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3BABY
Joined: 19 Oct 2011
Posts: 28
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 Posted: Wed Aug 15, 2012 11:07 pm Post subject: Identify this chip - Intel DIP 24 |
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HI Guys,
so i have recently purchased some Intel Chips off ebay, they were sold as P8253 , P8254 Programmable Interval Timers (PITs) and the nice picture on the left hand side had a picture of a DIP24 with P8254-2 on the top.. i thought cool, i need these for my project so Buynow x 6, they arrive and they all have printed on the top (please see pics below):
8519909 9028
PI M A A40431
L0292178
&c INTEL 78
and on the bottom:
40230190
BB G1 28
no signs of 8253 or 8254 for the interval timers.. what have i got in my hand now? some batch of 8253's or 8254's that were never printed with the marketed part number OR some lucky barrel IC ?
any help would be much appreciated
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Robev
Joined: 10 Mar 2006
Posts: 1607
Location: New Zealand
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| Posted: Wed Aug 15, 2012 11:32 pm Post subject: |
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I hope they were cheap 
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Neon_WA
Joined: 08 Nov 2008
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Location: Perth, West Australia
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3BABY
Joined: 19 Oct 2011
Posts: 28
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| Posted: Thu Aug 16, 2012 12:08 am Post subject: |
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thanks for the reply...
Robev - i may be keen on some of yours..  |
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Neon_WA
Joined: 08 Nov 2008
Posts: 6468
Location: Perth, West Australia
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| Posted: Thu Aug 16, 2012 12:14 am Post subject: |
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by the copyright date.. unlikely 8253s but could be P8254-2
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3BABY
Joined: 19 Oct 2011
Posts: 28
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| Posted: Thu Aug 16, 2012 12:22 am Post subject: |
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| Neon_WA wrote: | | by the copyright date.. unlikely 8253s but could be P8254-2 |
ok thnaks, i cant find much on the web about 8254/8253 numbers or pics the only thing i was thinking of a IBM PC Mainboard and having a look on there. another problem is i cant even really test it much as i dont have anything to compare to.. maby ill just have to get hold of a genuine article and get it working on a system and then swap out with one of these units to see if behavior is the same? |
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3BABY
Joined: 19 Oct 2011
Posts: 28
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| Posted: Mon Aug 27, 2012 6:19 pm Post subject: |
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| Robev wrote: | | I hope they were cheap |
| Neon_WA wrote: | | by the copyright date.. unlikely 8253s but could be P8254-2 |
Well i can confirm that the above is either 8253 or 8254 or 82C54 i haven't checked it at a high clock (i.e. > 8MHz) but i intend to (which will rule out 8253).. but i can confirm that the unit works the same as one of the 8254's i purchased from Robev at a clock input of 32KHz
thanks again Robev for sending those units so quick!! |
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3BABY
Joined: 19 Oct 2011
Posts: 28
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| Posted: Mon Aug 27, 2012 6:33 pm Post subject: |
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Confirmed to run @ 4Mhz and 10Mhz clock input so im thinking we either have 8254-2 or 82C54, my guess is 8254-2 equivalent
actually Robev your Intel Stamped 8254 runs at 10Mhz too.. but i guess 100% of the time im not sure so safe bet is to run them at the rated 8Mhz Max, so in saying that they could just be exactly 8254 |
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Robev
Joined: 10 Mar 2006
Posts: 1607
Location: New Zealand
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| Posted: Mon Aug 27, 2012 6:42 pm Post subject: |
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| 3BABY wrote: | Confirmed to run @ 4Mhz and 10Mhz clock input so im thinking we either have 8254-2 or 82C54, my guess is 8254-2 equivalent
actually Robev your Intel Stamped 8254 runs at 10Mhz too.. but i guess 100% of the time im not sure so safe bet is to run them at the rated 8Mhz Max, so in saying that they could just be exactly 8254 |
I guess like most IC's they will run overclocked for a period of time but like you say "better to run them at the rated clock speed to be safe"
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Elar
Joined: 16 Jul 2003
Posts: 641
Location: Tallinn, Estonia
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| Posted: Tue Aug 28, 2012 4:21 am Post subject: |
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| It is fairly easy to determine if it's 8254 or 82C54. Apply static clock leveles to all three channels and power up. 82C54 remains stone cold. NMOS 8254 will be warm to the touch in about minute or so. |
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