22 May
2000
22 May
'00
1:33 p.m.
> The 8101 dual-port 256bx4 RAM is no longer
available, but Jameco has a
5101
which looks
like a likely sub.
Check the timing specs; the 5101 might be slower.
Also, 8101 is just a different marketing designation for 2101, just like
8702 for 1702, etc. The 2101 should be easier to find.
Apparently Intel's marketing people didn't think that engineers would be
able to figure out that their standard RAM, ROM, PROM, and EPROM
products would work with the 8080, so they introduced 8xxx-series part
numbers for them.
No, not quite. It was a marketing thing to "bundle" parts with like numbers
to indicate compatability for sales. The best of those was the 8205 that
was really a 74138 but intel kept claiming it was a similar but gltich free
part. I cracked one open to prove a point and th intel part was a TI 74138
die. Kitting, the name used by those in the trade back then was intels way
of insuring they didn't get cherry picked for the 8224 and 8212 while AMD
got the 8080 order along with someone else getting the ram order.
Allison
23 May
23 May
9:38 a.m.
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3:06 p.m.
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
Now that's interesting. When I got my (second-hand) Intellec MCS8i, it
didn't work. One of the faults was soon traced to an 8205 chip on (IIRC)
one of the memory boards.
At the time I'd never heard of this device (and didn't have a suitable
Intel databook), but from the schematics in the manual it appeared to
have the same pinout as an 74LS138. So I stuck one of those in and of
course it worked fine (and still works AFAIK).
I wondered at the time what the difference was between an 8205 and a
74LS138. Now I know...
-tony
Hi Tony
As I recall, the difference was that the Intel parts could
stand a much lower negative voltage ( -10V? ) than the general purpose
TTL. This made is compatible with the 8080's. Also, as
I recall, the 8205 were also Schottky's.
Dwight
4:19 p.m.
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6:07 p.m.
The propagation delays cited for the three popular bipolar technologies in
which the '138 was offered seem to vary pretty widely. My experience has
been that these spec's reflect worst-case conditions: conditions more
frequently encountered then than now, since it was likely a designer in '76
or so would be using two levels of these decoders on a memory board, one to
select a bunch of memories, and one to select a bunch of '138's that
selected the memories. Back when small (1K-bit) memories were the most
common sort, there were lots of chips expecting to see that select strobe,
and the worst case load made the prop-delay long.
When there's only a single 2764 to drive, the difference between the three
available technologies is much smaller. A fairly typical memory
configuration might have been a bank of 72 2102's (they liked parity back
then) and about eight 1702's. One 138 would drive each of the rows of RAMs,
while another drove each of the 8 1702's. That's lots of capacitance, not
to mention a fair DC load. I'd say the difference between STTL and standard
TTL would have shown up there in the form of a difference of maybe 15-25 ns.
Due to the size of memory devices back then, the decoding tree would have
been pretty long, therefore combining the delay through several decoders.
This would probably have been a depth of two in the case of the memory
layout I suggested. 2102's back then had a typical access time of 600 ns
and 1702's were somewhere between 750 and 1000 nanoseconds. I don't think
one could claim that 50 ns is negligible with a 2 MHz 8080 under those
conditions.
Dick
----- Original Message -----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, May 23, 2000 7:19 PM
Subject: Re: Re[2]: Altair parts substitutions
TTL. This made is compatible with the 8080's.
Also, as
_Apart_ from the clock lines (and power supplies :-)), I thought all pins
on the 8080 were at standard TTL levels. Certainly the address bus was,
which is where you'd be most likely to use a 3-8 decoder.
I recall, the 8205 were also Schottky's.
Possibly, But whether it's a 74138, 74S138 or 74LS138 makes little
difference on the average 8080 system memory board...
Dwight
-tony
24 May
24 May
3:45 a.m.
select a bunch of memories, and one to select a bunch
of '138's that
selected the memories. Back when small (1K-bit) memories were the most
common sort, there were lots of chips expecting to see that select strobe,
and the worst case load made the prop-delay long.
Compared to the typical 500-650ns prop delay of common memories back in
1976 teh prop delay of the '138 was relatively short.
configuration might have been a bank of 72 2102's
(they liked parity back
then) and about eight 1702's. One 138 would drive each of the rows of RAMs,
I found it to be rare except in mainframes and then it was usually 4kx1
parts which were common and available.
layout I suggested. 2102's back then had a
typical access time of 600 ns
and 1702's were somewhere between 750 and 1000 nanoseconds. I don't think
one could claim that 50 ns is negligible with a 2 MHz 8080 under those
conditions.
It was. The 2102s were fast enough to run with no waits but 1702s were so
slow another 50ns was nothing as waits were added in 500ns increments.
By 1977 the 1702 was long gone and nearly history for anything other than
hobby and existing production and the 2508/2716 were moving in fast
with a 450ns Tacc.
Allison
6:23 a.m.
You missed my point, Allison. What I hoped you'd get from that message was
that there were MANY parts involved in even a small memory array, which
meant a longer decoder tree than what we'd use today, or even 15 years ago.
Since the specified prop-delay is on the order of 35 ns, multiplied by two
or three, the difference between the TTL parts at nominally 25 extra ns of
prop delay per decoder, the prop-delay difference is significant, and it's
especially so in the context of the slow memory devices of the time. If
there were only a 250 ns access time for memory devices, it would have been
insignificant because it consumed a small part of a large window. In this
case, however it consumed a large part of what was left of the window after
the access time was deducted from the window.
I've embedded a few remarks below, too.
Dick
----- Original Message -----
From: <allisonp(a)world.std.com To:
<classiccmp(a)classiccmp.org Sent: Wednesday, May
24, 2000 6:45 AM
Subject: Re: Re[2]: Altair parts substitutions
back
That, precisely was the critical factor. Nobody wanted to run with more
waits than absolutely necessary.
In '77, Intel's boards were shipped
populated with 2708's. I bought lots of
their boards and even more of the EPROMS. 2102's were typically 600 ns,
while the 21L02's, which were easier on the power budget, were quite
expensive by comparison. This had changed significantly by late '78, as had
the TTL market, but 450ns 21L02's weren't the fastest available. They were
just what Intel shipped. That year Intel started shipping their 8020-4
boards which were the first ones I got with the 8080-A and 2708's in
combination with 2114's. These were 450 ns parts. Within a year, they had
shifted to an 8085 board numberd iSBC-8024 which used 8708's (just 5-volt
2708's) and those really silly 8185's which were srams with multiplexed
address/data inputs compatible with the 8085's timing. By that time I
decided to quit using Intel SBC's.
> Allison
> select a bunch of memories, and one to select a
bunch of '138's that
> selected the memories. Back when small (1K-bit) memories were the most
> common sort, there were lots of chips expecting to see that select
strobe,
and the worst
case load made the prop-delay long.
Compared to the typical 500-650ns prop delay of common memories back in
1976 teh prop delay of the '138 was relatively short.
> configuration might have been a bank of 72 2102's (they liked parity > then) and about eight 1702's. One 138 would
drive each of the rows of
RAMs,
I found it to be rare except in mainframes and then it was usually 4kx1
parts which were common and available.
In '77 I read one memorable article in which an IBM exec was complaining
that they couldn't get enough of the 4kx1 i2147's (55 ns, 70 ns, 120 ns) to
meet their needs. It was a couple of years yet, before we small users could
even get the TI 4044, NS 5257, or i2141. They were still pretty costly in
'79.
> layout I suggested. 2102's back then had a typical access time of 600
ns
> and 1702's were somewhere between 750 and
1000 nanoseconds. I don't
think
one could
claim that 50 ns is negligible with a 2 MHz 8080 under those
conditions.
It was. The 2102s were fast enough to run with no waits but 1702s were so
slow another 50ns was nothing as waits were added in 500ns increments.
By 1977 the 1702 was long gone and nearly history for anything other than
hobby and existing production and the 2508/2716 were moving in fast
with a 450ns Tacc.
Yes, but ... the 5-volt parts were costing on the order of $100 per piece.
I bought a bunch for a project and still remember the "sticker-shock,"
though it wasn't any better a year later when I had to buy 2732's. In the
latter case, I sold them for $25 each to a west-coast surplus vendor who
turned around and sold them for $80 each.
7:33 a.m.
On Wed, 24 May 2000, Richard Erlacher wrote:
You missed my point, Allison. What I hoped you'd
get from that message was
that there were MANY parts involved in even a small memory array, which
meant a longer decoder tree than what we'd use today, or even 15 years ago.
Since the specified prop-delay is on the order of 35 ns, multiplied by two
Ok, for the reading impaired. For a memeory system of those speeds 25ns is
NOTHING or functionally close to it. The average S100 card
was 32 or 64 2012s and most managed despite thge slow ttl and memories
to hit the required speed for 8080 quite easily even with two layers
of 74138 plus 7483s for mapping segments.
Allison
or three, the difference between the TTL parts at
nominally 25 extra ns of
prop delay per decoder, the prop-delay difference is significant, and it's
especially so in the context of the slow memory devices of the time. If
there were only a 250 ns access time for memory devices, it would have been
insignificant because it consumed a small part of a large window. In this
case, however it consumed a large part of what was left of the window after
the access time was deducted from the window.
I've embedded a few remarks below, too.
Dick
----- Original Message -----
From: <allisonp(a)world.std.com>
To: <classiccmp(a)classiccmp.org>
Sent: Wednesday, May 24, 2000 6:45 AM
Subject: Re: Re[2]: Altair parts substitutions
back
That, precisely was the critical factor. Nobody wanted to run with more
waits than absolutely necessary.
In '77, Intel's boards were
shipped populated with 2708's. I bought lots of
their boards and even more of the EPROMS. 2102's were typically 600 ns,
while the 21L02's, which were easier on the power budget, were quite
expensive by comparison. This had changed significantly by late '78, as had
the TTL market, but 450ns 21L02's weren't the fastest available. They were
just what Intel shipped. That year Intel started shipping their 8020-4
boards which were the first ones I got with the 8080-A and 2708's in
combination with 2114's. These were 450 ns parts. Within a year, they had
shifted to an 8085 board numberd iSBC-8024 which used 8708's (just 5-volt
2708's) and those really silly 8185's which were srams with multiplexed
address/data inputs compatible with the 8085's timing. By that time I
decided to quit using Intel SBC's.
> Allison
> select a bunch of memories, and one to
select a bunch of '138's that
> selected the memories. Back when small (1K-bit) memories were the most
> common sort, there were lots of chips expecting to see that select
strobe,
and the
worst case load made the prop-delay long.
Compared to the typical 500-650ns prop delay of common memories back in
1976 teh prop delay of the '138 was relatively short.
> configuration might have been a bank of 72 2102's (they liked parity > then) and about eight 1702's. One 138
would drive each of the rows of
RAMs,
I found it to be rare except in mainframes and then it was usually 4kx1
parts which were common and available.
In '77 I read one memorable article in which an IBM exec was complaining
that they couldn't get enough of the 4kx1 i2147's (55 ns, 70 ns, 120 ns) to
meet their needs. It was a couple of years yet, before we small users could
even get the TI 4044, NS 5257, or i2141. They were still pretty costly in
'79.
> layout I suggested. 2102's back then had a typical access time of 600
ns
> and 1702's were somewhere between 750
and 1000 nanoseconds. I don't
think
one could
claim that 50 ns is negligible with a 2 MHz 8080 under those
conditions.
It was. The 2102s were fast enough to run with no waits but 1702s were so
slow another 50ns was nothing as waits were added in 500ns increments.
By 1977 the 1702 was long gone and nearly history for anything other than
hobby and existing production and the 2508/2716 were moving in fast
with a 450ns Tacc.
Yes, but ... the 5-volt parts were costing on the order of $100 per piece.
I bought a bunch for a project and still remember the "sticker-shock,"
though it wasn't any better a year later when I had to buy 2732's. In the
latter case, I sold them for $25 each to a west-coast surplus vendor who
turned around and sold them for $80 each.
7:45 a.m.
"Richard Erlacher" <richard(a)idcomm.com> wrote:
Hi
I find it interesting that after the 2716's were out for a while,
and the price had dropped to someplace in the $5-$10 range someplace,
the intel 2508's were still in the high $30's. This always
amused me because there was no difference at all between the
Intel 2716 and the 2508 other than the 2508 was a half bad
2716. I call that real good sales to take bad parts and get
more for them. Intel had done this relabel trick because
TI was taking their 2708 sales with their real 2508. When working
at Intel, we used to get may of the dropout parts to use
in our test kludges. We would test the 2508's to see what
was bad in the other half and often, if the bad bits were
not an issue, we would used them in place of 2716's.
I may be incorrect about the 8205 having the negative input
voltage. I was thinking about the 8212's that do have extended
input voltage. It has been a long time since I was working
with these things and much has gotten foggy.
I don't remember exactly when 74S138's were first introduced
relative to 8205's. I think that is may just have been an
issue of the 74S138's were not in full production when
Intel was designing things to work with their memories.
By the time products were out, they may have seemed to be
used at about the same time but when designing, you need to be
a little ahead.
Dwight
By 1977 the 1702 was long gone and nearly history for anything other than
hobby and existing production and the 2508/2716 were moving in fast
with a 450ns Tacc.
Yes, but ... the 5-volt parts were costing on the order of $100 per piece.
I bought a bunch for a project and still remember the "sticker-shock,"
though it wasn't any better a year later when I had to buy 2732's. In the
latter case, I sold them for $25 each to a west-coast surplus vendor who
turned around and sold them for $80 each.
>
9:19 a.m.
New subject: Shurgart drive question
Hi
I'm still working no my NIC-80. I'm having a data pattern
sensitive problem. I'm not yet sure if it is in the SA900
drive or in the controller. When looking at the drive,
there is a clock/data separator circuit. It uses two one shots.
One is for the next clock cycle after a one was read and
one is for the next clock cycle if there was no one read.
I understand the issues of this shifting of the read
data but I don't know how much these two one shots need
to be adjusted. The SA800 TTL board also has the same circuit.
I was hoping that someone with an old drive could put
a 'scope on these two one shots and determine the nominal
pulse widths they see? The test points are labled the same
on both the SA900 and SA800 series drives as TP21 and TP24.
They are negative going pulses.
Dwight
10:08 a.m.
New subject: Looking for motherboard and wiring info for Lisa 1
I just picked up a non-functioning Lisa 2 (which was an upgraded Lisa 1) and
have lots of technical documentation, but nothing on the motherboard and
wiring between powersupply, video and motherboard/cage assembly. I'd like
to avoid tracing it all out if this info is available.
The Lisa won't power up when I press the power switch (the power switch and
both the front and back safety switches have checked out OK) and I'm
attempting to locate that problem.
Also, it appears that one 120 pin socket on the motherboard is missing a
connector pin, and there is some amount of blue corrosion on the tops of the
other connectors. What's the best way to clean off this kind of (light)
corrosion (oxidation)?
It appears to me that the motherboard socket that is missing one pin will
need to be replaced. Anybody have any recommendations on how to best do
this? The motherboard is a four layer board. I have soldering/desoldering
experience, but I've never tackled an item with this many pins on a 4 layer
board before.
John Lewczyk
11:16 a.m.
New subject: Looking for motherboard and wiring info for Lisa 1
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8:18 p.m.
New subject: Looking for motherboard and wiring info for Lisa 1
-> > It appears to me that the motherboard socket that is missing
-> > one pin will need to be replaced. Anybody have any recommendations on
how
-> > to best do this? The motherboard is a four layer board. I have
-> > soldering/desoldering experience, but I've never tackled an item with
this many pins
-> > on a 4 layer board before.
->
-> Assuming the old connector is worthless (or at least worth a lot less
-> than the motherboard), I'd recommend breaking it up and removing it in
-> sections.
->
-> Sometimes you can cut away the plastic _carefully_ (you don't want to
-> damage any tracks on the board). More often, if you heat the pin
-> from the
-> solder side of the board you can pull it out on the component side --
-> right out of the plastic housing (which will melt slightly from
-> the heat).
->
-> Once you've got all the pins out and the housing removed, then melt the
-> solder in each hole with the iron from one side of the board and
-> suck out
-> the solder (with a solder sucker or 'Soldapulit' (IIRC)) from the other.
-> Put the new connector in place and resolder it.
->
-> If you can get a spare pin of the right size you _might_ be able to
-> remove the broken pin only, clean out the solder from the 'back' of the
-> board and put a new pin in place, leaving the rest of the pins (and
-> connector housing) alone. I've done it a couple of times
My thoughts exactly. Of course the broken one can't be grasped and pulled
through if it is broken off flush with the connector, but it may be able to
be heated and pushed through enough to nab. Barring that, I've used a sharp
stainless steel pick the same diameter of the pins to push pins through
enough to get a hold of them on the connector side. Just heat the pad and
the pin (it help to apply a little extra solder), and once the pin is loose
in the hole gently push the pin. Sometimes it also helps to trim the solder
side of the pin flat so the pick won't slide off. Once the broken pin is
out, remove one from another connector by pulling it out. A little heat may
make the job easier if it is stubborn. Then, assuming the pin hole has been
cleaned of solder, push in the replacement pin and resolder it. This is
always much easier, IMHO, than replacing an entire connector for just one
broken pin.
Bill
->
-> -tony
->
25 May
25 May
9:45 a.m.
New subject: Looking for motherboard and wiring info for Lisa 1
On Wed, 24 May 2000, John Lewczyk wrote:
I just picked up a non-functioning Lisa 2 (which was
an upgraded Lisa 1) and
have lots of technical documentation, but nothing on the motherboard and
wiring between powersupply, video and motherboard/cage assembly. I'd like
to avoid tracing it all out if this info is available.
The Lisa/Macintosh XL Do-it-yourself Guide has some good data on the Lisa,
but no schematics. I believe I have technical data on the Lisa, but it's
buried :(
Also, it appears that one 120 pin socket on the
motherboard is missing a
connector pin, and there is some amount of blue corrosion on the tops of the
other connectors. What's the best way to clean off this kind of (light)
corrosion (oxidation)?
The blue corrosion is usually caused by the clock battery on the main
board (the one you see when you open up the back) that goes bad and leaks
all over the damn place. Some good suggestions have come up in the past
regarding cleaning it up, so I'll let the experts chime in (I know I have
that info saved somewhere).
It appears to me that the motherboard socket that is
missing one pin will
need to be replaced. Anybody have any recommendations on how to best do
this? The motherboard is a four layer board. I have soldering/desoldering
experience, but I've never tackled an item with this many pins on a 4 layer
board before.
Find another Lisa :) and use it for parts.
Sellam International Man of Intrigue and Danger
-------------------------------------------------------------------------------
Looking for a six in a pile of nines...
Coming soon: VCF 4.0!
VCF East: Planning in Progress
See http://www.vintage.org for details!
3:10 p.m.
New subject: Looking for motherboard and wiring info for Lisa 1
On Thu, 25 May 2000, Vintage Computer GAWD! wrote:
The Lisa/Macintosh XL Do-it-yourself Guide has some
good data on the Lisa,
but no schematics. I believe I have technical data on the Lisa, but it's
buried :(
Duh, a URL would've been nice:
http://www.cs.dartmouth.edu/~woz/lisatech/
Sellam International Man of Intrigue and Danger
-------------------------------------------------------------------------------
Looking for a six in a pile of nines...
Coming soon: VCF 4.0!
VCF East: Planning in Progress
See http://www.vintage.org for details!
24 May
24 May
3:22 p.m.
New subject: Shurgart drive question
Are you using a controller that requires the external "data separator" on
the drive? If you use it with a controller that expects the raw data you'll
get something that works part of the time. One might interpret that as
being pattern-sensitive, since it is.
I'm not sure you need to fiddle with this data separator much, but if you
take into consideration that what most folks call a "data separator" is
really a clock extractor, which is little else than a missing clock detector
and fills in the missing clocks for the benefit of the data extraction logic
in the controller.
Why not contact me off-list and I'll look up what I can from the drive
documents.
What troubles me is that I don't know what kind of controller you're using,
hence I dont know that this mechanism on the drive is even required for it.
Are you sure you need this crude bit of circuitry?
Dick
----- Original Message -----
From: Dwight Elvey <elvey(a)hal.com>
To: <classiccmp(a)classiccmp.org>
Sent: Wednesday, May 24, 2000 12:19 PM
Subject: Shugart drive question
Hi
I'm still working on my NIC-80. I'm having a data pattern
sensitive problem. I'm not yet sure if it is in the SA900
drive or in the controller. When looking at the drive,
there is a clock/data separator circuit. It uses two one shots.
One is for the next clock cycle after a one was read and
one is for the next clock cycle if there was no one read.
I understand the issues of this shifting of the read
data but I don't know how much these two one shots need
to be adjusted. The SA800 TTL board also has the same circuit.
I was hoping that someone with an old drive could put
a 'scope on these two one shots and determine the nominal
pulse widths they see? The test points are labled the same
on both the SA900 and SA800 series drives as TP21 and TP24.
They are negative going pulses.
Dwight
23 May
23 May
5:53 p.m.
All this verbage about the i8205 has forced me to dig out an old
(pre-Columbian) data book. IIRC Intel really didn't make any of its TTL
parts, as their fab was dedicated to PMOS, NMOS, and later, CMOS devices.
Therefore I'd suspect that the i8205 (and also the i3205) were strictly TTL,
or, more correctly, schottky TTL. The i8205, by the way, sinks only 10 mA
as opposed to the schottky equivalent, the 'S138, which sinks somewhere
between 16 and 24 mA, depending on whose databook of that day you consult.
This was probably more specsmanship than technology, however.
I do, however, believe that applying a negative voltage lower than -0.6
volts would cause damage. The 1978 datasheet says very little about that.
I'm sure there's a better reference, but I'm too lazy to dig for it in the
basement. I can see no reason why one would wish to apply a negative
voltage to one of these babies, however, since the only parts from the '70's
that needed that negative voltage were the PMOS and a few NMOS memories,
which, admittedly could fail in some mode that might short the Vbb supply to
the select logic, though that's highly unlikely. Parts normally aren't
designed with unusual failure modes of other components taken into
consideration. In any event I'm unable to find any spec indicating the
device will tolerate any signal more negative than a silicon diode forward
voltage below its own GND.
Dick
----- Original Message -----
From: Dwight Elvey <elvey(a)hal.com>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, May 23, 2000 6:06 PM
Subject: Re[2]: Altair parts substitutions
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
Now that's interesting. When I got my (second-hand) Intellec MCS8i, it
didn't work. One of the faults was soon traced to an 8205 chip on (IIRC)
one of the memory boards.
At the time I'd never heard of this device (and didn't have a suitable
Intel databook), but from the schematics in the manual it appeared to
have the same pinout as an 74LS138. So I stuck one of those in and of
course it worked fine (and still works AFAIK).
I wondered at the time what the difference was between an 8205 and a
74LS138. Now I know...
-tony
Hi Tony
As I recall, the difference was that the Intel parts could
stand a much lower negative voltage ( -10V? ) than the general purpose
TTL. This made is compatible with the 8080's. Also, as
I recall, the 8205 were also Schottky's.
Dwight
24 May
24 May
3:39 a.m.
(pre-Columbian) data book. IIRC Intel really
didn't make any of its TTL
parts, as their fab was dedicated to PMOS, NMOS, and later, CMOS devices.
Therefore I'd suspect that the i8205 (and also the i3205) were strictly TTL,
or, more correctly, schottky TTL. The i8205, by the way, sinks only 10 mA
as opposed to the schottky equivalent, the 'S138, which sinks somewhere
between 16 and 24 mA, depending on whose databook of that day you consult.
This was probably more specsmanship than technology, however.
My intel data book set for the 1974-1981 window is fairly complete and the
I8205 has the exact same specs ans the TI LS138. Intel did have bipolar
fab back then and parts they did there included things like 3212, 300x,
8216/8126, 8224, 8228/38, an assortment of Bipolar PROMs and later part
like 8282, 8283, 8219, 8284, 8284A and others. Their capability is limted
so they did farm out stuff (under license) to TI and AMD.
Allison
5:55 a.m.
Are you sure about that, Allison? I recall popping the lid off a
ceramic-packaged Intel labelled 28-pin logic device back in the '70's and
finding it housed a die clearly marked NS (under a microscope). In another
case, it was a PROM and clearly marked with Signetics' logo on the die.
Dick
----- Original Message -----
From: <allisonp(a)world.std.com>
To: <classiccmp(a)classiccmp.org>
Sent: Wednesday, May 24, 2000 6:39 AM
Subject: Re: Re[2]: Altair parts substitutions
> (pre-Columbian) data book. IIRC Intel really
didn't make any of its TTL
> parts, as their fab was dedicated to PMOS, NMOS, and later, CMOS
devices.
> Therefore I'd suspect that the i8205 (and
also the i3205) were strictly
TTL,
> or, more correctly, schottky TTL. The i8205, by
the way, sinks only 10
mA
> as opposed to the schottky equivalent, the
'S138, which sinks somewhere
> between 16 and 24 mA, depending on whose databook of that day you
consult.
This was
probably more specsmanship than technology, however.
My intel data book set for the 1974-1981 window is fairly complete and the
I8205 has the exact same specs ans the TI LS138. Intel did have bipolar
fab back then and parts they did there included things like 3212, 300x,
8216/8126, 8224, 8228/38, an assortment of Bipolar PROMs and later part
like 8282, 8283, 8219, 8284, 8284A and others. Their capability is limted
so they did farm out stuff (under license) to TI and AMD.
Allison
7:29 a.m.
On Wed, 24 May 2000, Richard Erlacher wrote:
Are you sure about that, Allison? I recall popping
the lid off a
ceramic-packaged Intel labelled 28-pin logic device back in the '70's and
finding it housed a die clearly marked NS (under a microscope). In another
case, it was a PROM and clearly marked with Signetics' logo on the die.
Yes, and so? It conforms with what I said. Now was that 28 pin device
one of those listed?
Also Nec made MOS devices for intel Namely 8274 and 8272 as well.
Allison
Dick
----- Original Message -----
From: <allisonp(a)world.std.com>
To: <classiccmp(a)classiccmp.org>
Sent: Wednesday, May 24, 2000 6:39 AM
Subject: Re: Re[2]: Altair parts substitutions
> (pre-Columbian) data book. IIRC Intel
really didn't make any of its TTL
> parts, as their fab was dedicated to PMOS, NMOS, and later, CMOS
devices.
> Therefore I'd suspect that the i8205
(and also the i3205) were strictly
TTL,
> or, more correctly, schottky TTL. The
i8205, by the way, sinks only 10
mA
> as opposed to the schottky equivalent, the
'S138, which sinks somewhere
> between 16 and 24 mA, depending on whose databook of that day you
consult.
This was
probably more specsmanship than technology, however.
My intel data book set for the 1974-1981 window is fairly complete and the
I8205 has the exact same specs ans the TI LS138. Intel did have bipolar
fab back then and parts they did there included things like 3212, 300x,
8216/8126, 8224, 8228/38, an assortment of Bipolar PROMs and later part
like 8282, 8283, 8219, 8284, 8284A and others. Their capability is limted
so they did farm out stuff (under license) to TI and AMD.
Allison
8820
days inactive
8823
days old
19 comments
7 participants
participants (7)
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allisonp＠world.std.com -
ard＠p850ug1.demon.co.uk -
elvey＠hal.com -
foo＠siconic.com -
jlewczyk＠his.com -
richard＠idcomm.com -
whdawson＠mlynk.com