2708 Programming Algorithm?

From: Joe <rigdonj_at_cfl.rr.com>
Date: Mon May 6 16:51:24 2002

Dick,

  No I didn't. It's "Intel 8080 Microcomputer Systems User's Manual", September 1975. I've got it right here in front of me. FWIW I don't think the 27xxs were even out when this data book was printed. There's no 27xx parts in here at all. The "Intel MCS-80 User's Manual", October 1977 lists the 2716 and stresses that it's a 5v only part but it doesn't list the 2708 at all. Both books state the the 8708 uses standard power supplies; +12v, +/- 5v.

  The older manual also list a 8704 that's a 512 x 8 bit part (instead of 1k x 8), perhaps that's what you're thinking of.

   Joe


At 12:51 PM 5/6/02 -0600, you wrote:
>I do believe you've misread part of the spec's, Joe. The 8708, IIRC, is a
>5-volt-only version of the 2708, otherwise masqueraded as the 2758. I got one
>of these back in the mid-late '70's, on an 8748 evaluation board, and as such,
>it was my first 5-volt-only EPROM. They were described by the Intel FAE as
>2716's with a flaw in one half or the other, and they were available in two
>types, with either a high or low enable where the 2716 had an address line.
>
>Dick
>
>----- Original Message -----
>From: "Joe" <rigdonj_at_cfl.rr.com>
>To: <classiccmp_at_classiccmp.org>
>Sent: Monday, May 06, 2002 3:29 PM
>Subject: Re: 2708 Programming Algorithm?
>
>
>> Steve,
>>
>> I don't have the programming instructions for the 2708 but I do have them
>for the intel 8708 and intels later manuals state that they're the same.
>Here's what I have in the sept 1975 8080 Microcomputer Systems User's manual.
>>
>> At 08:21 AM 5/6/02 -0700, you wrote:
>> >I obtained a bunch of 2708 UVEPROM's, and I'd like to
>> >be able to program them. As you may know, they require
>> >a different algorithm than the 2716 and on, and three
>> >voltages, +5, +12, and -5.
>> >
>> >I'm building a little board that will program 1/2 (the
>> >upper or lower) of a 2716 to a 2708 (I can program
>> >2716's). But I can't find a description of the
>> >algorithm that is detailed enough. What I think I know
>> >is:
>> >
>> >1. The /OE line must be high
>>
>> Intel says to raise the CS*/WE line to +12 volt.
>>
>>
>> >2. select address and data (start at addr 0)
>>
>> Correct. A note here says that the logicx levels for the address, data
>and voltage supply lines are the same as for the read mode.
>>
>> >3. bring PGM line from 0 to 27 volts for 1 mSec,
>>
>> Correct except you can use 25 (min) to 27 (max) volts according to the
>manual.
>>
>> then
>> >drop back to 0 (this seems very strange)
>>
>> You have to allow for the setup time for the new address and data. The
>times are 10uS (min) for each but they could be different for the 2708.
>>
>> >4. repeat 100 times per address (not all at once,
>>
>> NO. This isn't what's in the intel manual. It says one programming pulse
>per address per loop. And that a loop is one pass through all the addresses.
>You have to repeat the loop until N (passes) x Tpw (programming pulse width)
>>= 100mS.
>>
>>
>>
>>
>> >increment the address lines and loop to avoid
>> >"overheating" a byte.
>> >5. drop /OE and verify.
>>
>>
>> "Note that programming and read loops can be alternated"
>>
>>
>> >
>> >
>> >Does anybody have an authoritative description, and a
>> >current requirement for the +5, +12, -5, and
>> >programming pulse? Thanks.
>>
>> It varies according to the temperature but the max occurs at low temp and
>is about 11ma for Icc _at_5.25v, 65ma for Idd @12.6v with CS*/WE high and about
>35 ma with CS*/WE low, 41ma for Ibb _at_-5.25v with CS*/WE high and about 17ma
>with CS*/WE low.
>>
>> The programming pulse current is typically 10mA with 20mA max.
>>
>> Have fun!
>>
>> Joe
>>
>>
>> >
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>>
>>
>
>
Received on Mon May 06 2002 - 16:51:24 BST

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