Iirc, the turbo option started way back in the 8088/8086 era of motherboards although it wasn't on all systems. Come to think of it, I only remember seeing it on a few different types of 286 machines and I don't remember ever having to use it to run software.

My first 286 had a special BIOS setting and associated case light for going down to 8 MHz, but no actual turbo button. Normally it ran at 12 MHz, and games like Striker and Jump Joe/Janitor Joe were challenging to the point of being borderline unplayable. (Of course, being young and with limited options, that certainly didn't stop me from trying.)

Nothing wrong with MoSlo when it comes to a machine like that, really.

I don't remember ever using the "deturbo" mode on my old Tandy 1000 (286 8MHz). What I remember, compared to an 8088 XT, was that games ran better on the 286 and the XT simply ran them somewhat slow. These were mid-late '80s games.

It didn't have a turbo button but you could do a key combo to switch it into its slower 8088-ish mode.

Try Zaxxon....

I believe Flightmare runs too fast on anything more powerful than an IBM 5150. The first time I played it was on my Tandy 1000 SX which has a 286 Express Card installed, and I remember the game being absuredly difficult. Having recently taken another look at that game I'm convinced it was designed for even older systems and doesn't take newer systems into account properly.

Some really old games, notably the Kroz games, actually ask if you have a "Slow" or "Fast" system and adjust their delay rates or timing accordingly.

As for slowing things down, it was possible to toggle the 286 Express Card on and off on a whim with keyboard shortcuts, but this only works with the specific version of DOS included with the computer and BOTH of my disks, the original and backup, for running the 286 Express software died pretty much at the same time, as well as the copy I put on my bootup disk. (Lame.)

Depends on the motherboard, my 10MHz 286 board has an option in the BIOS setup for slow, normal and high speed.
http://i.imgur.com/O5Xjj.jpg

sorry for large image and crappy picture quality, but this setting seems to change the clock speed - according to norton sysinfo anyway. Slow is 6MHz, normal is 8MHz and high is 10. There is also a turbo button header, which seems to swap between 6 and 10MHz.

I've been thinking about ways to slow down a PC. I had an idea to slow down a 386. The idea is that you can cover all ground, from an early PC up to a 386. Also, the idea ATM is to do the slowdown "using hardware" only. I appreciate that utilities such as MoSlo are very good, but for now I just wanted a hardware only challenge.

The mobo in question is the one that DonutKing uses, in his 386 DX build thread here. These are the Contaq chipset-based mobos. Later on in this thread, I did some tests by replacing its osciallator. A benchmark results table of this experiment can be seen here, about half way down this page. The slowest osciallator I used in this testing was a 50MHz unit. But I've just looked online, and you can get oscillators that will fit this board as slow as 1MHz!

The only problem is that pulling these things off the board, and then pushing another one back in to the board is a nuisance. It takes about 10-30 seconds if the lid is off. I suppose you could always have several 386s, and put in various slow speed oscillators in to them. You could then benchmark these machines, and figure out roughly what speed era the machine is from.

Actually, I'm beginning to think this could solve my missing old IBM PC hardware (in terms of speed), and if for any reason my 286 project proves to be unsuccessful, it could also solve the 286 era gap too. The next thing I'll do is buy a small selection of very slow 14-pin oscis, and benchmark the Contaq 386 again. Another useful thing about this board is that you can set its bus speed to various speeds. Plus there's the turbo button too. OK, I'll shut up now about 386s in this 286 thread. 😊

Well, if you find any games that a 286 is too fast for, you can always buy sth like this : http://cgi.ebay.de/NEUES-BOARD-CPU-NEC-V20-80 … =item4840d53f57 . I've got one. You can fill the ram sockets with chips from vga cards, and you can have 1MB. You can also use regular 16 bit ISA cards(vga and multi i/o). You can't have an IDE HD, only floppies. This one when the turbo switch is on, it runs at 12MHz, but when it isn't it's really slow. 4.77MHz. I think it is fine to play anything really old....

Very nice mobo! It's really interesting that you are able to use regular 16-bit cards such as VGA and multi I/O inside this 8-bit mobo. Please can you explain why it is not possible to use an IDE based HDD? Thanks.

If you take an ISA multi I/O controller, all of it's functions (serials/parallel/joystick and floppy) are done by the 8bit part of the card. A few pins on the 16bit part are needed only for the hard disk controller. Also the BIOS of a board like that, doesn't have support for a HDD. There are ways to have an IDE HDD on a 8bit system. You need a suitable controller. Except finding an old MFM style HDD and a a matching controller, there are some other ways. You need a controller with it's own BIOS. If you are capable of soldering, I would recommend the XT-IDE diy controller, which allows you to connect a regular IDE disk.

Thanks for the info! Regarding the NEC V20 mobo, there seems to be several different sized empty sockets on it. I think I can count 5. Can you tell me how many different types of chips I need? I am guessing/hoping that I don't need to fill every different sized empty socket on the board. Also, can you attach an external battery to it? Thanks.

Ok, let me remember. One socket next to the cpu is for an 8087fpu. Next to the BIOS chip there is an empty socket of the same size. I don't know what you can't put on that. Perhaps some early pcs had some BASIC language on a chip, or even a dos version(I actually have an old 8086 laptop that has MS-DOS v3.1 on a chip, and it boots instantly). Next there are the memory sockets. You can find two type of sockets there. The regular (28 pin I think?) that can take chips like those on a VGA card, and some smaller ones that are called parity chips. I've discovered that parity isn't necessary, and works fine without them. And to answer your final question, you can't place a battery on that as it is, because it simply doesn't have a real time clock! That was common for old pc-xts. So there were after market cards for general purposes that had built in clocks, with battery sockets on them. I've bought one, and it works like that : you run a small utility that saves the date and time on the chip that is on the card, and then each time you boot, you run a seperate utility at autoexec.bat, that simply updates the dos date and time commands.... And finally, what I forgot to tell you, if you ever plan to get one of those, make sure you have an old keyboard that has an AT-XT switch. Those keyboards while switched to AT may be used to anything from 286 and newer, but for anything older you need to switch it to XT. Otherwise any regular keyboard won't work, even if the plug is the same....

Wow, thanks for the info, especially the warning about the keyboard. I would never have known that. I only use AT to PS/2 adapter cables, with new keyboards. It's very unlikely that this adapter+new keyboard combo would work.

You're welcome. I was lucky enough, when the guy that sold me my 286 gave me an old keyboard which is switchable. Later I bought 2 old pcs plus a lot of other stuff including 6-7 keyboards from another guy for just 30euros. So there was a couple of other switchable keyboards, but the best part was a really old 85key keyboard, which is XT-type only(won't work on anything newer....) So I washed that one, and it's ready for my oldest PC!

[Would you still bother with this if it turned out there weren't any games that were too fast for a 286-based PC..?]

Jorpho wrote:

[Would you still bother with this if it turned out there weren't any games that were too fast for a 286-based PC..?]

I am inclined to say that I wouldn't bother. Part of me wants an old PC, just to complete my collection of junk. But there seems to be too many obstacles here: the necessity to obtain a "custom built" IDE controller, and a special keyboard too. Plus those RAM chips. And that really nice looking NEC board is a bit pricey. Nah, I think I'll pass on this. I'm going to concentrate on my 386 board, and grab a handful of oscillators, to see if I can effectively reduce its speed down to 8088/80286 levels using hardware only...

Update: I think both of those NEC mobos that Markk linked to above have just been sold. BTW, I didn't buy them.

I think that seller may have a lot of them. I bought mine last year and was the last one then, but then he had some more. Right now he has another on a different add.