You mean adapter? https://www.microconnectors.com/ps-2-to-at-ke … -to-din-5-male/

PS/2 is also called "mini-DIN". Am I right assuming this is basically the same connector simply with a smaller form factor?

mtest001 wrote on 2024-11-01, 10:10:

PS/2 is also called "mini-DIN". Am I right assuming this is basically the same connector simply with a smaller form factor?

The interface electrically is the same, that's what makes passive adapters possible.
But the connector is not just smaller, it's different, at the very least ps/2 keyboard connector has 6 pins, not 5.
There are 5-pin mini DIN, but they're not arranged the same way as big old DIN's.

mtest001 wrote on 2024-11-01, 10:10:

PS/2 is also called "mini-DIN". Am I right assuming this is basically the same connector simply with a smaller form factor?

Depends on how you define "same connector". Mini-DIN is indeed a series of smaller form factor connectors that is in spirit similar to the DIN connectors, like being available in different pin counts and having a round shield connector. On the other hand, there are also some key differences between DIN and mini-DIN. The typical 5-pin DIN connector as used for example on the PC/XT/AT keyboard was originally used for stereo audio input/output on tape recoreders. They were intentionally designed in a way that the older 3-pin DIN connector used for mono audio input/output would fit as well, just connecting to the left-channel pins of the 5-pin stereo pinout. On the other hand, all standardized different pin-count mini-DIN connectors are keyed in a way that you can't fit a lower pin count plug into a higher pin count socket, using a plastic keying pin that is positioned diffently and prevents also damage to the pins if they don't match the hole positions of the unfit socket. For example, the plastic pin in the 4-pin S-Video mini-DIN plug prevents insertion into the 6-pin PS/2 keyboard/mouse connector socket, and the same way the plastic pin in the 6-pin plug prevents trying to force it into a 4-pin socket bending the extra 2 pins. This is quite helpful for mini-DIN, as their pins are thinner and thus less sturdy than classic DIN pins.

For keyboard sockets: The PS/2 6-pin mini-DIN carries (nearly) the same signals as the 5-pin DIN in the IBM AT and AT compatible systems. The same type of 5-pin DIN connection was also used on the IBM PC and XT, but the protocol was incompatible. Nothing will be damaged when confusing XT and AT keyboards, because the supply voltage pins are identical, and IIRC both the XT and the AT protocol uses open-collector drivers on the data lines - yet AT keyboards don't work on XTs and vice versa. There are dual-protocol keyboards that can auto-detect whether they are connected to an XT or AT and auto-switch protocols, but that doesn't change the fact that the protocols themselves are incompatible. So the PS/2 keyboard jack is, considering fuction and signals, identical to the AT keyboard jack, just smaller. Out of the 6 or 5 pins, only four are used. In the very ancient days of PC history, the 5th pin of the DIN plug was used to send a "reset" signal to the keyboard. The "reset" function might have been present on very early AT-style machines, but many later XT keyboards and most if not all AT keybaords ignored it. This signal was meant to not need a reset generator inside the keyboard to initialize the scanning processor, but use the reset signal that already was present in the computer. The reset signal was never on the PS/2 socket, that's why I wrote "nearly the same signals" at the start of this paragraph. You won't find computers with a PS/2 socket that accept XT keyboards, but rumor has it that some dual-protocol XT/AT keyboards were shipped with PS/2 plugs as well as DIN plugs, so you might find a PS/2 style keyboard that supports the XT protocol, although this is useless unless you use a separate mini-DIN-to-DIN adapter to connect the keybaord to connect the keyboard to an XT.

Who, thanks for the comprehensive answer. Btw I am looking for a PS2 bracket to "upgrade" my socket7 system that has a PS2 header on the mobo. These are a bit hard to find these days...

mtest001 wrote on 2024-11-02, 14:10:

Who, thanks for the comprehensive answer. Btw I am looking for a PS2 bracket to "upgrade" my socket7 system that has a PS2 header on the mobo. These are a bit hard to find these days...

https://www.ebay.com/itm/391942848851

PARKE wrote on 2024-11-02, 15:03:

mtest001 wrote on 2024-11-02, 14:10:

Btw I am looking for a PS2 bracket to "upgrade" my socket7 system that has a PS2 header on the mobo. These are a bit hard to find these days...

https://www.ebay.com/itm/391942848851

Just note that the pinout for PS/2 header on the motherboard is not standardized. You may need to shuffle the pins in the 2x5 (or whatever) connector around, according to your motherboard actual pinout.

since this topics come up, i need some help narrowing down my search for an old IBM PS/2 i had bit over 20 years ago, i got it from an old school friend around 2001, theres very few things i can remember about it, the main thing being that it had large din sockets for keyboard and mouse, i never had the original mouse so had to get an adapter for a PS2 one, the back of the case looked like this

it had the same amount of ports (ive seen others with less) the one i had was identical except it had dins instead of PS2 ports
the case i think looked like one of these

it came with the classic grey surround monitor and obviously the classic IBM keyboard with a din connector, as for specs i dont remember but i think it was a 486DX2 possibly, it ran win95, and i used to use it for playing heretic,doom, fallout1 and red alert, not very demanding i know, it wouldnt do quake 2, but after some fiddling i got it to run the pc version of sonic 3d, which requires a 70mhz cpu, also mine had a cdrom drive. most of the pics i've been looking at, aside from the one above dont have a cd drive and all have PS/2 ports, i thought mine might have been a PS/1 but it looks like they also have PS/2 ports. is there anyone here who would have any idea which models/line of IBM's, have a similar case and fit theses specs, 60-70mhz cpu, din ports for KB&mouse, and capable of connecting a cdrom drive? also the back of the case was the same layout as the pic above.

DudeFace wrote on 2024-11-02, 21:01:

is there anyone here who would have any idea which models/line of IBM's, have a similar case and fit theses specs, 60-70mhz cpu, din ports for KB&mouse, and capable of connecting a cdrom drive? also the back of the case was the same layout as the pic above.

IBM introduced the PS/2 ports with the earliest PS/2 models, the Model 50 (with 286 processor) and the Model 25/30 (originally 8086). As far as I know, IBM never went back to DIN sockets, so either your system was just an IBM lookalike, or it was modded. I've neither heard of a system having a 5-pin DIN socket for a mouse, nor a mouse with a 5-pin DIN connector, so this is either a very exotic system, or you misremember something.

mkarcher wrote on 2024-11-02, 21:53:

DudeFace wrote on 2024-11-02, 21:01:

is there anyone here who would have any idea which models/line of IBM's, have a similar case and fit theses specs, 60-70mhz cpu, din ports for KB&mouse, and capable of connecting a cdrom drive? also the back of the case was the same layout as the pic above.

IBM introduced the PS/2 ports with the earliest PS/2 models, the Model 50 (with 286 processor) and the Model 25/30 (originally 8086). As far as I know, IBM never went back to DIN sockets, so either your system was just an IBM lookalike, or it was modded. I've neither heard of a system having a 5-pin DIN socket for a mouse, nor a mouse with a 5-pin DIN connector, so this is either a very exotic system, or you misremember something.

thanks for the reply, thats interesting, it was definitely an IBM no doubt but not sure what cpu it was running, i just assumed it was a 486DX2(may have confused that with another system could have actually been an older 286/386) as it ran sonic3d which requires a 70mhz cpu, not sure if its possible to run on a 286 or if a 286 can run win95 at a decent speed, it was definitely din for mouse as i had to go to my local computer shop to pick up an adapter for ps2 to din (which i still have), im sure i remember the din sockets being on the left (looking at it from the back, opposite to the pic above) the I/O panel was identical otherwise,

i just looked up a pic of a model 55, that has ps2 ports which are also on the left, but on mine it had a riser for the expansion cards which sat horizontally, the system must have been upgraded as it had enough power to run sonic3d, so cpu,ram,video must have been upgraded also had a cdrom drive, and also it had a sound card with a game port (i bought one of those gravis psx pads to play sonic3d) as for the motherboard and cpu maybe it wasnt original, i've searched many sites looking at lots of pics but still cant figure it out, i wonder if there are any other motherboards with 2 din ports and the same I/O layout that could fit in the same case? since the other parts had been upgraded its possible the mainboard was as well.

mkarcher wrote on 2024-11-01, 14:33:

all standardized different pin-count mini-DIN connectors are keyed in a way that you can't fit a lower pin count plug into a higher pin count socket

That's generally a good thing, but depending on the situation it can also be a hindrance (when you want to support different devices in the same connector).
4pin mini-DIN are used for SVideo, so NVidia and ATI had some nonstandard variation of 7 or 9pin mini-DIN connectors that was 4-pin compatible. That way it could accept standard SVideo cables but also use the extra pins for other features. Several years ago I was looking for a source for those for a project I was fiddling with, but if they were ever available to the public it seems they're impossible to find now. I couldn't even figure out if they have a name. It seems the only way to get them is to manually desolder them from old video cards.

You won't find computers with a PS/2 socket that accept XT keyboards, but rumor has it that some dual-protocol XT/AT keyboards were shipped with PS/2 plugs as well as DIN plugs, so you might find a PS/2 style keyboard that supports the XT protocol, although this is useless unless you use a separate mini-DIN-to-DIN adapter to connect the keybaord to connect the keyboard to an XT.

The 386SX Wang we had when I was a kid used PS2 connectors, but the keyboard had the XT/AT switch. Later I got another copy of that keyboard and the switch was missing. I suppose it was originally a DIN keyboard that got gradually updated and ours was an in-between version that the switch had not yet been deleted from.

shamino wrote on 2024-11-03, 10:36:

mkarcher wrote on 2024-11-01, 14:33:

all standardized different pin-count mini-DIN connectors are keyed in a way that you can't fit a lower pin count plug into a higher pin count socket

That's generally a good thing, but depending on the situation it can also be a hindrance (when you want to support different devices in the same connector).
4pin mini-DIN are used for SVideo, so NVidia and ATI had some nonstandard variation of 7 or 9pin mini-DIN connectors that was 4-pin compatible. That way it could accept standard SVideo cables but also use the extra pins for other features. Several years ago I was looking for a source for those for a project I was fiddling with, but if they were ever available to the public it seems they're impossible to find now. I couldn't even figure out if they have a name. It seems the only way to get them is to manually desolder them from old video cards.

i've got an nvidia 7950gt i think it has the 7 pin din as an s-video lead fits in it, they usually come with 1 of 2 types adapter 1 for a combination of s-video/yellow rca and composite the other type just has s-video and composite, ive heard that one of the sockets is compatible with either megadrive 2 or sega saturn av cables, tho i havent confirmed it as i have a megadrive 1 and i sold my saturn some years ago, might be worth looking in to if you need to source replacements.

None of them are compatible with Sega AV cables since these cables use 9 and 10 pin connectors while the video card things are all 7 pin with completely different ararngement and functions. There are some set-top-box AV cables that fit and function with the video cards but there's no standard there either.

Tiido wrote on 2024-11-04, 09:29:

None of them are compatible with Sega AV cables since these cables use 9 and 10 pin connectors while the video card things are all 7 pin with completely different ararngement and functions. There are some set-top-box AV cables that fit and function with the video cards but there's no standard there either.

you're right its not the same i just had a quick look, it was the 9 pin connector i was refering to rather than the 7 pin svideo compatible, even still the sega connectors are similar but missing one of the pins at the the bottom so yeah not much good.

I believe Sega used a standard mini-DIN, so because of how mini-DIN is intentionally not downward compatible, it meant there was no way Sega could make it fit a 4pin SVideo cable. If Sega had wanted to support it, they'd have had to route SVideo through their breakout adapter since the standard mini-DIN layouts wouldn't allow the pins to be in the right places.

It's an unusual case where NVidia/ATI's use of a proprietary, nonstandard connector was more user-friendly than using the industry standard part.

DudeFace wrote on 2024-11-02, 21:01:

it had large din sockets for keyboard and mouse, i never had the original mouse so had to get an adapter for a PS2 one

Wasn't this called "mouseport" or "serial-mouseport"? If you look on eBay you can find example of mice with a larger DIN connector, not PS2, for example this one : https://www.ebay.com/itm/176455916366

mtest001 wrote on 2024-11-04, 16:31:

Wasn't this called "mouseport" or "serial-mouseport"? If you look on eBay you can find example of mice with a larger DIN connector, not PS2, for example this one : https://www.ebay.com/itm/176455916366

I guess this is one of the "bus mouse" variants. They were often called "bus mouse", because the mouse controller (in the PC) was directly connected to the ISA bus, whereas the external mouse device has no logic - it just sends the raw encoder data from the X/Y quadrature encoders (4 signals) and the 3 buttons (3 signals) to the ISA card. Add Ground and a supply voltage, and you will get 9 signals that were typically fit into a mini-DIN 9-pin jack (e.g. "Microsoft InPort Mouse") or a DE-9 connector (e.g. "Microsoft Bus Mouse"). This is also how the Amiga mouse worked. Some later models were dual protocol and supported serial as well as a bus-mouse protocol. See https://www.minuszerodegrees.net/msmouse/Micr … oft%20mouse.htm for a list of different kinds of Microsoft mice. Some kind of bus mouse interface (possibly compatible to the MS InPort Mouse) was present on some ATI mach ISA graphics cards.

As all of these mice were interfaced to ISA card, the connector can not be bigger than mini-DIN or SUB-D, as it wouldn't fit the slot bracket.

mtest001 wrote on 2024-11-04, 16:31:

DudeFace wrote on 2024-11-02, 21:01:

it had large din sockets for keyboard and mouse, i never had the original mouse so had to get an adapter for a PS2 one

Wasn't this called "mouseport" or "serial-mouseport"? If you look on eBay you can find example of mice with a larger DIN connector, not PS2, for example this one : https://www.ebay.com/itm/176455916366

not too sure on this tbh, the only other pc's i had with large dins were older AT's and those were just for the keyboard, when i got the IBM my friend didnt have the mouse so i went to my local computer shop looking for a large din mouse and all the guy had to offer was a ps2 to din adapter, think it was actually for keyboard but it worked with a standard ps2 mouse, this was in 2001 so ps2 was already the standard by then, hopefully someone will have an idea of what kind of IBM/motherboard used these two din ports, as all my searches have not got me anywhere so far.

PARKE wrote on 2024-11-02, 15:03:

https://www.ebay.com/itm/391942848851

Thank you, I just bought one. It always hurts me to have to order such kind of parts from the other end of the Atlantic but alas... This is the world we live in.