On Mon, Feb 11, 2019 at 4:13 PM Jon Elson via cctalk <cctalk@classiccmp.org> wrote: > > On 02/11/2019 07:04 AM, Noel Chiappa via cctalk wrote: > > A look at the RK11 registers after the swap-out showed an anomaly; something > > about the extended memory address bits? (Maybe a multi-block transfer than > > crosses a 64KB boundary? That would explain the address sensitivity we were > > seeing.) Hopefully he'll track it to its lair shortly. > > > > > OH, BOY! I think you may have found it. Likely some disk > controllers did NOT SUPPORT crossing 64K boundaries! The > diags would not detect that, as it was likely expected > behavior. I would suspect the driver would need to break up > these operations.
I _think_ the RK11-C should cross a 64K boundary correctly. There's an output from the low 16 bits bus address module (M795) on pin BP2 'D15 RKBA=ALL 1 L' (page 27 of the schematic on Bitsavers) that goes to the counter that holds the 2 extended bits, pin C1 of the M239 in slot A17 (page 13 of the same .pdf) [I am working from 'RK11-C_schemFeb1971.pdf' from bitsavers] Of course if there is a fault in this area then it will not correctly increment the top 2 bits, but that might give you somewhere to check. -tony
