IBM ROM BASIC or lack thereof

From: Carlini, Antonio <Antonio.Carlini_at_riverstonenet.com>
Date: Tue Oct 9 17:00:29 2001

        ard_at_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
Received on Tue Oct 09 2001 - 17:00:29 BST