Re: My Vintage Dream PC

No, but it makes one hell of a vaporizer.

if

good

Even on an isolated system there will be exactly one NTP master, which may receive reasonably synchronized time in other (fully unidirectional) ways. Moreover, with group synchronized time that is asserted at each Boot/IPL the synchronization issue almost completely goes away (short of intentionally lying to every computer and preventing any real world input to the contrary). Even then it still effectively goes away for that equipment group.

I=20

Sitting=20

Is it possible to purchase so many as 3 "dead" 35s (or 9100s) from you? =09

But i never liked the smell of the diazo process running.

That is very small project in terms of software. Even my ASIC/FPGA testbenches are sometimes 5x bigger ;)

The problem is how to define these interfaces. Modules have interactions at different levels of hierarchy and trying to keep all those in mind during design phase is difficult. When you approach the millions of lines of code, then the documentation also is in the range of (ten)thousands of pages. Trying to keep that kind of monster in control is not easy.

Unit level interaction problems are quite common, they are usually caused by misunderstandings of the big picture. Of course also unit level problems are common, they could be mitigated via module testing etc. but that costs money. The development process is always compromise between time to market, price and reliability. Maybe in military projects the time and money are not a problem ;)

--Kim

Not to diminish good fresh bread, but i also like good steak, good fish, good poultry, and similar hot off the grill. Also fresh string beans, broccoli, cauliflower, interesting salads, and fresh fruit.

Mmmmm... steak.

I also like belly meat blue fin tuna sushi, but there is not much in the way of aroma coming off it. Sure tastes amazing though.

thesis=20

time,=20

in=20

so it=20

I have worked with plenty of machines with no ROM whatsoever. You had punch in by hand the most trivial tools, then use that to add a loader, maybe 50 words or so (of 150 to 200 bytes on a byte oriented machine). Then, on the machines i used, a paper tape could load any useful program. Once you had some ROM to work with booting/IPL got much easier.

Hence "There's always time to do it over and never time to do it right".

-- Steve O'Hara-Smith | Directable Mirror Arrays C:>WIN | A better way to focus the sun The computer obeys and wins. | licences available see You lose and Bill collects. |

The big difference between cars and programs is that programs are generally one off designs done under time pressure with urgent spec changes at the last minute. There are usually glaring errors in every stage from requirements to final product - some of the errors cancel each other out, many are never found.

That being said - my BSD boxes run reliably for as long as I care to run them, start reliably whenever I choose to start them, opening vi never causes sylpheed to fail (to pick two applications at random). Most unixish systems will run crashme indefinitely (crashme is a delightful program that populates a chunk of memory with random numbers and then executes it after setting handlers for all the error signals this behaviour is likely to produce) without causing problems to anything on the system.

In other words there is reliable software and it has become reliable through pretty much the same process that cars and jet planes have become reliable - refinement in light of experience. Cars were far less reliable in 1920 or even 1950 - it wasn't until well into the 1970s that electric start was reliable enough to dispense with the cranking handle completely. They have become reliable because over the years engineers have been learning about, understanding and removing the causes of unreliability.

There's always a question of how much "scaffolding" you want to take the time to write. If you have one module in isolation you have to write code to provide its inputs and do something with its outputs. When you do that, you still have a potential problem with misinterpretations and bugs, so you're not much further ahead than if you tested large chunks of code all together.

I can't exactly recall that PDP-11 video on U-Tube. Didn't they have to toggle in the initial bootstrap in order to load the paper tapes?

The university I went to had a grad level course which consisted of writing a compiler. There were no classes.

/BAH

Nor complicated like a monitor can be.

/BAH

I once had a secretary who would condemn anybody who drank beer but would figure out how to spend an hour making ditto copies.

/BAH

Most CS departments have an undergrad class in compiler writing, in which the term project is to write (for a toy language, of course). They don't write it in machine code!

I suspect getting time on one of those 5 computers would be like getting observation time on the hubble.

I should ask around the MV plant and see if there's anyone left that remembers.

scott

Nah - it's gotta be hand-kneaded. The little droplets of sweat add to the flavor! ;-)

Cheers! Rich

I don't think I could bear to part with any of them. Well, maybe a dead '35. I want to fix the 9100s some day. Unfortunately, HP never released the schematics for some bizarre reason. The HP historian has a trove of documentation on the 9100 that they won't release, so 9100s are going into dumpsters.

John