Forums

How to choose a firmware partner

Started by robi...@tesco.net May 26, 2004
Paul Keinanen <keinanen@sci.fi> says...

>While computer systems with 1 MB of memory could have been done in >1975/76 using 4 kbit x 1 (requiring 2000-2500 DRAMs), but I doubt that >making 1 MB with 1kbit x 1 SRAMs (requiring 8000-10000 chips) would >have been very practical due to the high power consumption.
See my post titled "Two Megabytes of Core Memory in 1965" for an example of a 1978 computer with 4MB of semiconductor RAM. -- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/
"Steve at fivetrees" <steve@NOSPAMTAfivetrees.com> wrote in message news:<O6ednZVgQbk_4ind4p2dnA@nildram.net>...
> <robin.pain@tesco.net> wrote in message > news:bd24a397.0405260202.5241051c@posting.google.com... > > How to choose a firmware partner: > > > > Ask if it's policy to enable the watchdog timer. The correct answer is > > "no". > > Utter twaddle.
How do you know if you have the optimum distribution of clear-WDT instructions? If your system is simple enough to predict this, then it is simple enough to code without the risk of depending on state to avoid lockup. If your system is too complicated to predict optimum distribution then you must err on the safe side allowing bugs to remain undetected because they are masked by watchdog resets.
> > > If they say "yes" then you know that their code is dodgy, and/or their > > hardware is vulnerable and if the WDT is not going off occassionally, > > it probably will after the next modification. > > Watchdogs are not there to protect against dodgy code and/or unduly > "vulnerable" hardware. They're there because, ultimately, *all* hardware is > vulnerable. It's just a question of degree. If you don't believe me, equip > yourself with a Schaffner and try dumping a fast-rise time 2kV spike into > nearby metalwork...
Yes we do this, without problems. Our code is inherently safe. This is easy to do because it is small.
> > Robin, I'm afraid your ignorance is showing.
I was afraid someone would say that. Robin
robin.pain@tesco.net wrote:
> Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote in message news:<v1c9b01lvf8cgr8v0tpnrqq68scujkalih@4ax.com>... >>Yes, the TROLL-O-METER needle is flickering upscale a bit. >> >>Best regards, >>Spehro Pefhany > > So this may seem (a troll), to some people, but won't anyone even > consider this for a moment: > > 1) A one byte loop is lockup-proof.
Yes, I did consider that for a moment, but then the Troll-o-meter kicked in, as it did on the first post. -jg
"42Bastian Schick" <bastian42@yahoo.com> wrote in message
news:40b58017.150644144@news.individual.de...
> On 26 May 2004 15:35:23 GMT, cbarn24050@aol.com (CBarn24050) wrote: > > > >The watchdog timer is a fairly recent invention, millions of older
systems run
> >fine without them. > > Fine. That is why I have to power-cycle my settop box from time to > time. If they only had build in a WDT, I would not have to climb > behind my TV (of course the settop box has no switch, also a new > _invention_).
Absolutely - I (or rather my daughter) is adept at this. Set-top boxes seem to be particularly bad, and I believe I know why... Steve http://www.sfdesign.co.uk http://www.fivetrees.com
<robin.pain@tesco.net> wrote in message
news:bd24a397.0405270005.70b8698c@posting.google.com...
> 1) A one byte loop is lockup-proof.
Untrue.
> I am guessing that the above posters are talking of complicated, > multiproccessor, asynchronous systems; which is a little narrow > minded.
I've used watchdogs (external hardware watchdogs, i.e. cannot be disabled) in systems with a single 8-bit CPU, 128 bytes of RAM, and under 2k of ROM. Again, you're missing the main point of using a watchdog. It's nothing to do with software. Steve http://www.sfdesign.co.uk http://www.fivetrees.com
>>In the very late '60s I worked on a UNIVAC 1110 which had that >>much memory but I can't say now if it was core or semi. > >Are you sure it wasn't an 1108 or 1106? The 1110 was introduced on >November 10, 1970. (Many web pages say 1972, but they are wrong.) > >The 1110 had a full megaword of memory, which is over four >megabytes (36 bit words). It also had plated wire memory in >addition to the core. In 1976 the 1110/40 came out, which was >an 1110 with a megaword of (faster) RAM chips instead of core. >
Forgive my ignorance (I was released 1970), what is the difference between core and RAM chips ? --- 42Bastian Do not email to bastian42@yahoo.com, it's a spam-only account :-) Use <same-name>@epost.de instead !
In article <BZctc.6663$lY2.2247@fe1.texas.rr.com>,
"Anthony Fremont" <spam@anywhere.com> wrote:
> >"Phil" <please@sendmejunkmail.com> wrote >> >> "Anthony Fremont" <spam@anywhere.com> wrote > >> > A full megabyte....in the 60's?....that's pretty big. I programmed >on >> > WWMCCS GE/Honeywell mainframes in the early 80's that didn't have a >full >> > megabyte of magnetic core memory. >> > >> >> I would be interested (and surprised) to know which >> computer had a megabyte of core in the 60's. >> see http://www.crowl.org/Lawrence/history/computer_list >> to help "refresh your memory" (bad pun). >> I worked on Elliot 920B's (not on the list) perhaps >> because it was military?? > >I would like to know as well. I worked on Honeywell 6000's and when I >say early 80's, I mean July of 1980 and on. IIRC (and I think I do ;-) >they had about 128K words of core, and each word was 36 bits. They
Talking '60s the GE-635 ancestor to the H6000 had physical address space for 256KWords -- about a megabyte. It doesn't look like more could be added, but it's not entirely clear from the docs I have. The first Canadian 635 installation was '64-'65ish. H6000 physical address space could have been as much as 6 "megabytes". The system I worked on was installed with 512KWords. Enlarging to 768KWords exposed a bug in the memory allocation software, so I doubt that they commonly got that big, although physically it ran fine. Regards. Mel.
In article <bd24a397.0405270005.70b8698c@posting.google.com>, 
"robin.pain@tesco.net" <robin.pain@tesco.net> writes
>So this may seem (a troll), to some people, but won't anyone even >consider this for a moment: > >1) A one byte loop is lockup-proof. > >2) So for a standalone, MCU, lockup proof code is only a matter of >scale. >
So you've never run code on a standalone MCU in an electrically noisy environment then? -- Tim Mitchell
"Steve at fivetrees" <steve@NOSPAMTAfivetrees.com> writes:

> "42Bastian Schick" <bastian42@yahoo.com> wrote in message > news:40b58017.150644144@news.individual.de... > > Fine. That is why I have to power-cycle my settop box from time to > > time. If they only had build in a WDT, I would not have to climb > > behind my TV (of course the settop box has no switch, also a new > > _invention_). > > Absolutely - I (or rather my daughter) is adept at this. Set-top boxes seem > to be particularly bad, and I believe I know why...
Do tell. (I can crash my set top box in about 10 seconds without even trying. Luckily it has a power switch on the front). Robert --
"42Bastian Schick" <bastian42@yahoo.com> wrote in message

> Forgive my ignorance (I was released 1970), what is the difference > between core and RAM chips ?
Wow, do I feel old now. Magnetic core was a bunch of tiny little "donuts" that looked something like miniscule ferrite beads. It was literally sewn together by meticulous women (peering thru microscopes) into an X, Y type lattice that also had a sense/inhibit wire running throughout all the "donuts". Each little donut could be magnetized into one of two polarities to represent a 1 or 0. When core was read, it destroyed the data stored and had to be automatically rewritten by the hardware. Some guy named Wang figured all this out.