Re: What is the most used ROM in the brown 1541?

Hello Spiro,

Friday, June 19, 2015, 4:58:14 AM, you wrote:

> Hello Julian,

> * On Thu, Jun 18, 2015 at 06:28:39PM +1000 Julian Perry wrote:
>> I think 901229-05 came out pretty early in the peace: The ROM bootstrap
>> "feature" present on 901229-03 was very annoying (I know, I had one) and would
>> have been good motivation to get rid of it.

> Why was it annoying? In fact, I *never* had a problem with that autoboot
> feature. I have read about problems, but never noticed any on my own.

Incompatibility at power up when other devices were present on the IEC
buss. Where it gave me most grief was when my Xetec IEC>centronics
interface was unpowered, the 1541 would often report a ?record not
present error with the drive LED flashing on powerup or reset.
If there was no disk on the drive, it would sometimes also "knock".
Since my drive had trouble holding an alignment at the best of times,
that used to piss me right royally.
Once I learned there was a later ROM that didn't do this I
salvaged one from a damaged 1541 from a friend (elevator engineers
shouldn't try to fix disk drives!!) and the problem (naturally) vanished.
From memory code up to -03 looked for a handshaking line held low at
POST (?CLK?), and if so fired off the disk bootstrap routine.


In case you're wondering why the printer interface was often
unpowered:
Due to incompatibilities with the serial interface and some
turbo-loaders I had a switch installed on my C64 that could cut the 5v
power from the cassette interface.

Julian


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