weird old ROM chips...

[Ian Field]

"petrus bitbyter" <petrus.bitbyter@hotmail.com> wrote in message
news:4e640242$0$5077$e4fe514c@dreader17.news.xs4all.nl...

"Ian Field" <gangprobing.alien@ntlworld.com> schreef in bericht
news:OZw8q.4866$4X4.3867@newsfe27.ams2...

"DJ Delorie" <dj@delorie.com> wrote in message
news:xnbov1emf7.fsf@delorie.com...

John Robertson <spam@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.

 

[petrus bitbyter]

"Ian Field" <gangprobing.alien@ntlworld.com> schreef in bericht
news:XF19q.122$ox5.46@newsfe12.ams2...

"petrus bitbyter" <petrus.bitbyter@hotmail.com> wrote in message
news:4e640242$0$5077$e4fe514c@dreader17.news.xs4all.nl...

"Ian Field" <gangprobing.alien@ntlworld.com> schreef in bericht
news:OZw8q.4866$4X4.3867@newsfe27.ams2...

"DJ Delorie" <dj@delorie.com> wrote in message
news:xnbov1emf7.fsf@delorie.com...

John Robertson <spam@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

 

[josephkk]

On Mon, 5 Sep 2011 14:45:10 +0200, "petrus bitbyter"
<petrus.bitbyter@hotmail.com> wrote:

"Ian Field" <gangprobing.alien@ntlworld.com> schreef in bericht
news:XF19q.122$ox5.46@newsfe12.ams2...

"petrus bitbyter" <petrus.bitbyter@hotmail.com> wrote in message
news:4e640242$0$5077$e4fe514c@dreader17.news.xs4all.nl...

"Ian Field" <gangprobing.alien@ntlworld.com> schreef in bericht
news:OZw8q.4866$4X4.3867@newsfe27.ams2...

"DJ Delorie" <dj@delorie.com> wrote in message
news:xnbov1emf7.fsf@delorie.com...

John Robertson <spam@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

Ah yes, 2900 (TTL), COSMAC, and the likes. And there were a lot of
hybrids as well with the micro doing the "slow" stuff.

?-)

 

[Franc Zabkar]

On Thu, 01 Sep 2011 10:03:44 -0700, John Robertson <spam@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
--
Please remove one 'i' from my address when replying by email.

 

[Jamie]

Franc Zabkar wrote:

On Thu, 01 Sep 2011 10:03:44 -0700, John Robertson <spam@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

yesteryears.

Jamie

 

[John Robertson]

DJ Delorie wrote:

mzenier@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

Ah, 2K X 8...how did I miss that? OK, if you can find the Mostek 1975
PROM manual it covers the Mostek MK28000 which is a PMOS device using
-12/+5 and might well be similar or the same as yours.

Best guess for part numbers are:

EA4900C or EA4900L

Signetics has a PMOS 2K X 8 #2580 that might be close too...

Looking in my 1975 National Memory book I find the 24 pin MM4214/MM5214
(512 X 8) 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.

John :-#)#

--
(Please post followups or tech enquiries to the newsgroup)
John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9
Call (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com
"Old pinballers never die, they just flip out."

 

[DJ Delorie]

John Robertson <spam@flippers.com> writes:

Looking in my 1975 National Memory book I find the 24 pin
MM4214/MM5214 (512 X 8) 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.

Weird. More chips I can't find specs for