VOGONS


First post, by BLockOUT

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Hey there, im trying to understand the 486 socket3 "socket upgrade kits" that were normally sold for OLD motherboards that only worked with 5volt cpus

i have seen some of those in the market, but i just don´t understand why some models of those upgrade sockets got jumpers for setting it as "X3" and setting it as "X4"

I have on my hands some of those socket upgrade kits and these do not have jumpers on them.. so for example if i test the ones i have with lets say an AMD5X86 on a really old motherboard (486 that has a 486 dx2 50mhz cpu on the motherboard and the motherboard does not accept any higher cpu speed, ) then in theory I should get 25mhz multiplied by 4 wich is 100mhz. Is that right?

what i don´t get is why some of those upgrade kits have a setting to set it at X3, i mean why would you want to set it as x3, since the best is 4x.

Or perhaps my upgrade sockets that don´t have any jumper on them can only do x3 ? and there are special upgrade kits that can do x4 ? Im kind of confused why some had jumpers and some did not.

Reply 1 of 15, by Caluser2000

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The majority of DX4/100s etc were really x3(clock tripled) and not x4 cpus as they seem to indicate. Just a marketing ploy really.

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 2 of 15, by Doornkaat

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The last 486 chips (i.e. Am5x86) supported the 4x multiplier or the 3x multiplier, previous 486DX4 chips had the 3x multiplier. Both needed 3.x volt to run.

Edit: Also I'm not sure if the late chips supported both multiplier settings but if your system is stable at 50MHz FSB but your CPU won't go past 150MHz it's better to run 50*3 than 33*4. Depending on system and software 50*3 can also beat 40*4. Having both options is a good thing.

Reply 3 of 15, by dionb

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Am5x86 already had the multiplier pin, the upgrade modules just implemented a jumper to select it.

That was relevant as quite a few older 486 boards (prime candidates for an upgrade like this) had fixed bus speeds, up to and including 50MHz, so a fixed 4x multiplier would have been very problematic over 33MHz (200MHz examples do exist, but they're rare and that's wildly out of spec). I have such a board (Micronics EISA board intended for 486DX-50) and intend to run one of these CPUs on at 3x50MHz it once I get it fully working.

Reply 4 of 15, by BLockOUT

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I still don´t get it tho.
for example this board is from a ps/1 and it has a a dx2-50mhz and it says the only way to upgrade it is with an Overdrive 83 as an upgrade.

http://www.win3x.org/uh19/public/motherboard/ … anual/34351.pdf

the only cpu options that they give you are: Processor 80486SX/80487SX/ODP486/80486DX/80486DX2 - Processor Speed 25/33/50(internal)/66(internal)MHz

jumpers for Type :
80486SX
80487SX
ODP486
80486DX
80486DX2

that means the motherboard can only give me 25mhz that is doubled by the CPU multiplier, so i get 50mhz

1) if i put a 5x86 with a CPU upgrade socket (that don´t have jumpers) then in theory i should get 100mhz on the ps/1.
2) And if i put a 5x86 with a CPU upgrade socket (that has x3 and x4 jumper) then in theory i should get 100mhz or 75mhz ?

im i right?

Reply 5 of 15, by Caluser2000

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BLockOUT wrote on 2021-07-26, 18:16:
I still don´t get it tho. for example this board is from a ps/1 and it has a a dx2-50mhz and it says the only way to upgrade it […]
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I still don´t get it tho.
for example this board is from a ps/1 and it has a a dx2-50mhz and it says the only way to upgrade it is with an Overdrive 83 as an upgrade.

http://www.win3x.org/uh19/public/motherboard/ … anual/34351.pdf

the only cpu options that they give you are: Processor 80486SX/80487SX/ODP486/80486DX/80486DX2 - Processor Speed 25/33/50(internal)/66(internal)MHz

jumpers for Type :
80486SX
80487SX
ODP486
80486DX
80486DX2

that means the motherboard can only give me 25mhz that is doubled by the CPU multiplier, so i get 50mhz

1) if i put a 5x86 with a CPU upgrade socket (that don´t have jumpers) then in theory i should get 100mhz on the ps/1.
2) And if i put a 5x86 with a CPU upgrade socket (that has x3 and x4 jumper) then in theory i should get 100mhz or 75mhz ?

im i right?

My Acer Across 486DX2/50 is running fine and stable at 33Mhz. IE its now a 486DX2/66...😀

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 7 of 15, by Caluser2000

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BLockOUT wrote on 2021-07-26, 20:06:

still i don´t get it, what would be the difference with my ps/1
if i use a socket adapter that has x4 and x3 jumpers and if i use a socket adapter that has no jumpers at all

Just pick one, fire up you system and see if the cpu smoke up;)

Jumpers on the interposer usually mean you can enable/disable something in the CPU interposer. You need to look a the specific documentation for that specific interposer/cpu combination.

The Kingston chip in the pic below has no jumpers and just plugs in.

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There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 8 of 15, by dionb

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BLockOUT wrote on 2021-07-26, 20:06:

still i don´t get it, what would be the difference with my ps/1
if i use a socket adapter that has x4 and x3 jumpers and if i use a socket adapter that has no jumpers at all

You need to distinguish between what the CPU does and what the motherboard does.

The motherboard determines the bus clock speed. If the CPU can handle it, it runs using that speed. If not, not.
The CPU determines the multiplier (if applicable), so a DX/2 runs at twice the bus speed, a DX/4 at three times and the Am5x86 at three or four times the bus speed.

Note that the ODP also has multiplier selection, it just works differently: with fan active it runs at 2.5x the bus speed; remove the fan (or if it dies), and it runs at 1x bus speed.

If your PS/1 or Aptiva board has a bus speed selection, you can choose 25MHz or 33MHz bus speed. If not, it's determined by the clock crystal, which would need replacing for a different speed. Last week I could have told you, as I had the same board, but I sold it to someone who had the Aptiva it fitted into.

So, if your board is stuck on 25MHz and you're not willing/able to change that crystal, your options are:
- PODP63 (or 83) at 2.5x 25 = 63MHz
- PODP63 (or 83) at 1x 25 = 25MHz
- Am5x86 at 4x 25 = 100MHz
- Am5x86 at 3x 25 = 75MHz

Given that the PODP is rated at at least 63MHz and the Am5x86 at 133MHz, there's no reason not to run either option at the highest available choice. In most applications, an Am5x86 at 100MHz will clearly beat a PODP at 63MHz. The exceptions would be software using the FPU (numeric co-processor), which is much more powerful on the PODP. But very few games that would run on this hardware do so.

If you have some other interposer with a different CPU and/or no jumper to set multiplier, you are just stuck with whatever is on it.

Reply 9 of 15, by Caluser2000

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On the other hand my Hypertech 586 upgrsade has thee jumper as seen below:

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Last edited by Caluser2000 on 2021-07-27, 02:51. Edited 1 time in total.

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 10 of 15, by BLockOUT

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dionb wrote on 2021-07-26, 20:33:
You need to distinguish between what the CPU does and what the motherboard does. […]
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BLockOUT wrote on 2021-07-26, 20:06:

still i don´t get it, what would be the difference with my ps/1
if i use a socket adapter that has x4 and x3 jumpers and if i use a socket adapter that has no jumpers at all

You need to distinguish between what the CPU does and what the motherboard does.

The motherboard determines the bus clock speed. If the CPU can handle it, it runs using that speed. If not, not.
The CPU determines the multiplier (if applicable), so a DX/2 runs at twice the bus speed, a DX/4 at three times and the Am5x86 at three or four times the bus speed.

Note that the ODP also has multiplier selection, it just works differently: with fan active it runs at 2.5x the bus speed; remove the fan (or if it dies), and it runs at 1x bus speed.

If your PS/1 or Aptiva board has a bus speed selection, you can choose 25MHz or 33MHz bus speed. If not, it's determined by the clock crystal, which would need replacing for a different speed. Last week I could have told you, as I had the same board, but I sold it to someone who had the Aptiva it fitted into.

So, if your board is stuck on 25MHz and you're not willing/able to change that crystal, your options are:
- PODP63 (or 83) at 2.5x 25 = 63MHz
- PODP63 (or 83) at 1x 25 = 25MHz
- Am5x86 at 4x 25 = 100MHz
- Am5x86 at 3x 25 = 75MHz

Given that the PODP is rated at at least 63MHz and the Am5x86 at 133MHz, there's no reason not to run either option at the highest available choice. In most applications, an Am5x86 at 100MHz will clearly beat a PODP at 63MHz. The exceptions would be software using the FPU (numeric co-processor), which is much more powerful on the PODP. But very few games that would run on this hardware do so.

If you have some other interposer with a different CPU and/or no jumper to set multiplier, you are just stuck with whatever is on it.

awesome, thanks for the explanation , very clear now. Yea my board hat no jumpers visible for 33mhz so im stuck at 25mhz.
One thing i would like to know is this:

"If you have some other interposer with a different CPU and/or no jumper to set multiplier, you are just stuck with whatever is on it.":

an Am5x86 with a socket 3volt adapter that has no jumpers in that adapter, that it would be 25mhz x 4 = 100mhz
im i right?

Reply 11 of 15, by Caluser2000

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BLockOUT wrote on 2021-07-26, 20:56:
awesome, thanks for the explanation , very clear now. Yea my board hat no jumpers visible for 33mhz so im stuck at 25mhz. One t […]
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dionb wrote on 2021-07-26, 20:33:
You need to distinguish between what the CPU does and what the motherboard does. […]
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BLockOUT wrote on 2021-07-26, 20:06:

still i don´t get it, what would be the difference with my ps/1
if i use a socket adapter that has x4 and x3 jumpers and if i use a socket adapter that has no jumpers at all

You need to distinguish between what the CPU does and what the motherboard does.

The motherboard determines the bus clock speed. If the CPU can handle it, it runs using that speed. If not, not.
The CPU determines the multiplier (if applicable), so a DX/2 runs at twice the bus speed, a DX/4 at three times and the Am5x86 at three or four times the bus speed.

Note that the ODP also has multiplier selection, it just works differently: with fan active it runs at 2.5x the bus speed; remove the fan (or if it dies), and it runs at 1x bus speed.

If your PS/1 or Aptiva board has a bus speed selection, you can choose 25MHz or 33MHz bus speed. If not, it's determined by the clock crystal, which would need replacing for a different speed. Last week I could have told you, as I had the same board, but I sold it to someone who had the Aptiva it fitted into.

So, if your board is stuck on 25MHz and you're not willing/able to change that crystal, your options are:
- PODP63 (or 83) at 2.5x 25 = 63MHz
- PODP63 (or 83) at 1x 25 = 25MHz
- Am5x86 at 4x 25 = 100MHz
- Am5x86 at 3x 25 = 75MHz

Given that the PODP is rated at at least 63MHz and the Am5x86 at 133MHz, there's no reason not to run either option at the highest available choice. In most applications, an Am5x86 at 100MHz will clearly beat a PODP at 63MHz. The exceptions would be software using the FPU (numeric co-processor), which is much more powerful on the PODP. But very few games that would run on this hardware do so.

If you have some other interposer with a different CPU and/or no jumper to set multiplier, you are just stuck with whatever is on it.

awesome, thanks for the explanation , very clear now. Yea my board hat no jumpers visible for 33mhz so im stuck at 25mhz.
One thing i would like to know is this:

an Am5x86 with a socket 3volt adapter that has no pins in that adapter, it would be 4x or 3x ? do you know?

Go get the documentation. What brand/speed of upgrade Kingston, Hypertech etc..

There's a glitch in the matrix.
A founding member of the 286 appreciation society.
Apparently 32-bit is dead and nobody likes P4s.
Of course, as always, I'm open to correction...😉

Reply 12 of 15, by dionb

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BLockOUT wrote on 2021-07-26, 20:56:
[...] […]
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[...]

awesome, thanks for the explanation , very clear now. Yea my board hat no jumpers visible for 33mhz so im stuck at 25mhz.
One thing i would like to know is this:

"If you have some other interposer with a different CPU and/or no jumper to set multiplier, you are just stuck with whatever is on it.":

an Am5x86 with a socket 3volt adapter that has no jumpers in that adapter, that it would be 25mhz x 4 = 100mhz
im i right?

Probably, as that's the default setting for the Am5x86, but it depends on the adapter. It could have that pin set high or floating, in which case it will give 3x. To give 4x, it needs to be tied low to ground. You can mod that yourself (enough GND pins on the socket) if required.

For a lot more info on the Am5x86: http://web.inter.nl.net/hcc/J.Steunebrink/amd5x86.htm

Reply 13 of 15, by BLockOUT

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today i did a lot of testing with some of those adapters

the system is an ibm ps/1 that came with 486 50mhz.

i started to test with

1) kingston turbochip
2) no brand 5v to 3v adater + amd 5x86
3) a DELL 5v to 3v adapter + amd 5x86
4) 486 overdrive 100

1)
turbochip kind of worked it gave me 100mhz
used it for a while but the fan is about to die. it froze once on DOS, not sure if it was because of Incompatibility. it was detected as 100mhz in norton commander.

2 and 3)
Lots of problems, booted loaded to win 3.1 and some seconds after it reboots the pc, then gave messages on screen "about out of range." sometimes i was abe to run norton commander to find out that it was detected as 75mhz until it gave black screen

4) no problems, rock solid , detects it as 75mhz.
at least its not 50mhz like the original system.

not sure why my adapters made a mess, no jumpers on them, cpu detected as 75mhz. at least the kingston turbochip was good and got detected as 100mhz.

Should i buy another adapter? a more compatible one? are those still sold online?

Reply 15 of 15, by rmay635703

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BLockOUT wrote on 2021-08-25, 17:57:

i guess these adapters were not so compatible after all

It was not past IBM to go out of its way to prevent non-IBM sanctioned upgrades
If a bios update exists it may help

Also worth noting some “upgrade” devices could be damaged in some way before you installed, others pull all the power from the CPU socket which can be a problem on marginal motherboards (too much power)

A few hardwire write through or write back which can create chaos on older systems (needs to match the systems capabilities)

Lastly some historical “auto configured” motherboards sometimes actually do support 3.3v and decide to feed that into your 5v overdrive causing instability

From what I’ve found the 25mhz IBM systems have an identical motherboard to the 33mhz units, even the clock generator is the same, only difference is a few different traces to the clock Gen, careful modification to hardwire the clock generator could provide 33mhz