Hazards of link boot

Hazards of link boot

Post by Randy Brumbau » Thu, 18 Jan 1990 03:56:54



Recently we have run across a problem with transputers in
distributed systems.  I am hoping somebody has an elegant
solution that they will share.

The problem concerns the hazards of booting from link in a
distributed system.  If a transputer system is running
along, chatting on several links and is reset, either by a
watchdog or power glitch, what happens?  If it is set to
boot from link, the first data to arrive will be interpreted
as bootstrap.  The data received may or may not be a valid
program load (probably not), but the results are certainly
unpredictable.

I can think of several solutions, none of them very good:

1- Don't boot from link.  The idea of a small primary bootstrap
 in PROM seems like a good one, unless board space is tight.
 Only a few bytes are needed, but the PROM must be 32 bits wide,
 so at least a 40 pin package would be needed. (And I don't know
 of any 32 by few byte PROMs).

1a- I have heard of PROMs with serial outputs.  If one of these
 could be used, it might help.  The design that comes to mind
 is a serial PROM to a shift register to a C0011 to a link, which
 is messy and probably take as much space as 32 bit PROM design.
 It also would tie up one link.

2-  Dedicate a transputer as master, which monitors other
 transputers, via a heartbeat or discrete.  The link from the
 master to the "slaves" would only be used for booting.  This
 also ties up a link and limits topology choice.

3-  "We all go down together" - any processor reset resets every
 processor, and the prcedure is the same as initial system start.
 This seems easy, but stupid - any processor unit that is having
 problems can disable the whole system.  

None of these seems very good.  I would like to hear from anybody
with a better scheme, or who has tried these and has any advice.

Randy Brumbaugh

(805) 258-2177

 
 
 

1. Boots, boots, boots, boots...

As comp.sys.carboot doesn't exist yet, I thought I'd post
here.  Also, see my reply to "This made me smile....".

I was recently (Sunday December 5th) at a car boot sale in
Strood, Kent.  (What, again?  --  Ed)


or whatever), or a CPC464 for the same.  The same stall also
had an unmarked keyboard with a cartridge slot (MSX?  TI
99/4a?), and a computer marked "Atari" which I couldn't
recognise.  (It wasn't a 2600 or XL, and I don't think it
was an ST.  It had four large pastel coloured buttons on it
IIRC.)

I could also have got a CD-RW drive for only [=A3]99
(rats!), although the same stall was also selling a pack of
ten CD-Rs for just over a quid *more* that the ones I bought
recently (which were better quality anyway).

--
--------------------------------------------------
Regards, Robert the Eboreg
New?  Read the FAQ:  http://www.kendalls.demon.co.uk/cssfaq/
Got a binary file to post?  Go to alt.binaries.comp.sinclair
Want to e-mail me?  Drop dead!

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