Subject: Re: [SPAM] - Re: Simulated disk drive for RT-11? - Sending mail serverfound on relays.ordb.org From: "Jerome H. Fine" <jhfinexgs2 at compsys.to> Date: Wed, 08 Jun 2005 22:05:18 -0400 To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> Jerome Fine replies: If you want to add one more backplane to your list, I used a 2 * 22 slot Qbus Q22 bit backplane when I did some Y2K bug fixes for some application programs. Specifically, this was a 22 slot backplane with ONLY dual slots, obviously all AB. The last slot had extra room to allow for a board of about 2" that held a small SCSI hard drive of about 100 MBytes. The 3rd last slot (and the 2nd last which it overlapped) help a 3 1/2" floppy or an RX23. There was a CQD 220/TM with special ROMs which supported the RX23 as a standard device with removable media. By the way, the power supply was not part of the box holding the backplane - they (power supply and backplane) were connected by a short 3 foot cable. I think that the ONLY DEC board was the M8192-YB CPU.

As for one more backplane, I presume that you have the 4 * 4 slot (4 quad slots) for the VT103 which were sold with 18 bits, but could be upgraded in the field to 22 bits. At one point, I heard that someone made the first 2 slots AB / CD and installed a uVAX-II. That was beyond my ability, I only used an M8190-BB and a 4 MByte memory board with a CDQ 220/TM and a DHQ11.

Those days fooling with the hardware were fun, but now that there are emulators that can run about 100 times the speed of a PDP-11/73, for an RT-11 software addict like myself, the hardware has become much less important.