Great! thank you Glen and also Michael T. for the identifications. So this appears to be a PDP-11/23 with this FC-202 floppy controller. 1. I have read that the card and the drives were compatible with the dec rx02 drives. Why would the CRDS even bother to redesign a card where DEC had perfectly good working ones? Anyone know if there is any value in keeping the FC-202 or just keep with the DEC cards? 2. Any idea on that other card? https://w2hx.com/?prefix=x/What-Is-It/PDP-11-Thing/Board1/ Thanks guys! 73 Eugene W2HX My Youtube Channel: https://www.youtube.com/@w2hx/videos -----Original Message----- From: Glen Slick via cctalk <cctalk(a)classiccmp.org> Sent: Wednesday, April 10, 2024 7:44 PM To: General Discussion: On-Topic and Off-Topic Posts <cctalk(a)classiccmp.org> Cc: Glen Slick <glen.slick(a)gmail.com> Subject: [cctalk] Re: PDP-11 thingy. What is it? On Wed, Apr 10, 2024, 4:14 PM W2HX via cctalk <cctalk(a)classiccmp.org> wrote: H9270 Backplane, Page 366 (page 376 of the pdf) http://www.bitsavers.org/pdf/dec/qbus/EB-23144-18_QbusIntrfs_1983.pdf

rx02 drives. Why would the CRDS even bother to redesign a card where DEC had perfectly good working ones? Anyone know if there is any value in keeping the FC-202 or just keep with the DEC cards? A lot of the third-party controllers could talk to Shugart-style 8" floppy drives. They can also usually *format* the diskettes, which the RX01/RX02 systems from DEC can't do -- you have to use preformatted media. This isn't a *huge* deal since RX01 is just IBM 3740 and you can format it on CP/M boxes, with ImageDisk, etc. There's an XXDP utility to upconvert RX01 media to RX02, which is M2FM and very few things can work with it. Apparently a lot of small shops kept a CP/M box just for the task, the Alspa ACI-2 I had was supposedly used like that. https://w2hx.com/?prefix=x/What-Is-It/PDP-11-Thing/Board1/ Looks like a non-DEC Qniverter -- QBus to Unibus converter. If that's what it is, you'd plug your Unibus cable into that pair of connectors on top and run it to whatever Unibus device you were wanting to talk to, potentially another backplane full of Unibus stuff. Commonish upgrade on e.g. CNC machines that were originally controlled by a PDP-11/05 or something in one Unibus chassis, with another Unibus chassis full of machine-specific cards. Thanks, Jonathan

Jonathan Chapman via cctalk wrote: dec rx02 drives. Why would the CRDS even bother to redesign a card where DEC had perfectly good working ones? Anyone know if there is any value in keeping the FC-202 or just keep with the DEC cards? floppy drives. They can also usually *format* the diskettes, which the RX01/RX02 systems from DEC can't do -- you have to use preformatted media. This isn't a *huge* deal since RX01 is just IBM 3740 and you can format it on CP/M boxes, with ImageDisk, etc. There's an XXDP utility to upconvert RX01 media to RX02, which is M2FM and very few things can work with it. Alspa ACI-2 I had was supposedly used like that. https://w2hx.com/?prefix=x/What-Is-It/PDP-11-Thing/Board1/ what it is, you'd plug your Unibus cable into that pair of connectors on top and run it to whatever Unibus device you were wanting to talk to, potentially another backplane full of Unibus stuff. Commonish upgrade on e.g. CNC machines that were originally controlled by a PDP-11/05 or something in one Unibus chassis, with another Unibus chassis full of machine-specific cards. I spy two AM2901 4-bit slice ALUs, two N82S181 1024x8 PROMs, three AM2911 microprogram sequencers, and an SN74150 3-to-8 line decoder. This thing is doing arithmetic. Carlos.

On Wed, Apr 10, 2024, 7:22 PM Carlos E Murillo-Sanchez via cctalk < cctalk(a)classiccmp.org&gt; wrote: That is not an unusual bit slice architecture for a drive controller. This Dilog DQ419 also has two AM2901 ALUs and three AM2911 sequencers, and what appears to be six microcode PROMs. https://avitech.com.au/?page_id=847