HARRIS 7611's

From: Bob Shannon <bshannon_at_tiac.net>
Date: Wed Jul 24 08:19:01 2002

Its not quite that simple Tony!

We have used 82S129's from Jameco with a Xeltek SuperPro III and
discovered many strange
facts about old bipolar ROM's.

Our first order arrived with 5 parts, one 74S287A and four 82S129A's.
 The Xeltek lists each of
these parts, as well as the other (Harris and MMI?) manufactuers
seperately. These were ordered
as 74S287's.

The 74S287A worked fine, but several of the 82S129A's died in the burner
before I discovered the
settings that would get them to program and verify corretly. These then
also worked fine as boot ROM's
in the HP1000 CPU's.

Needing more ROM's, I re-ordered and learned that the 74S287 part number
was discontinued, and
they offered 82S129A's as compatible parts. Ok, they worked before, so
why not...

The new order of 5 82S129A arrived, but were from a different
manufactuer. Again several died in
the burner until I found the settings that would get these to program
and verify in the programmer.

With a few parts left, I programed and verifed several copies of an HP
boot loader (for CS/80 drives)
and all verifed correctly. However NONE of these roms will load good
data into the HP-1000 CPU.
The data loaded into memory is all 1's.

So once programed, reading is not fully compatible from device to device
due to access speeds, circuit
loading, and maybe the phase of the moon as well.

These ROM's that load all 1's still verify in a programmer.

Now I do admit the Xeltek programmer is not one of the best out there,
but this is clearly a real device
compatibility issue.

Steve has some Harris parts in hand, and we know that ROM is used by HP,
so they should work fine
as boot loaders (HP also used 82S129's, but not 82S129A's it seems).
 All thats needed is someone with
a programmer who can duplicate some existing ROM's in-hand.

Tony Duell wrote:

>>Hey guys,
>>I need another set of BOOT ROMS for a HP1000 and cannot find a burner for=
>>those devices. Does anyone have the resources (burner) to duplicate HARRI=
>Do you need them to be Harris parts? (do you have blank Harris 7611s?)
>According to my databooks, the 7611 is a 256*4 PROM, equivalent _for
>reading_ to the 74S287, etc.
>Many manufactuers made those under a variety of numbers (Signetics 82S129
>is probably the easiest to find). They are all essentially equivalent for
>reading (which is all the HP1000 cares about), but have different
>programming algorithms (some manufacturers published these, others
>I would suggest seeing which blanks you can find first (these chips are
>most certainly one-time-programmable only!), then find a programmer that
>can handle them.

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Received on Wed Jul 24 2002 - 08:19:01 BST

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