hi guys! I need to have an obsolete 2708 eprom programmer-reader.. It's very difficult to find modern eprom programmers that do this! I have buyed a willeim but it does everithing but 2708!! Well if it's possible i would make one. I'm very good skinned as electronic handy man , but i can't know how to make it. Can someone help me? And if someone got an old eprom programmer let me know!
-- Joe Leikhim K4SAT "The RFI-EMI-GUY"©
-- Joe Leikhim K4SAT "The RFI-EMI-GUY"©
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Yes i'm doing this in the last 2 months! :)
Exaclty! I'm monitorizing ebay.com ebay.de ebay.fr and ebay.it
But no luck, just modern type eprom , from 2716 and up!
I think Needham's used to make a reasonably priced programmer. You can probably find one on eBay if you watch for a while.
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The fifth post here may shed some light on why:
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--------------------------------------------------------------------- The Andromeda Research EPROM+ programmer can handle the 2708. Price is reasonable at US $289 plus shipping.
-- Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
Willem might work if you make up an adapter to supply the -5V and translate the pins.
You also may be able to adapt a more modern eprom to the task, I've done this with RAM chips, disconnecting the -5V and adding a jumper to make newer 4164 RAM chips work in place of the original chips on Williams game boards. I've adapted Dallas battery backed SRAMs to replace various obsolete writable memory chips too.
ke
Can't you just cobble up an adapter to treat your 2708 as if it were a larger memory device. So what if the high read addresses come us as "00" or "FF" Hex. Just edit it with a text editor. Or am I missing something here?
-mpm
The pinout is very nearly the same; I don't think it'd be all the difficult to sub in a 2716.
Isaac
Unless you really want to keep it 'vintage'...
Arie de Muynck
. snipped-for-privacy@twister2.libero.it...
tBetter. Put the data in 2 blocks both 0-1K and 1K to 2K so it doesn't matter if the MSB is hi or low.
GG
The 2708 requires two additional supply voltages, +12 and -5 in addition to the +5 required by 2716 onwards. That's probably why most programmers don't support it.
Should not be hard to make one though - I made a 2716 programmer in high school, and you could probably do a 2708 if you got the extra voltages. I used an 8255 I/O chip wired into an expansion memory socket on my Z80 computer; but you could also hang the 8255 off a parallel port as an I/O expander. Either that, or get a USB-connected microcontroller with enough I/O pins. For programming you'll need a VPP supply and something that can generate a pulse of the right width
- back then I didn't want to trust software timing, today you might. Or you could use a 2716 in an adapter as the replacement and only have to worry about accomplishing the readout.
On a sunny day (Thu, 5 Jun 2008 08:22:12 -0700 (PDT)) it happened cs snipped-for-privacy@hotmail.com wrote in :
Hey, I used 2 Z80 PIOs ;-)
I have S-100 microcomputers capable of reading and writing 2708s. A couple of them actually boot into monitors stored on 2708s. Not willing to sell, but if you are in the Washington, DC area, I would be happy to dump and/or program some for you. email me if interested.
Bill Sudbrink
The 2708 is similar to larger, newer EPROMs except for the extra supply voltages, for reading.
However, IIRC, it uses a different programming algorithm where you are supposed to cycle through the entire memory a number of times.
This thing is pretty old, thirty-plus years.
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com
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Fantastic work! I have contacted them! I think that i will buy this!
Yes , that's the point, i don't wanna to modify all my equipement!
On a sunny day (Thu, 05 Jun 2008 19:00:46 GMT) it happened "JA" wrote in :
Would it not be a lot cheaper to make a little plug in board with for example a
2716? These once existed with SRAM and battery too IIRC. Depends on how many EPROMS of that pre-historic age you need to replace.
The differences between the 2708 EPROM and the next device in the series:
2708 2716 +----\\/----+ ---+ 1 |A7 24| VCC | VCC 2 |A6 23| A8 | A8 3 |A5 22| A9 | A9 4 |A4 21| VBB | VPP (-5V on 2708) 5 |A3 20| WE/CS | /OE 6 |A2 19| VDD | A10 (-12V on 2708) 7 |A1 18| VPP | /CE 8 |A0 17| D7 | D7 9 |D0 16| D6 | D6 10 |D1 15| D5 | D5 11 |D2 14| D4 | D4 12 |GND 13| D3 | D3 +----------+ ---+ASCII pinouts from:
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