30 Jul
2004
30 Jul
'04
12:57 p.m.
From: vrs <vrs(a)msn.com>
Hi
I did some searching on the web but never found any
27c256's faster than 70ns. I did find 27c512's and 27c010's
at 45ns a couple of places.
Dwight
OK. I was thinking about the microcode ROMs in an
HP9810 (somethign that
_I_ am working on, and those are most certainly 'hit' as soon as INIT is
deaseserted and the microocde program counter starts to change. I prefer
to think of general-purpose solutions (i.e. somethign that will replace
every 256*4 ROM), rather than soemthing that works only in specific
machines under specific circumstances.
I must not be getting it, somehow.
Why can't you just use a 45ns or 55ns 27c256 or 27c512 and swizzle the
pinout? These are around $3 per chip, and seem to meet the requirements.
Vince
30 Jul
30 Jul
1:21 p.m.
I must not be
getting it, somehow.
Why can't you just use a 45ns or 55ns 27c256 or 27c512 and swizzle the
pinout? These are around $3 per chip, and seem to meet the requirements.
Vince
Hi
I did some searching on the web but never found any
27c256's faster than 70ns. I did find 27c512's and 27c010's
at 45ns a couple of places.
Dwight 
31 Jul
31 Jul
2:06 a.m.
At 06:21 PM 7/30/04 -0700, you wrote:
(Looks again.) I found 27c256 and 27512 at 45ns at Digikey, and 45ns 27c512
at JameCo. Mouser also has the 45ns 27c256, but only has 55ns 27c512. (Are
you in the states?)
So, do these meet the requirements? (Seems like you could even burn several
different images into the chips and use a DIP switch to select which image
using the high address lines :-).)
Also needn't worry about holding reset, or batteries going dead, or a big,
complicated daughter board?
(I don't know the specs for the bipolar ROMs being replaced. Someone
earlier said they were 50-60ns. I am assuming they were also fairly small
(logically, if not physically) compared to a 27c256.)
The ones in the HP 1000 are 4 x 256 and are sixteen or eighteen (I
forget which) pin .3" wide DIPs. Al has pins out for some of the different
BiPolar PROMs on his site. I think they're under the games machines
section. There's no room for a duaghterboard to mount on the HP 1000 card.
You'd have to mount it elsewhere and cable over to it.
Joe
I must not be getting it, somehow.
Why can't you just use a 45ns or 55ns 27c256 or 27c512 and swizzle the
pinout? These are around $3 per chip, and seem to meet the requirements.
Vince
Hi
I did some searching on the web but never found any
27c256's faster than 70ns. I did find 27c512's and 27c010's
at 45ns a couple of places.
Dwight
Vince
6:17 a.m.
From: "Joe R." <rigdonj(a)cfl.rr.com>
OK, that helps a lot to get me on the same page.
Can you use the 74S571? Those appear to still be available from JameCo
(part #48910) at 35ns address-to-data, 25ns enable-to-data. They are 512x4
16 pin DIPs. $5.69 qty 1, $5.49 qty 10. Haven't found them elsewhere,
though.
Not knowing what I am looking for, I wasn't able to find the pinouts on Al's
site, however. Can you provide a pointer or at least a part number?
For one thing the parts used in the HP 1000 are 25
to 35 nS parts. Also
the enable and other control lines are very different so you'd need a fair
amount of glue chips and probably a buffer.
>(I don't know the specs for the bipolar ROMs
being replaced. Someone
>earlier said they were 50-60ns. I am assuming they were also fairly
small
(logically, if
not physically) compared to a 27c256.)
The ones in the HP 1000 are 4 x 256 and are sixteen or eighteen (I
forget which) pin .3" wide DIPs. Al has pins out for some of the different
BiPolar PROMs on his site. I think they're under the games machines
section. There's no room for a duaghterboard to mount on
the HP 1000 card.
You'd have to mount it elsewhere and cable over to it.
Wouldn't that cost you a few nanoseconds just in the cabling? ISTR cable
delays measured in ns/ft.
Thanks!
Vince
6:55 a.m.
There's no
room for a duaghterboard to mount on the HP 1000 card.
You'd have to mount it elsewhere and cable over to it.
Wouldn't that cost
you a few nanoseconds just in the cabling? ISTR
cable delays measured in ns/ft.
2:55 p.m.
At 11:17 AM 7/31/04 -0700, you wrote:
From: "Joe R." <rigdonj(a)cfl.rr.com>
OK, that helps a lot to get me on the same page.
Can you use the 74S571? Those appear to still be available from JameCo
(part #48910) at 35ns address-to-data, 25ns enable-to-data. They are 512x4
16 pin DIPs. $5.69 qty 1, $5.49 qty 10. Haven't found them elsewhere,
though.
Bob Shannon has ordered these and gotten them so I'm wondering why all
the sudden interest in using EPROMs or SRAMs. But I thought I'd let the
discussion continue and see what developes. From what Bob told me he
orders one specific part but Jameco sends him several different brands.
They're supposed to be equivilent but apparently that's only in read mode.
They are programmed differently and he's had both good and bad luck
programming them.
Joe
For one thing the parts used in the HP 1000 are
25 to 35 nS parts. Also
the enable and other control lines are very different so you'd need a fair
amount of glue chips and probably a buffer.
>(I don't know the specs for the bipolar
ROMs being replaced. Someone
>earlier said they were 50-60ns. I am assuming they were also fairly
small
(logically, if not physically) compared to a 27c256.)
The ones in the HP 1000 are 4 x 256 and are sixteen or eighteen (I
forget which) pin .3" wide DIPs. Al has pins out for some of the different
BiPolar PROMs on his site. I think they're under the games machines
section.
Not knowing what I am looking for, I wasn't able to find the pinouts on Al's
site, however. Can you provide a pointer or at least a part number?
There's no room for a duaghterboard to mount
on the HP 1000 card.
You'd have to mount it elsewhere and cable over to it.
Wouldn't that cost you a few nanoseconds just in the cabling? ISTR cable
delays measured in ns/ft.
Thanks!
Vince
3:35 p.m.
Joe wrote...
Bob Shannon has ordered these and gotten them so
I'm wondering why all
the sudden interest in using EPROMs or SRAMs. But I thought I'd let the
discussion continue and see what developes. From what Bob told me he
orders one specific part but Jameco sends him several different brands.
They're supposed to be equivilent but apparently that's only in read mode.
They are programmed differently and he's had both good and bad luck
programming them.
It was Bob that told me he had pretty pitiful luck with finding
ones, and
the ones he did find had a very low success rate. Hence, the discussion of
EPROMS and SRAMS.
>> There's no room for a duaghterboard to
mount on the HP 1000 card.
I beg to differ. But one could always run a short and
heavily shielded cable
to it.
Jay
9:11 p.m.
In message <006c01c47778$a180f320$6400a8c0@HPLAPTOP>
"Jay West" <jwest(a)classiccmp.org> wrote:
It was Bob that told me he had pretty pitiful luck
with finding ones, and
the ones he did find had a very low success rate. Hence, the discussion of
EPROMS and SRAMS.
What about using a GAL programmable logic chip?
Use CUPL's "lookup table" feature, use the 8 (or was it 9?) inputs on a
GAL16V8 as address inputs and use the outputs as data outputs. IIRC the
propagation delay for a normal GAL is 15nS, but you can get them in speeds
down to 7nS.
Pricing in 10-off for GAL16V8D-QP chips was somewhere around ?1 ($2) each
last time I ordered some.
As far as programming goes, there are designs for a programmer called the
"GALBlast" floating around the 'Net. Make sure you get the latest version
(1.6 IIRC) from the author's homepage. I found a single-sided PCB layout
that used an R2R ladder on a site called "mpu51". I subbed a BFY51 for the
power switching transistor and a BC557 (jellybean PNP) for the PNP
transistor. It seems to work fine, but the 7805 NEEDS a heatsink, unless you
feel like trying to work out why the programmer won't work. I used a piece of
scrap aluminium sheet, bent into a flattened "U" shape.
The source code is included with the programming software, so you could
probably write your own driver to run it. IIRC the guy who designed the
GALBlast was Manfred Winterhoff (aka MaWin).
My GALBlast works, but YMMV.
Later.
--
Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB,
philpem(a)dsl.pipex.com | ViewFinder, 10BaseT Ethernet, 2-slice,
http://www.philpem.dsl.pipex.com/ | 48xCD, ARCINv6c IDE, SCSI
... If this were an actual tagline, it would be funny.
1 Aug
1 Aug
2:42 a.m.
From: "Philip Pemberton" <philpem(a)dsl.pipex.com>
What about using a GAL programmable logic chip?
Use CUPL's "lookup table" feature, use the 8 (or was it 9?) inputs on a
GAL16V8 as address inputs and use the outputs as data outputs. IIRC the
propagation delay for a normal GAL is 15nS, but you can get them in speeds
down to 7nS.
Isn't there a shortage of product terms? I thought there were only 8
product terms per output. Unless the data in the PROMs being replaced is
fairly regular, that doesn't seem enough to guarantee success.
Vince
2:49 a.m.
At 10:35 PM 7/31/04 -0500, you wrote:
Joe wrote...
I think the reason that Bob has had such little success is due to the
fact that his programmer only has one setting for the 256 x 4 PROMs and it
tries to program all of them the same way. If you look at the settings used
in in a Data I/O 29, Stag or Prolog programmer you'll see that the
different brand parts are programmed with different settings. I think
you'd have MUCH better success programming the parts with those
programmers. I have a pamplet from Pro-Log that describes PROMs and EPROMs
and it list the different types of technology and materials used in the
PROMs. They are VERY different from each other. EPROMs are pretty standard
but PROMs aren't.
Hence, the discussion of
Bob Shannon has ordered these and gotten them
so I'm wondering why all
the sudden interest in using EPROMs or SRAMs. But I thought I'd let the
discussion continue and see what developes. From what Bob told me he
orders one specific part but Jameco sends him several different brands.
They're supposed to be equivilent but apparently that's only in read mode.
They are programmed differently and he's had both good and bad luck
programming them.
It was Bob that told me he had pretty pitiful luck with finding
ones, and
the ones he did find had a very low success rate. EPROMS and SRAMS.
> >> There's no room for a duaghterboard to mount on the HP 1000 card.
I beg to differ.
??? On my 1000s the board with the PROMs is located in the bottom of the
chassis and UNDER an aluminium plate with just enough room for the parts on
the board to clear the plate. In fact, there are holes in the plate to
allow access to the PROMs without having to remove the board from the
bottom of the machine. The holes aren't very big, perhaps 1 1/2 x 2 inches
so I doubt you could build a dautherboard small enough to fit inside of one.
Joe
But one could always run a short and heavily shielded cable
to it.
Jay
7212
days inactive
7214
days old
9 comments
6 participants
participants (6)
-
dwight.elvey＠amd.com -
jwest＠classiccmp.org -
mouse＠Rodents.Montreal.QC.CA -
philpem＠dsl.pipex.com -
rigdonj＠cfl.rr.com -
vrs＠msn.com