[Simh] 8" Floppy disk image getting HALT error

[Johnny Billquist]

Hi, Ragge, :-)

On 2017-07-11 23:50, Anders Magnusson wrote:
> Den 2017-07-11 kl. 14:29, skrev Johnny Billquist:
>>
>> To sum things up. You can probably ignore all the questions about if
>> this really is some DEC floppy, what kind of format it has, and so on.
>> If kryoflux managed to extract data that looks valid with RX02
>> parameter settings, then I'd say we can be sure it is an RX02 disk.
>> And this format was unique to DEC, so it can't be anything else.
>>
> Nitpicking:  Sintran had the same format (F-F 12 IIRC) so DEC floppies
> could be used by Sintran and vice versa.
> The RX02 floppies were pre-formatted by DEC and were quite expensive,
> but any floppy could be formatted using Sintran and then used on a VAX
> for example :-)

Are you confusing the RX01/RX02 with the RX50 now?
The RX01 is a bog standard IBM format SSSD floppy.
The RX02 is the same as an RX01. DEC just flips a bit in the header of 
each sector, and write the data in double density. So you can always 
easily format back and forth between RX01 and RX02 in the floppies, and 
anyone could do it.

The RX50 on the other hand was preformatted, and in a format that (I 
thought) noone else used. So DEC really had a captive market for that one.

I've used plenty of IBM 8" floppies in RX01 drives... Never had an RX02 
myself, so I could not do the reformatting for that. But look inside any 
DEC OS, and you'll find the command to reformat RX01 as RX02 and back.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol