weird old ROM chips...

Interesting! "Fascinating"

Well, the 17VDC indicates the devices are MOS - I'd look into old Rockwell parts from the mid-70s.

Any date codes on any ICs on the motherboard? If you can identify the year then you can use the IC Master catalog from that year to find who made ROM that were 1K X 8. I checked the 1978 guide and couldn't find any likely suspects, but perhaps you will have more luck searching a bit more through.

John :-#)#

OK, I see the Wang 2000E/F was produced in January 1976, so check out the IC Master for 1975 (assuming you can find one) or earlier for the ROM.

What do you mean by pin 13 "nAR"? No Connection visible? Did you do a resistance check to common in case they used an early multi-layer PCB and the ground plane is invisible by being in the middle plane?

John :-#)#

Looks like 1978-1979 time period.

(yes, the pins are *rusty*)

That doesn't sound like something that would have ended up online...

The schematics labelled that pin AR with a bar over it. I suspect it's "address ready".

As for the year discrepancy, note the "in case they need to be replaced AGAIN" in my original post ;-)

If the power supply loses a rail, the ROMs are the first chips to die from it :-P

If you take pin 1 as ground and pin 9 as Vcc it's the same as the Signetics 2600 masked ROM, but that's an NMOS part (circa 1978) that runs on +5 volts. A couple GI ROMs from 1977 also use pin 1 and 9 as gnd/vcc. And other GI parts use +5/-[some voltage] as "ttl compatible" PMOS.

So this is a PMOS part from several years earlier. The Signetics sheet cross references EA4600 and EA4900. Electronic Arrays, as I remember.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

Ah, thanks, the picture helps. Certainly the date codes are from 77 through 79. The manufacturers logo "E/A" looks familiar. I'll have to check that tomorrow in my IC Masters if I have time...figuring out the manufacturer should enable us to find the part number.

These are masked ROMs of course.

John :-#)#

Of course. I was hoping I could read them out and save the data at least. If they get toasted I'll have to figure out how to create replacements from today's technology.

John Robertson schrieb:

Looks like "Electronic Arrays Inc.":

Tilmann

Maybe this page can add some information

Cant find your part#'s there but still...

Also found this

Pages like these makes me num.. :)

Yeah, I've been though the museums some. I figured this place was an easy first choice for finding the base part *if* it was a common part back then, I'll try to hunt down someone who's fiddled with these parts before, next.

Thanks for the info. /me wishes stuff back then was on the Internet already :-P

If you can access the data and address bus directly you could always read the entire bank of ROM using something like a Fluke 9010 or 9100 (if the CPU is common) or even wire up an adapter so you could connect to an Eprom reader. Schematics would help for this project!

John:-#)#

That's a help - it certainly matches the age and logo. Now DJ can post a note here - something like: Subject: Electronic Arrays ROM data book needed...

John :-#)#

Thought of that already. I have plenty of embedded MCU boards with enough I/O to watch the whole address/data bus, if I dared power it up. I'd rather read them *before* risking them. The other trick would be getting the computer to cycle through all the addresses.

Dead easy (peek/loop etc) in basic - just literally a few lines.

Just a few more lines to open/copy/close a disk file.

You're assuming this computer's basic has instructions for reading the

The disk format is also not compatible with anything else.

Heck, if this were easy, I wouldn't need help, would I ;-)

"Ian Field" schreef in bericht news:OZw8q.4866$ snipped-for-privacy@newsfe27.ams...

Don't think so. The number of ROMs make me think they do not contain a monitor program but the microcode of the processor. I've seen more old machines functioning this way. Most pre PC minicomputers did so. I like to see the schematics if possible. They *may* give enough information to find out how the chips have to be operated. For instance do you need to provide

petrus bitbyter