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Question on EPROM programmers

Hi there:

I would like to program a 2708 EPROM to run in my Vector Graphic MZ (not 
currently functional so I can't use the Vector PROM card) - I look on 
eBay and see some relatively inexpensive EPROM programmers, but they 
don't list the 2708 as supported, but do list the 2716. These chip 
pintouts seem to be nearly identical, will these programmers program the 
2708 or do I have to find a "vintage" programmer?

Regards,
   Gord
0
gtulloch1 (1)
11/7/2004 4:37:16 PM
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You have to find a vintage programmer.

Basically (this is an over-simplification, but it's accurate enough), 
the 2716 was the first "modern" EPROM chip.  1702's and 2708's (and even 
earlier chips) were "early" EPROMS and can't be programmed by most 
modern progrmmers.  FWIW, the 2708 is much easier to program than the 1702.

The easiest and best way to program a 2708 is probably with a Cromemco 
"Bytesaver" board in an S-100 system.


Gord Tulloch wrote:

> Hi there:
> 
> I would like to program a 2708 EPROM to run in my Vector Graphic MZ (not 
> currently functional so I can't use the Vector PROM card) - I look on 
> eBay and see some relatively inexpensive EPROM programmers, but they 
> don't list the 2708 as supported, but do list the 2716. These chip 
> pintouts seem to be nearly identical, will these programmers program the 
> 2708 or do I have to find a "vintage" programmer?
> 
> Regards,
>   Gord
0
WatzmanNOSPAM (5711)
11/7/2004 4:33:53 PM
"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:418E5078.1050008@neo.rr.com...
> You have to find a vintage programmer.
>
> Basically (this is an over-simplification, but it's accurate enough),
> the 2716 was the first "modern" EPROM chip.  1702's and 2708's (and even
> earlier chips) were "early" EPROMS and can't be programmed by most
> modern progrmmers.  FWIW, the 2708 is much easier to program than the
1702.
>
> The easiest and best way to program a 2708 is probably with a Cromemco
> "Bytesaver" board in an S-100 system.
>
>
> Gord Tulloch wrote:
>
> > Hi there:
> >
> > I would like to program a 2708 EPROM to run in my Vector Graphic MZ (not
> > currently functional so I can't use the Vector PROM card) - I look on
> > eBay and see some relatively inexpensive EPROM programmers, but they
> > don't list the 2708 as supported, but do list the 2716. These chip
> > pintouts seem to be nearly identical, will these programmers program the
> > 2708 or do I have to find a "vintage" programmer?
> >
> > Regards,
> >   Gord

You can easily adapt a new chip by simply bendind out a few pins and
jumpering them to ground.

The 2708 uses the same data, adress, and control pinout of the 2716.  There
are only two lines that are different:

19 - Vdd (2708) : A10 (2716)
21 - Vbb (2708) : Vpp (2716)

If you use a 2716 all you need to do is bend out pins 19 & 21 and jumper
them to pin 12.


Randy


0
randy38 (638)
11/7/2004 6:17:52 PM
Randy,

It took me a while to figure out what you are saying, but I think that 
you are suggesting:

-Use and program a 2716
-Put the 2716 into the 2708 socket, grounding pins 19 & 21 to pin 12.

Right?


Randy McLaughlin wrote:

> "Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
> news:418E5078.1050008@neo.rr.com...
> 
>>You have to find a vintage programmer.
>>
>>Basically (this is an over-simplification, but it's accurate enough),
>>the 2716 was the first "modern" EPROM chip.  1702's and 2708's (and even
>>earlier chips) were "early" EPROMS and can't be programmed by most
>>modern progrmmers.  FWIW, the 2708 is much easier to program than the
> 
> 1702.
> 
>>The easiest and best way to program a 2708 is probably with a Cromemco
>>"Bytesaver" board in an S-100 system.
>>
>>
>>Gord Tulloch wrote:
>>
>>
>>>Hi there:
>>>
>>>I would like to program a 2708 EPROM to run in my Vector Graphic MZ (not
>>>currently functional so I can't use the Vector PROM card) - I look on
>>>eBay and see some relatively inexpensive EPROM programmers, but they
>>>don't list the 2708 as supported, but do list the 2716. These chip
>>>pintouts seem to be nearly identical, will these programmers program the
>>>2708 or do I have to find a "vintage" programmer?
>>>
>>>Regards,
>>>  Gord
> 
> 
> You can easily adapt a new chip by simply bendind out a few pins and
> jumpering them to ground.
> 
> The 2708 uses the same data, adress, and control pinout of the 2716.  There
> are only two lines that are different:
> 
> 19 - Vdd (2708) : A10 (2716)
> 21 - Vbb (2708) : Vpp (2716)
> 
> If you use a 2716 all you need to do is bend out pins 19 & 21 and jumper
> them to pin 12.
> 
> 
> Randy
> 
> 
0
WatzmanNOSPAM (5711)
11/7/2004 7:43:50 PM
"Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
news:418E7B95.6090804@neo.rr.com...
> Randy,
>
> It took me a while to figure out what you are saying, but I think that
> you are suggesting:
>
> -Use and program a 2716
> -Put the 2716 into the 2708 socket, grounding pins 19 & 21 to pin 12.
>
> Right?
<snip>

Yes, I tend to add another socket bending out the desired pins on the new
socket.  I dislike cutting an original board and find adding a socket as an
adapter is easy and reversible.

The same thing goes for flash/EEPROM/etc.  Sometimes you need to add a tall
24 pin socket with a 28 or 32 pin socket plugged into it to get it above
other components.

The pinout of .600" memory devices are fairly consistent from the 2708 on.


Randy
www.s100-manuals.com


0
randy38 (638)
11/7/2004 8:20:10 PM
"Randy McLaughlin" <randy@nospam.com> wrote in message
news:Irvjd.41337$T_.28590@bignews4.bellsouth.net...
> "Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
> news:418E7B95.6090804@neo.rr.com...
> > Randy,
> >
> > It took me a while to figure out what you are saying, but I think that
> > you are suggesting:
> >
> > -Use and program a 2716
> > -Put the 2716 into the 2708 socket, grounding pins 19 & 21 to pin 12.
> >
> > Right?
> <snip>
>
> Yes, I tend to add another socket bending out the desired pins on the new
> socket.  I dislike cutting an original board and find adding a socket as
an
> adapter is easy and reversible.
>
> The same thing goes for flash/EEPROM/etc.  Sometimes you need to add a
tall
> 24 pin socket with a 28 or 32 pin socket plugged into it to get it above
> other components.
>
> The pinout of .600" memory devices are fairly consistent from the 2708 on.
>
>
> Randy
> www.s100-manuals.com

I forgot to mention:  With larger memory devices it is possible to have
multiple ROM images with an external switch to select between them.  Long
address lines (to the switch) will not have ringing problems since they will
contain stable info.


Randy
www.s100-manuals.com


0
randy38 (638)
11/7/2004 8:27:06 PM
Gord Tulloch wrote:
> 
> I would like to program a 2708 EPROM to run in my Vector Graphic
> MZ (not currently functional so I can't use the Vector PROM card)
> - I look on eBay and see some relatively inexpensive EPROM
> programmers, but they don't list the 2708 as supported, but do
> list the 2716. These chip pintouts seem to be nearly identical,
> will these programmers program the 2708 or do I have to find a
> "vintage" programmer?

They won't IIRC. The 2708 was the second generation of Eproms, the
2716 the third, and the 1702 the first.

-- 
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

0
cbfalconer (19194)
11/7/2004 8:44:43 PM
Thanks guys, excellent advice!

Randy McLaughlin wrote:
> "Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
> news:418E7B95.6090804@neo.rr.com...
> 
>>Randy,
>>
>>It took me a while to figure out what you are saying, but I think that
>>you are suggesting:
>>
>>-Use and program a 2716
>>-Put the 2716 into the 2708 socket, grounding pins 19 & 21 to pin 12.
>>
>>Right?
> 
> <snip>
> 
> Yes, I tend to add another socket bending out the desired pins on the new
> socket.  I dislike cutting an original board and find adding a socket as an
> adapter is easy and reversible.
> 
> The same thing goes for flash/EEPROM/etc.  Sometimes you need to add a tall
> 24 pin socket with a 28 or 32 pin socket plugged into it to get it above
> other components.
> 
> The pinout of .600" memory devices are fairly consistent from the 2708 on.
> 
> 
> Randy
> www.s100-manuals.com
> 
> 
0
gtulloch (2)
11/9/2004 11:31:22 PM
"Gord Tulloch" <gtulloch@shaw.deleteme.ca> wrote in message
news:erckd.167139$Pl.52197@pd7tw1no...
> Thanks guys, excellent advice!
>
> Randy McLaughlin wrote:
> > "Barry Watzman" <WatzmanNOSPAM@neo.rr.com> wrote in message
> > news:418E7B95.6090804@neo.rr.com...
> >
> >>Randy,
> >>
> >>It took me a while to figure out what you are saying, but I think that
> >>you are suggesting:
> >>
> >>-Use and program a 2716
> >>-Put the 2716 into the 2708 socket, grounding pins 19 & 21 to pin 12.
> >>
> >>Right?
> >
> > <snip>
> >
> > Yes, I tend to add another socket bending out the desired pins on the
new
> > socket.  I dislike cutting an original board and find adding a socket as
an
> > adapter is easy and reversible.
> >
> > The same thing goes for flash/EEPROM/etc.  Sometimes you need to add a
tall
> > 24 pin socket with a 28 or 32 pin socket plugged into it to get it above
> > other components.
> >
> > The pinout of .600" memory devices are fairly consistent from the 2708
on.
> >
> >
> > Randy
> > www.s100-manuals.com


2708's are:

Expensive.
Hard to find.
Hard to find programmer for.
Easy to replace with newer device without modifying original board (beyond a
couple of jumpers).


Randy


0
randy38 (638)
11/9/2004 11:46:57 PM
Gord Tulloch wrote:

> I would like to program a 2708 EPROM to run in my Vector Graphic MZ (not 
> currently functional so I can't use the Vector PROM card) - I look on 
> eBay and see some relatively inexpensive EPROM programmers, but they 
> don't list the 2708 as supported, but do list the 2716. These chip 
> pintouts seem to be nearly identical, will these programmers program the 
> 2708 or do I have to find a "vintage" programmer?

The 2716 and, I believe, all later EPROMs use TTL voltage on
the data lines when programming.  The 2708 requires high voltage
pulses on the data lines, requiring a much more complicated
programmer.

There once was a 2758, which was a 2716 where only half worked
and wired up differently.  Or maybe wired up the same.

Use the socket with pins bent out and resoldered, that is what
we did when 2716's were new.  2708's weren't liked even then.

-- glen

0
gah (12851)
11/10/2004 5:49:58 AM
"glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
news:a_hkd.320695$wV.238857@attbi_s54...
> Gord Tulloch wrote:
>
> > I would like to program a 2708 EPROM to run in my Vector Graphic MZ (not
> > currently functional so I can't use the Vector PROM card) - I look on
> > eBay and see some relatively inexpensive EPROM programmers, but they
> > don't list the 2708 as supported, but do list the 2716. These chip
> > pintouts seem to be nearly identical, will these programmers program the
> > 2708 or do I have to find a "vintage" programmer?
>
> The 2716 and, I believe, all later EPROMs use TTL voltage on
> the data lines when programming.  The 2708 requires high voltage
> pulses on the data lines, requiring a much more complicated
> programmer.
>
> There once was a 2758, which was a 2716 where only half worked
> and wired up differently.  Or maybe wired up the same.
>
> Use the socket with pins bent out and resoldered, that is what
> we did when 2716's were new.  2708's weren't liked even then.
>
> -- glen


No the 2708 is simple to program and only one pin needs a higher voltages
and then only during programming (pin 18 as I remember).

You are probably thinking of earlier EPROMS like 1702, 5204, etc.


Randy


0
randy38 (638)
11/10/2004 6:12:14 AM
"Randy McLaughlin" <randy@nospam.com> wrote in message
news:ehikd.5129$WC6.2064@bignews3.bellsouth.net...
> "glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
> news:a_hkd.320695$wV.238857@attbi_s54...
> > Gord Tulloch wrote:
> >
> > > I would like to program a 2708 EPROM to run in my Vector Graphic MZ
(not
> > > currently functional so I can't use the Vector PROM card) - I look on
> > > eBay and see some relatively inexpensive EPROM programmers, but they
> > > don't list the 2708 as supported, but do list the 2716. These chip
> > > pintouts seem to be nearly identical, will these programmers program
the
> > > 2708 or do I have to find a "vintage" programmer?
> >
> > The 2716 and, I believe, all later EPROMs use TTL voltage on
> > the data lines when programming.  The 2708 requires high voltage
> > pulses on the data lines, requiring a much more complicated
> > programmer.
> >
> > There once was a 2758, which was a 2716 where only half worked
> > and wired up differently.  Or maybe wired up the same.
> >
> > Use the socket with pins bent out and resoldered, that is what
> > we did when 2716's were new.  2708's weren't liked even then.
> >
> > -- glen
>
>
> No the 2708 is simple to program and only one pin needs a higher voltages
> and then only during programming (pin 18 as I remember).
>
> You are probably thinking of earlier EPROMS like 1702, 5204, etc.
>
>
> Randy

I forgot to mention that it was common to use 3 9v batteries to generate Vpp
easily.

The problem is not making a 2708 programmer, it would be easy to modify a
willem programmer or create a whole new one.  The only "fancy" thing about
the Cromemco ByteSaver is the DC to DC converter which can be replaced with
a standalone PS (or 3 9v batts).

It's just easier to use something besides a 2708.


Randy


0
randy38 (638)
11/10/2004 6:33:59 AM
<snip everything>

Anyone interested in the details of the 2708 I have technical details on my
website:

http://www.s100-manuals.net/Harte-manuals/Intel%208080%20Manual/Intel8080Manual-2.pdf

Starting at page 63 (5-45), please note Intel 8708 is the 2708.

The 2708 needs 3 voltages to read and 4 to program, flash ROMs are available
that only requires 5v for everything.


Randy


0
randy38 (638)
11/10/2004 6:46:54 PM
Randy McLaughlin wrote:

(snip)

> No the 2708 is simple to program and only one pin needs a higher voltages
> and then only during programming (pin 18 as I remember).

> You are probably thinking of earlier EPROMS like 1702, 5204, etc.

Maybe I was remembering the 1702, but the 2708 is still not easy
to program.  For the 2716 you apply Vpp, and then pulse one of
the other pins with a TTL level pulse for the appropriate time.

For the 2708 you pulse Vpp to between 25 and 27 volts for between
0.9 and 1.1ms, with less than 2us rise and fall times, and up
to 20ma.  If you overshoot 27V you can destroy the chip.
The circuitry to generate a pulse like that is not so easy to
make, and is not normally built into EPROM programmers since
2708 days.  Fast rising pulses can easily overshoot 27V.

-- glen

0
gah (12851)
11/11/2004 5:01:49 AM
"glen herrmannsfeldt" <gah@ugcs.caltech.edu> wrote in message
news:YmCkd.393574$D%.270872@attbi_s51...
> Randy McLaughlin wrote:
>
> (snip)
>
> > No the 2708 is simple to program and only one pin needs a higher
voltages
> > and then only during programming (pin 18 as I remember).
>
> > You are probably thinking of earlier EPROMS like 1702, 5204, etc.
>
> Maybe I was remembering the 1702, but the 2708 is still not easy
> to program.  For the 2716 you apply Vpp, and then pulse one of
> the other pins with a TTL level pulse for the appropriate time.
>
> For the 2708 you pulse Vpp to between 25 and 27 volts for between
> 0.9 and 1.1ms, with less than 2us rise and fall times, and up
> to 20ma.  If you overshoot 27V you can destroy the chip.
> The circuitry to generate a pulse like that is not so easy to
> make, and is not normally built into EPROM programmers since
> 2708 days.  Fast rising pulses can easily overshoot 27V.
>
> -- glen


I'll have to check the docs again but I am positive you are wrong, the Vpp
is not very sensitive to exact voltage and it may be left at Vpp without
pulsing.  One of the earlier programmers I used (Wire-Wrapped) used 3 9v
batteries and you just plugged and unplugged one battery to enable/disable
Vpp (with a diode for biasing).

With Vpp applied writing is possible otherwise it can only be read, i.e.
extremely simple in technology only the fact that you need four power
supplies is complicated.

Even the programming pulse width is not critical short pulses work as long
as you follow with a read to verify data and repeat as needed.  No critical
timing or voltages.


Randy


0
randy38 (638)
11/11/2004 9:56:45 AM
Reply: