5 Aug
2007
5 Aug
'07
5:21 p.m.
Subject: Re: newbie building a scratch-built computer
From: Dave McGuire <mcguire at neurotica.com>
Date: Sun, 05 Aug 2007 14:43:16 -0400
To: "General Discussion: On-Topic Posts Only" <cctech at
classiccmp.org>
On Aug 5, 2007, at 12:17 PM, Chuck Guzis wrote:
Works for me. The larger Eproms like 27128, 27256 and larger
I have loads of from old PCs that were junked. A ready supply
of fast and large (often CMOS) eproms make it easier to do that.
Though I had to mod my Prommer to do parts larger than 27256
the code upgrade was easy.
Allison
For that matter, why bother with UV erasers and
UV EPROMs at all?
Sorry to jump in, but I'd like to add my opinion. I have a few
reasons why someone might use UV EPROMs.
If you've got the right equipment, UV EPROMs are cheap, readily
available, highly standardized, predictable, and generally pretty
bulletproof.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
9 Aug
9 Aug
12:37 p.m.
On 5 Aug 2007 at 17:21, Allison wrote:
Works for me. The larger Eproms like 27128, 27256 and
larger
I have loads of from old PCs that were junked. A ready supply
of fast and large (often CMOS) eproms make it easier to do that.
Though I had to mod my Prommer to do parts larger than 27256
the code upgrade was easy.
...but the OP had neither eraser nor programmer for the things--and
that was my point. Why bother using slow, obsolete parts when there
are better alternatives available?
Cheers,
Chuck
6:26 p.m.
On Aug 9, 2007, at 12:37 PM, Chuck Guzis wrote:
"Better" is debatable...the lack of standardization in the flash
world is one thing that keeps me going back to EPROMs for my
projects. Something doesn't become obsolete just because something
newer is available.
Faster access time than an EPROM isn't going to help the guy much
unless he's working with a really fast processor.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
Works for me.
The larger Eproms like 27128, 27256 and larger
I have loads of from old PCs that were junked. A ready supply
of fast and large (often CMOS) eproms make it easier to do that.
Though I had to mod my Prommer to do parts larger than 27256
the code upgrade was easy.
...but the OP had neither eraser nor programmer for the things--and
that was my point. Why bother using slow, obsolete parts when there
are better alternatives available?
7:44 p.m.
On 9 Aug 2007 at 18:26, Dave McGuire wrote:
"Better" is debatable...the lack of
standardization in the flash
world is one thing that keeps me going back to EPROMs for my
projects. Something doesn't become obsolete just because something
newer is available.
When it's not being designed into new products, wouldn't it be fair
to call it "obsolete"? But my main point is that UV EPROM requires
some specialized tools to erase and program. If I were starting out
from zero, I wouldn't waste my time. Of course, if
the OP is
fascinated by the little quartz window in a DIP or intends to program
a lot of UV EPROM, acquiring the equipment might be worth the
trouble.
If you don't like flash, there are alternatives. FRAM, for example,
is of a size that would adapt very nicely to a "vintage" project. I
believe that 5v DIP-based parts are still available. That might also
conveniently bypass the need for an emulator.
Or just get an EEPROM programmer and forget about the eraser.
Pinouts are reasonably close to UV EPROM in many instances, so if you
wanted to go "authentic", there wouldn't be a problem.
Please note that I've got a couple of programmers as well as an
eraser--and a big pile of EPROMs. I use them. But I don't find it
particularly convenient.
Cheers,
Chuck
10 Aug
10 Aug
2:29 a.m.
On Aug 9, 2007, at 7:44 PM, Chuck Guzis wrote:
Well I guess I define "obsolete" as "useless". That seems to jibe
with the industry definition as well.
"Better" is debatable...the lack of standardization in the flash
world is one thing that keeps me going back to EPROMs for my
projects. Something doesn't become obsolete just because something
newer is available.
When it's not being designed into new products, wouldn't it be fair
to call it "obsolete"? But my main point is that UV EPROM requires
some specialized tools to erase and program. If I were starting out
from zero, I wouldn't waste my time.
I dunno, man. Flash is often a pain to deal with, mainly due to
the lack of standardization that I mentioned earlier. But to each
his own.
If you don't like flash, there are alternatives.
FRAM, for example,
is of a size that would adapt very nicely to a "vintage" project. I
believe that 5v DIP-based parts are still available. That might also
conveniently bypass the need for an emulator.
I've played with I2C FRAMs, but not byte-wide parts. Are they
easy to program?
Or just get an EEPROM programmer and forget about the
eraser.
Pinouts are reasonably close to UV EPROM in many instances, so if you
wanted to go "authentic", there wouldn't be a problem.
That's true...but then you're squarely in "specialized tools"
territory again.
Please note that I've got a couple of programmers
as well as an
eraser--and a big pile of EPROMs. I use them. But I don't find it
particularly convenient.
Fair enough. :-) I've been dealing with them for a long time (as
you have) and it's just second nature to me; I don't really notice
the inconvenience.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
2:59 a.m.
On 10 Aug 2007 at 2:29, Dave McGuire wrote:
Well I guess I define "obsolete" as
"useless". That seems to jibe
with the industry definition as well.
So, 1701 EPROMs aren't obsolete? ;-) I assume that some can be found
that are still operable.
I've played with I2C FRAMs, but not byte-wide
parts. Are they
easy to program?
Almost exactly like SRAM. You write individual bytes, not the whole
device during a write cycle. Timing for write is about the same as
that for read. The 5V FM1808 (32Kx8) is a 70 nsec part. While not
blazingly fast by modern standards, it's good enough for most
"vintage" designs. Ramtron gives the number of read/write cycles as
being in excess of a trillion. Depending on your decoding logic for
WE\, you could use the same part for RAM and ROM. I've got a couple
here and I like them very much. 28-pin DIP package.
Cheers,
Chuck
3:31 a.m.
Chuck Guzis wrote:
Almost exactly like SRAM. You write individual bytes,
not the whole
device during a write cycle. Timing for write is about the same as
that for read. The 5V FM1808 (32Kx8) is a 70 nsec part. While not
blazingly fast by modern standards, it's good enough for most
"vintage" designs. Ramtron gives the number of read/write cycles as
being in excess of a trillion. Depending on your decoding logic for
WE\, you could use the same part for RAM and ROM. I've got a couple
here and I like them very much. 28-pin DIP package.
I still would like to see the 3.3 Volt part used as a *CORE* memory
replacement since I think it has unlimited R/W cycles.
Cheers,
Chuck
I don't dare think about the logic design since I have no idea of just
how to correctly sequence the power and logic levels reliability.
Ben alias Woodelf
PS. A hefty octal relay and a 115NO45 switches my valve amp nicely but I don't
think this design would work for 3.3Volt switching.
11:24 a.m.
New subject: FRAM as core
woodelf wrote:
Chuck Guzis wrote:
I used a Ramtron FM20L08 128Kx8 3.3 volt part and some 74LVC buffers to
build an S-100 memory card. Works great, just like core. No special
logic of software needed. It's great to be able to turn on the machine
and have it run without booting from an external device. The 3.3v parts
are rated
for unlimited cycles.
Bob
Almost exactly like SRAM. You write individual
bytes, not the whole
device during a write cycle. Timing for write is about the same as
that for read. The 5V FM1808 (32Kx8) is a 70 nsec part. While not
blazingly fast by modern standards, it's good enough for most
"vintage" designs. Ramtron gives the number of read/write cycles as
being in excess of a trillion. Depending on your decoding logic for
WE\, you could use the same part for RAM and ROM. I've got a couple
here and I like them very much. 28-pin DIP package.
I still would like to see the 3.3 Volt part used as a *CORE* memory
replacement since I think it has unlimited R/W cycles.
2:06 p.m.
New subject: FRAM as core
Also check out Freescale's MRAM parts. They have some 16 bit fast (35 ns) ones.
Bob
2:53 p.m.
New subject: FRAM as core
On 10 Aug 2007 at 11:06, Bob Rosenbloom wrote:
Also check out Freescale's MRAM parts. They have
some 16 bit fast (35 ns) ones.
I recall reading about FS's MRAM technology; I hadn't realized that
they were producing them yet. One aspect of MRAM that I might find a
bit worrisome is that it does seem to have a certain sensitivity to
external magnetic fields. I have no idea if this is a real issue.
On the Ramtron parts, I forgot to mention that some families have a
software write-protect feature. So using one as ROM+RAM is very
attractive.
A very clever idea is Ramtron's integration of FRAM with an 8051
core. I can see all sorts of possibilities with embedded
applications being able to pick right up after a power interruption.
Cheers,
Chuck
3:04 p.m.
New subject: FRAM as core
Chuck Guzis wrote:
A very clever idea is Ramtron's integration of
FRAM with an 8051
core. I can see all sorts of possibilities with embedded
applications being able to pick right up after a power interruption.
I think that is more of the case of having a POWER FAIL interupt
than the hardware memory.
Cheers,
Chuck
12:32 p.m.
On Aug 10, 2007, at 2:59 AM, Chuck Guzis wrote:
Pick, pick, pick! ;) I will try to be more clear about what I
mean. "Obsolete" means, to me, "no longer of any practical use".
I'd love to get ahold of a few of those. I'll see if I can tack a
few into my next parts order.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
Well I
guess I define "obsolete" as "useless". That seems to jibe
with the industry definition as well.
So, 1701 EPROMs aren't obsolete? ;-) I assume that some can be found
that are still operable. I've
played with I2C FRAMs, but not byte-wide parts. Are they
easy to program?
Almost exactly like SRAM. You write individual bytes, not the whole
device during a write cycle. Timing for write is about the same as
that for read. The 5V FM1808 (32Kx8) is a 70 nsec part. While not
blazingly fast by modern standards, it's good enough for most
"vintage" designs. Ramtron gives the number of read/write cycles as
being in excess of a trillion. Depending on your decoding logic for
WE\, you could use the same part for RAM and ROM. I've got a couple
here and I like them very much. 28-pin DIP package.
7:03 p.m.
On Aug 10, 2007, at 12:57 PM, Chuck Guzis wrote:
An excellent idea, I will do exactly that.
*click* *click click*
It seems they want to have a salesdroid contact me to send me
samples...I suppose I can stomach that, as long as he doesn't have an
overactive sales gland.
-Dave
--
Dave McGuire
Port Charlotte, FL
Farewell Ophelia, 9/22/1991 - 7/25/2007
I'd
love to get ahold of a few of those. I'll see if I can tack a
few into my next parts order.
Ramtron is still hungry enough to offer samples. Check their web
site.
8:08 p.m.
On 10 Aug 2007 at 19:03, Dave McGuire wrote:
It seems they want to have a salesdroid contact me
to send me
samples...I suppose I can stomach that, as long as he doesn't have an
overactive sales gland.
Ah, how times have changed. Remember when sales droids would take
you out to lunch and get you thoroughly lubricated?
Cheers,
Chuck
11:38 p.m.
It seems
they want to have a salesdroid contact me to send me
samples...I suppose I can stomach that, as long as he doesn't have an
overactive sales gland.
Ah, how times have changed. Remember when sales droids would take
you out to lunch and get you thoroughly lubricated?
1:06 p.m.
On 10 Aug 2007 at 12:32, Dave McGuire wrote:
Pick, pick, pick! ;) I will try to be more clear
about what I
mean. "Obsolete" means, to me, "no longer of any practical use".
I've two wonderful words for this kind of stuff. "Obsolescent" and,
better yet, "quaint". As in "This laptop comes with an internal
floppy drive, a quaint nod to yesteryear."
Cheers,
Chuck
3:14 a.m.
On Fri, 2007-08-10 at 02:29 -0400, Dave McGuire wrote:
I've got a bit pile of various sizes of EPROM, mostly for storing audio
samples in for various bits of (commercial and homebrew) musical
equipment. I don't find running out of blank EPROMs and having to talk
half an hour to erase them a particularly onerous task - it's time to
walk away from the problem and make a cup of tea and a sandwich. It's
too easy to get sucked into the "must get it done" frame of mind, which
is surely akin to the infamous "get-home-itis" that pilots get.
Gordon
Please note
that I've got a couple of programmers as well as an
eraser--and a big pile of EPROMs. I use them. But I don't find it
particularly convenient.
Fair enough. :-) I've been dealing with them for a long time (as
you have) and it's just second nature to me; I don't really notice
the inconvenience.
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