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View Full Version : Intel P24D-S.....? O.o



Raven
April 2nd, 2009, 05:00 PM
What the hell is this? I've never layed eyes on such a CPU before. From what I was able to google up, and this was little, it is a 486-era CPU by Intel, but it is 66mhz, which is mid-era Pentium speed. Was this box a super-expensive server-room box of the 486-era? It was used as an "Automated Voice Administrator", basically a phone box for an office. It has a mono monitor with an odd serial-looking connection (tho male is on the monitor and female on the board. I haven't opened her up yet, but it has DOS 6.22 and some proprietary software (which i yoinked out of the autoexec to boot to a shell) and 4MB of ram... It has a Quantum Fireball for an HDD and a 1.44 MB flop. That's all I know so far. Thoughts? What's up with this CPU and why is there no info on the net?:confused:

Vlad
April 2nd, 2009, 05:22 PM
it is 66mhz, which is mid-era Pentium speed. The 468 went to 100 MHz, the Pentium started at 60. Its barely the starting point of the Pentium.


What's up with this CPU and why is there no info on the net?Typing that into the Wikipedia got me:


There are two major versions of the DX2. Identified by P24 and P24D, the latter has a faster L1 cache mode called "write-back" that improves performance. The original P24 version only offers the slower "write-through" cache mode.Its a 486 with write-back it seems.

IBMMuseum
April 2nd, 2009, 06:50 PM
Its a 486 with write-back it seems.

More correctly, an Intel 486DX2 (in 50 and 66MHz versions) or 486DX4 (I´ve only seen the 100MHz versions, not a 75MHz) that can set the L1 cache to write-back mode...

The following ¨S-specs¨ (http://www.ibmmuseum.com/david/intel486.htm):

SX954: 486DX2-50
SX955: 486DX2-66
SX158: 486DX4-100
SX209: 486DX4-100
SK896: 486DX4-100
SK096: 486DX4-100

The 486DX2 versions will return CPUID 0436h when the L1 is in write-through mode, 0470h when in write-back mode. The 486DX4-100 versions (which all seem to be 3 volt models, with 16Kb of L1 cache) will return CPUID 0483h when the L1 cache in write-through mode, 0490h when in write-back mode. These CPUIDs are unique to the write-back models, and can be used to detect them in software without opening the case. I am aware of a few (late model) 486 systems that can enable the L1 in write-back mode (BIOS support), or an easy utility could be written to do the same thing (if CPUID is 0436h or 0483h, then set L1 to write-back mode).

Raven
April 3rd, 2009, 05:22 PM
The 468 went to 100 MHz, the Pentium started at 60. Its barely the starting point of the Pentium.



I could have sworn there was a 33Mhz Pentium (66, 100, 133, and 266 as well) and that 486's started at ~20Mhz (though I had no idea they went up to 100!).

Anywho thanks for clarifying that, I'm used to seeing a 486 boot with "Intel 486DX" or what-have-you. Good to know what I've just acquired.

DreadStorm
April 3rd, 2009, 05:39 PM
If it helps, I remember clearly that the P24T was a Geniune Pentium, but in an ODP (OverDrive Processor) package that slipped nicely into a Socket-3 Mobo. 60MHz or 66MHz I can't recall, but it was one of those...

So if you see one of those, they're just as handy - and rare.

IBMMuseum
April 3rd, 2009, 07:33 PM
I could have sworn ...that 486's started at ~20Mhz...

Actually there was 16MHz 486SXs at the beginning...

IBMMuseum
April 3rd, 2009, 07:38 PM
If it helps, I remember clearly that the P24T was a Genuine Pentium, but in an ODP (OverDrive Processor) package that slipped nicely into a Socket-3 Mobo. 60MHz or 66MHz I can't recall, but it was one of those...

So if you see one of those, they're just as handy - and rare.

63 (with a 25MHz external clock) or 83MHz (with 33MHz base clock). The multiplier was 2.5 for the internal clock rate. I cover them within the same page, and at the bottom of the chart.

DreadStorm
April 3rd, 2009, 08:35 PM
Then again...heh

I was remembering what I read in ads - as far as how they were set up mostly. I didn't notice them. But I DID find the 486DX4 CPU I plan to put to use shortly.