old EPROM

I have an old eprom burner/reader that supports that chip. What sort of something newer did you want to put it in, or did you just want .hex files?

Bill

Wow, my first home built computer used those...that was a long long time ago :)

Watch out, the 2708 requires three supplies even to read it. +12, +5, and -5.

I could read it as a 2716 with an adapter socket and the additional supplies.

Regards, tm

If you have an FTDI USB to TTL serial cable, you could use a few binary counters and a parallel-in-serial-out shift register on the 2708's output. The FTDI serial chip supports a bitbang read/write mode in its C library; bang away at the parallel-in-serial out shift register, use one of the counters as a divider and divide that clock down by 1/8th and apply it to the binary counters driving the 2708's address lines. Read the data in the C program and write it to a file.

Or stick the 2708, HC4040 ripple counter, and a PIC into a solderless breadboard and send the data off to a PC over an RS-232 serial link.

Best regards, Spehro Pefhany

An adapter to interface an existing programmer seems more sensible to me.

Probably so. It would be a nuisance to set up.

John

Sure, that's another way. I don't have a 24-pin header lying around to solder wires to so it would take until Monday afternoon to get that up and running. The breadboard could be done tonight and still have time to get a cappuccino.

Best regards, Spehro Pefhany

The RubeGoldberg approach?

I have an old Link programmer (ISA) that should still work. I even have

Cheers

Yeah, I'll have to make an adapter and hook up the silly extra power supplies. And tell the programmer that it's reading a 2764 or something. I think the 2708 was an nmos part, and the -5 was a substrate supply. I think.

See below.

Careful to use a "stupid" programmer as any sort of adapter used in a "smart" programmer could toast the device!

The 'adapter', assuming the old programmer has a ZIF socket, is just a 24-pin wirewrap socket. Put the 2708 in the WW socket, trim the oddball power pins short, and wire-wrap from those short pins to the extra supplies. The long WW socket pins go into the ZIF socket, of course.

A 2708 has 10 address lines, so you can connect it directly to a small controller. You'll also need 8 input pins for data. So getting those supllies is biggest problem and keeping them clear from rest of electronics. I wondet if you can find any data for the chip.

"LM" schreef in bericht news: snipped-for-privacy@g2g2000vbs.googlegroups.com...

Sure. There are at least a Texas and a National datasheet out there. Google may find more.

petrus bitbyter

All this stuff, doing it this way & that way, seem a lot harder than dropping it in an envelope & getting your data back...no cost, unless you want the old part back. Or maybe you really just wanted to moan about not being able to read out your data...in which case, forgettaboughtit!

bill

"John Larkin" schreef in bericht news: snipped-for-privacy@4ax.com...

Yes, I can. An old DOS-machine has the required voltages inside, a bidirectional printerport for reading the data, a 10-bits counter (some 4040 for instance) and a quick and dirty GWBASIC program.

As an alternative I have an old homebrew serial EPROM programmer that can be easily adapted to read a 2708. The required voltages are available already. Though I'd have to search the dark corners of the attick to find it.

petrus bitbyter

You can do the same with a stack of normal IC sockets. I've done that before to use flash devices in sockets intended for an EPROM. IIRC 2 wires needed do be swapped.

It is a perfect job for a picaxe (28X2) - putting the power supplies onto a proto board (7812,7805,7905 - how hard is that!) would take as long as writing the software