weird old ROM chips...

John Robertson schrieb:

Ah, thanks, the picture helps. Certainly the date codes are from 77
through 79. The manufacturers logo "E/A" looks familiar.

Looks like "Electronic Arrays Inc.":
http://www.elnec.com/support/ic-logos/manufacturer-description/?manuf=Electronic+Arrays
http://www.antiquetech.com/companies/EA.htm

Tilmann

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 Robertson <spam_at_flippers.com> writes:
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!

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.

"DJ Delorie" <dj_at_delorie.com> wrote in message
news:xnbov1emf7.fsf_at_delorie.com...

John Robertson <spam_at_flippers.com> writes:
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!

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.

"Ian Field" <gangprobing.alien_at_ntlworld.com> schreef in bericht
news:OZw8q.4866$4X4.3867_at_newsfe27.ams2...

"DJ Delorie" <dj_at_delorie.com> wrote in message
news:xnbov1emf7.fsf_at_delorie.com...

John Robertson <spam_at_flippers.com> writes:
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!

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.


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

"petrus bitbyter" <petrus.bitbyter_at_hotmail.com> wrote in message
news:4e640242$0$5077$e4fe514c_at_dreader17.news.xs4all.nl...

"Ian Field" <gangprobing.alien_at_ntlworld.com> schreef in bericht
news:OZw8q.4866$4X4.3867_at_newsfe27.ams2...

"DJ Delorie" <dj_at_delorie.com> wrote in message
news:xnbov1emf7.fsf_at_delorie.com...

John Robertson <spam_at_flippers.com> writes:
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!

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.


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


Most of the external microcode units I've seen had piggyback receptacles
on top the CPU for plugging a ROM into.

"Ian Field" <gangprobing.alien_at_ntlworld.com> schreef in bericht
news:XF19q.122$ox5.46_at_newsfe12.ams2...

"petrus bitbyter" <petrus.bitbyter_at_hotmail.com> wrote in message
news:4e640242$0$5077$e4fe514c_at_dreader17.news.xs4all.nl...

"Ian Field" <gangprobing.alien_at_ntlworld.com> schreef in bericht
news:OZw8q.4866$4X4.3867_at_newsfe27.ams2...

"DJ Delorie" <dj_at_delorie.com> wrote in message
news:xnbov1emf7.fsf_at_delorie.com...

John Robertson <spam_at_flippers.com> writes:
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!

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.


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


Most of the external microcode units I've seen had piggyback receptacles
on top the CPU for plugging a ROM into.


I know them too but the processors I'm talking about are build of bitslices
or lower intergrated logic. They're not only pre PC but even pre micro.

petrus bitbyter

DJ Delorie wrote:

The pinout is as follows:


A0 2 23 D0
A8 10 15 A10

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.

On Thu, 01 Sep 2011 10:03:44 -0700, John Robertson <spam_at_flippers.com
put finger to keyboard and composed:


DJ Delorie wrote:


The pinout is as follows:


A0 2 23 D0
A8 10 15 A10


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.


11 address bits makes them 2K x 8 parts.

- Franc Zabkar
I should go through my stuff and sell off the ROM/EEROMS I have from

mzenier_at_eskimo.com (Mark Zenier) writes:
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.

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

Looking in my 1975 National Memory book I find the 24 pin
MM4214/MM5214 (512 X has a similar power layout (+5 & -12) with no
ground/common connection! The book doesn't show the wiring, but does
say the PMOS device as directly connected to TTL devices and each line
has a 10pf cap.