was left there pending?
The computer needed some small adjustments... which weren't even that small, eh! Apart from the monitor, for which I had to change a capacitor, the computer did not keep the date and time. This isn't a big deal, except that in addition to the date and time it lost the configuration, so it didn't even remember it had the floppy disk.
How do I change the configuration of these computers? It's not like modern computers, where you press Delete, Esc, whatever, and go into BIOS setup. No! Here you must have a file, an executable, an .EXE that you load from the diskette, or keep it inside the hard disk, and it is used to modify the computer's configuration.
So I would have had to load a file from the diskette to tell him that the diskette exists... that is, the classic dog chasing its tail! They are those things that one says: And how do I do it?
Luckily I also have other IBMs, IBM PS/2 model 30, with the same hard disk connector, and so I moved this hard disk to another IBM. Then, using a floppy disk, I loaded the BIOS configuration program for this computer onto the hard disk. Remounting the hard disk on this computer, I did all the configurations and the diskette started again, but it still lost the configuration. So I had to replace the famous Dallas DS1287 with the nwX287, which is a modern alternative.
I had already made a video relating to this replacement, which however I had carried out on another computer, an IBM PS/2 model 30, not on this PS/1. But the concept is the same: you reach for the DS1287, remove it (in this case it was on a socket, so there wasn't even any need to solder anything) and in its place you put the nwX287 with a battery. Then you restart the computer and, using the configuration program, reconfigure the entire BIOS.
The computer was missing the serial port, which is this one. In fact, as you can see, these IBM PS/1s aren't exactly expandable. Basically it's all proprietary format, it doesn't even have an ISA connector. Basically, you would have to buy a riser card to put on here to get the ISA slots, but I didn't have one. I don't have the riser card. I didn't even have this serial card, so the computer was born only with the parallel and without the serial. This seemed a little inconvenient, because I use FastLynx to transfer data between new and old computers. FastLynx could use parallel, but I don't have the cable: I built the cable only for serial.
So, what did I do? By great luck I found this expansion and was able to buy it at a low price, an original IBM expansion.
While I was busy with all the repairs, I replaced the Dallas, then I mounted this board here, the original IBM serial expander. I returned the original hard disk, replacing these three small capacitors that were starting to leak acid. I noticed this because, looking at the PCB tracks, they were opaque near those capacitors. However, the original 30MB hard drive - a whopping 30MB! - had bad sectors and sometimes crashed when writing.
What did I do? Again with enormous luck, I found another hard disk of the same capacity and the same model, a WDL-330P. Also on this new hard disk I replaced the three capacitors and now it works really well: it reads and writes without any problem, so this problem is solved. I also kept the old capacitors aside; I'm keeping them for now, but I don't know if I'll keep them forever. These here were those of the old hard disk, which however has bad sectors. Instead, these here are those of the new hard disk, new so to speak, because it is still over 30 years old... but now it works very well, both with the new capacitors and with the old ones from before.
As I mentioned before, I replaced the original ROMs of the computer with the same ones, but in English, so I also have the computer in English. After all these operations, I had to transfer the files back to the hard disk. Because the hard disk I got didn't have anything from the IBM PS/1 inside. But not even the hard disk from before. In fact, someone had probably already messed around on this computer. Using FastLynx I took the files from the internet, found them in English and transferred them all. The computer now has all the software that was there when it was sold.
Well, now let's test turning on the computer! So I'll show it to you turned on, I'll show you the startup phase and then we'll play with it for a moment, let's try some utilities.
Do you want to hear the ignition sound? ASMR?
So, I wrote this using a little program in Turbo Basic. Do you remember the Turbo Basic? Not only could you program in Basic, but you could also compile and create an EXE file!
So, first of all, if we go into the configuration programs, which obviously I now have on the hard disk but weren't there before, when I had to do that operation I was telling you about putting the hard disk on another computer, we can see that this computer here can start in three ways: from the internal DOS which it has in the ROM, first the diskette and then in the ROM. Evidently before it was set to start only internally without looking at the diskette, or to start from the hard disk.
Not only that: we can use our own AUTOEXEC.BAT, which we made ourselves, because it is not found inside the ROM but we put it on the C: hard disk. So it occurred to me to start the Italian keyboard, because, since I had put the computer in English, the keyboard had an English layout according to him. Subsequently I said: Okay, come on, let's do this little program too, so it turns out that the computer is from the ValorosoIT channel!
So, let's see for a second. Again through the software we go to TB, Turbo Basic. This is the Basic: I had made this very simple program. Then you could compile and create a file. At this point, I placed this executable in C: and, using the AUTOEXEC.BAT file, loaded it at startup. So now let's see for a moment if we can distinguish which is the executable from the BAS. This could be the EXE. Let's see... Yes, it is this file that simply shows: ValorosoIT, www.valoroso.it, which is my website, my blog, where I put all the articles, videos, all the documentation accompanying this video. For example, the IBM PS/1 manual can be found on my website. I said: Let's do some publicity when the computer starts, before the system starts with the four windows, which allows you to navigate inside the computer.
Then, there is the possibility of seeing tutorials on how Works works and how the system works. There is also Microsoft Works, but I haven't used it yet. This came with the computer, but I haven't used it yet, so I can't show it to you at the moment.
Here you can load software onto your computer. Instead, IBM DOS is used to load the DOS operating system shell. So, MS-DOS can be used either with the command prompt, as has always been done, thus typing the various commands, or through the shell, which is this one here. This allows you to make small settings, as well as see where various files are on your computer, copy them, etc. We can return to the system with the four windows.
Here, inside the software, let's take a look at the performance of this computer with CheckIt. If you remember, I made a video in which I compared the performance of the CPUs of vintage computers compared to those of modern computers. To do this I used CheckIt, which allows you to measure Whetstones and Dhrystones, which are units of measurement that can also be used on modern computers.
So, let's measure the system's performance, then we'll compare it with that of the other computers that I had already measured some time ago and whose results I had already published. Here we have 1889 Dhrystones and 37,000 Whetstones. Among other things, as you point out, there is no mathematical coprocessor (FPU) on this computer and it cannot even be mounted, because on the other IBM PS/2 model 30, for example, I had mounted the mathematical coprocessor. If they had the Intel 8086 processor, I put the 8087 coprocessor in them; if they had the 286, I put the 287 on them. In this case, there is no socket on the motherboard at all, so the coprocessor cannot be mounted.
So, 1889 Dhrystone, which are practically fixed point operations, are exactly the same as those of the IBM PS/2 model 30. Precisely because it has the Intel 286 processor, therefore model 30 286, and they are the same whether the mathematical coprocessor is installed or the computer is used without it, because the mathematical coprocessor is useful for speeding up floating point operations. Other computers with less powerful processors obviously have a lower number of Dhrystones. For example, the Intel 8086 processor we are around 800.
And oh well, so that's it for this computer, which has a very respectable performance. Instead, as regards Whetstones, therefore floating point operations, the computer is somewhat penalized by the fact of not having the mathematical coprocessor (FPU). In fact, it loses to any other computer that has it.
For example, the IBM PS/2 model 30, however with an Intel 8086 processor and mathematical coprocessor, has a number of floating point operations which is a generous 239,000, compared to 37,000 on this computer here. So, in short, he's a little bit more unlucky on this one.
Just out of curiosity, a modern computer makes 147 G and obviously even more Giga Whetstone, so against the 37 K Whetstone of this computer. A modern one does 150 G, but certainly more. It depends on the computer model: I measured it on an Intel i5, but in reality there are much faster processors. So I can imagine that these 150 G can also become much more.
Well, another consideration you made in the comments is that not all software used the mathematical coprocessor. So, having the math coprocessor on the computer to make it faster was fine, however, other than using AutoCAD, which is drafting, and a few calculation programs, many of the programs didn't use it.
In fact, to do these floating point operations using the math coprocessor, I actually had to use CheckIt, because otherwise, if I had used Norton SysInfo, it wouldn't even have noticed the presence of the math coprocessor.
One last thing I want to talk about is IBM PS/1 emulation. If you don't want to buy the IBM PS/1 but still want to play with DOS, you have two options.
One is to use DOSBox, which on a modern computer allows you to start MS-DOS applications or even install your own version of MS-DOS, and then use the applications, programs and games. DOSBox is a generic emulator, it is not specific to the IBM PS/1.
Instead, a specific emulator for the IBM PS/1 is IBMulator, written as IBMulator. It's not exactly easy to use and configure, because you have to download it from the Internet.
After that, you also need to put the IBM PS/1 ROMs in a specific folder, because they don't come with the emulator, evidently for copyright reasons. So, if you have an IBM PS/1 you can dump the memory and use it, or alternatively you can do an Internet search and find them.
They are copied into the specific folder of the emulator, then obviously it would be necessary to build the hard disk or use the image of a pre-built hard disk containing all the programs that were supplied together with the IBM PS/1.
I hope you enjoyed this video on the IBM PS/1 and found some interesting ideas for your future experiments.
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And we'll see you in the next video! See you soon, bye bye!