On 2019-06-26 19:54, Bob Supnik wrote:
Implementing a more complete form of read/write/write check header is
not as straightforward as I thought, because the RP and RM drives use
different header formats.
The RP expects 4 16 bit words, of which the first two are used, and the
second are "for software". Word 0 is cylinder plus 18b/16b, word 1 is
sector, words 2 and 3 are "keywords".
The RM expects 2 16 bit words, both used. Word 0 is cylinder plus
18b/16b plus two bad block indicators. Word is 1 is track and sector.
The simulator supports the RP06, RP07, RM02/3, RM05, and RM80. I'm not
sure if the RP07, RM05, or RM80 were ever actually qualified for the
KS10. However, the RP06 and RM02 both shipped with the system, so the 2
word/4 word distinction would have to be implemented.
I can't find the sector format for the RP07 which, despite its name,
behaved like an RM series drive.
The RP07 is actually even more complicated. I wrote a formatter for RSX
for it at one point. It was more of a hack than really properly doing
the formatting. As far as I remember, for the RP07, you can even specify
the gap between sectors, which potentially allows you to map around bad
spots on the disk. So there is information about that kind of things in
the header as well.
I can't remember where I got the RP07 information from back then, but
probably the set of microfiches we had.
I would vote for someone doing just the naive write as a starting point.
I think much software will be happy enough with just that, and then we
can look at specific when we locate software that really do care about
what is written into the headers.
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: b...@softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
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