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Roland Huisman
December 20th, 2014, 01:19 PM
Hello everyone,

I have this Lear Siegler ADM-1A terminal.
http://terminals.classiccmp.org/wiki/index.php/Lear_Siegler_ADM-1A
(This is actually my terminal on these pictures)

Some idiot has flipped over the PROMs in the past. Probably tried to fix the terminal
and put them back in in the wrong way. So they had 5V on the GND and vice versa...
I'm afraid the ROMs are damaged due this action. Does anyone have the ROM images for this terminal?

The terminal does not run at all. It displays the current state of the display ram.
If I trigger the write line of the RAM chips all characters become the same.
(It just copies the actual bus state to all the ram locations.)

If I remove only one of the two PROMs the terminal begins to beep at random moments
and there is actually some random data on the bus... when I put in the second eprom
all bus lines are pulled to zero and the PROM isn't even selected by the CS of the prom.

So I'm really afraid the ROMs are more or less killed.

If I had only the data, even written on paper. Then I could make my own new ROMs for it.

Thanks in advance!
Regards, Roland

Roland Huisman
December 20th, 2014, 02:23 PM
Oh I see there are several PROM listings in the manual! (page 50 in acrobat / 4-15 in the document)
http://manx.classiccmp.org/details.php/11,5616

So this should make it possible to make my own PROMs.
There is a N82S115N and a N82S114N PROM in the terminal.
Does anyone know an good alternative for these? I don't thing
I would find these in blank condition anymore...


Regards, Roland

Al Kossow
December 20th, 2014, 02:40 PM
Oh I see there are several PROM listings in the manual! (page 50 in acrobat / 4-15 in the document)
http://manx.classiccmp.org/details.php/11,5616

So this should make it possible to make my own PROMs.
There is a N82S115N and a N82S114N PROM in the terminal.
Does anyone know an good alternative for these? I don't thing
I would find these in blank condition anymore...


Regards, Roland

the 115 is a prom/latch combo.

g4ugm
December 20th, 2014, 02:49 PM
They are 60ns Schotkey so if you need 60ns ROMs you are going to need fast one...

gslick
December 20th, 2014, 04:30 PM
http://store.americanmicrosemiconductor.com/n82s114n.html
N82S114N - In Stock 15 Brand New Available from $ 5.69

Roland Huisman
December 21st, 2014, 02:37 AM
Hello, thanks for the help!

So there are still new ones available! That is good news!

The schematics shows 8204 memory chips. Don't know the full number of these.
But the terminal supports a maximum of 2Kbit. (only 8 address lines are connected)

The software listing goes up to 377 oct. Also 2Kbit. So the N82S115N
(which is 4Kbit) in the terminal has twice the size of which is supported.
The N82S114N is enough for both of the proms.

( Pin 3 is not connected in the terminal. This pin is the extra address line on the 115)

So I have to buy a few of these proms and make a program adapter for it!
They need a weird 17V as program voltage.

Corey986
December 21st, 2014, 02:52 AM
For programming, track down a dataIO 29B with unpack. It should be able to program it easily.

Roland Huisman
December 27th, 2014, 09:47 AM
Hello Corey986,

I found two people which told me they have a programmer which
supports these devices. So there is hope for me :D

So now I have to buy a few chips and retype the programs.

Regards, Roland

jdreesen
October 1st, 2018, 10:36 PM
I read out these roms and have send Roland the binaries. Anyone else needs these ?

Jos