IBM ROM BASIC or lack thereof - test-drb@ccmp.vtda.org

9 Oct 2001

	ard(a)p850ug1.demon.co.uk wrote:

...
 But seriously, the advantage of paper manuals is that
you can read them 
...
 anywhere (like in bed, on the train, etc) , you can
have them open on 
...
 your workbench (where there certainly isn't room
for a PC in my case), 
...
 you can write notes all over them, etc. And I find them
a lot easier to 
...
 read... 
	All very true and I completely agree. I too
	generally prefer paper manuals. I would
	also hate to read a manual on-screen 
	cover to cover (i.e. for anything other than
	reference). However, my space is restricted.
	I could have maybe 300 manuals within easy 
	reach here. I have a wall-mounted CD rack
	with space for 300 CDs just feet away.

...
 > 
> I don't expect to read my manual on the Rainbow that I
> am repairing ... that's what the PC or laptop 
...
 Need any hints? I've got a fair idea as to what
goes on inside the 'bow 
...
 (pinouts, theory, etc). Some of it is not obvious (like
the disk 
controller test which feeds the output of the serial chip in sync mode to 
...
 the read data pin of the FDC to check that the latter
can decode data 
...
 correctly). 
	I have the tech manuals but this is the
	PSU (second one which I've had die on me!)
	The first one turned out to be the bridge
	rectifier ... I found a suitable replacement
	and bingo it came back to life. Only a few
	weeks later I found somewhere that sold
	security bits online, one of which fits
	the Rainbow PSU - so at least this time
	I won't be sawing a slow in the screw to
	get at the thing! This time whatever
	died has taken out more of the downstream
	stuff. I've not had too much time to look
	at it - you don't happen to have the PSU
	schematics do you? ... I've got
	everything else (I think) except that.

...
 I've never quite understood this... 20-30 years
ago, most computers used 
...
 standard chips. And thus they could be copied (I am not
talking about 
...
 legality here). But the schematics existed. Manuals
explaining the 
schematics existed. 
	In DEC, I was told that they stopped supplying
	them when they noticed that customers did not
	want them any more (and obviously these things -
	especially technical manuals) cost mucho
	denaro to produce ... schematics must already
	exist obviously! This was when the customer
	base moved from being propeller-heads to
	suits.

...
 Now we have ASICs which are much harder to copy, and
yet the docs don't 
...
 exist...

Anyway, any half-decent hacker can reverse-engineer most devices in a 
...
 couple of days at most.... 
	The board for which I am currently scribbling
	software has a few standard, identifiable chips
	on it but the interconnections are mostly 
	mediated by a few large FPGAs. There are
	also some custom ASICs in there too. 
	The memory map is entirely decided
	by the FPGA. Adding and removing
	caps resistors and other SMT components
	is not too bad but playing with one of the 
	750-plus pin BGA devices is probably
	beyond the realm of the hobbyist (although
	re-work houses do exist, so who knows?)

...
 > my current TV came with a five year guarantee and
the
> previous one was a Decca series 80 chassis that was already 
...
 I probably have that schematic somewhere... I've
got a lot of volumes of 
...
 Poole+Molloy (and its successors) on the shelf. 
	For the record, it's a Philips 21PT5322 and the
	other one is a Fergusson T14R. (The latter
	is now out of guarantee and is therfore 
	"fair game" ... ).

Antonio