Hi Peter The TM section (4.11) on the read-write register looks to me like a comprehensive descrioption of it's functionality; esp if read with an LS299 data sheet. There may be second order points which study of the maintenance (schematic) prints will reveal - but I would be surprised, this is intened to be vanilla.
The (useful) student guide you identified gives a good precis of R/W register function on page BD-15ff. The R/W register looks like a 16 bit register, writable at byte granularity for testing / exercising minimal systems. Very useful for low level diagnostics / faultfinding of DATI DATO DATOB bus cycles. HtH; Martin -----Original Message----- From: Peter Ekstrom via cctalk <[email protected]> Sent: 23 November 2025 16:52 To: General Discussion: On-Topic and Off-Topic Posts <[email protected]> Cc: Peter Ekstrom <[email protected]> Subject: [cctalk] Re: BDV11 programming information Hi Glen, Yes, and I have looked over it several times. It does have quite a bit of info, but it doesn't go into much detail for the R/W register. I also found a student guide that includes the BDV11 and it help shed some light on how the code in the ROMs is segmented. It helped me visualize more how it is done. But I am still missing things like the details for the R/W register. https://wwcm.synology.me/pdf/EY-DX056-SP-002&J6269-A&EY-DX052-SG-002%20Small%20Systems%20Training%20PDP-11V23-&%2011T23%20System%20Maintenance%20Student%20Guide.pdf - Peter On Sun, Nov 23, 2025 at 10:52 AM Glen Slick via cctalk < [email protected]> wrote: > On Sun, Nov 23, 2025, 6:32 AM Peter Ekstrom via cctalk < > [email protected]> wrote: > > > Does anyone know if there is any programming information about the > > BDV11 card? > > I have disassembled the ROM files for it and I see they do various > > operations with the registers on the card, but it is not clear to me > > exactly what they are doing. > > > > - Peter > > > > Did you already find this? > > http://www.bitsavers.org/pdf/dec/qbus/EK-BDV11-TM-001_Mar78.pdf > > > >
