Someone -- post the wire wrap info... bill +---------------------------------------------------------------------------+ | Bill and/or Carolyn Pechter | pechter(a)shell.monmouth.com | | Bill Gates is a Persian cat and a monocle away from being a villain in | | a James Bond movie -- Dennis Miller | +---------------------------------------------------------------------------+

Jerome Fine replies: This is good news indeed. I was worried that the addition of the extra address lines in an AB/AB or Q22 backplane could damage the CPU. In the BA23/BA123 boxes which are the usual backplanes that are available, the first 3/4 slots are ABCD. Well, I always thought that RSX and RSTS/E were far better of with more memory. Also, with V5.0 of RT-11, the availability of 4 MBytes and a VM: was highly useful - not needed, but very nice. Of course, until recently, DEC memory boards were so expensive that more than 1/4 MByte was not worth while in any case as opposed to SIMMs with the PC. However, a half MByte board (M8067) is now so inexpensive that it is no longer a problem. What hardware did you use to connect the RQDX3 to the RX50/RX33 floppy drives? In general, I found the floppy to be far too slow and if I was jumping up the an RX33, for the same price (at current cost for a hard drive) I would prefer at least an RD51. You can always power the disk drives with an auxiliary power supply from a PC. In that case, you can even have 2 hard drives and 2 floppies. Otherwise, with just the one hard drive (under the tube), it is indeed on the edge of the PS if the VT103 supplies all the power. One other option I mentioned is that a SIGMA RQD11-B (MFM controller) uses about the same power as an RQDX3, but has BOOT ROMS. As a result, you can use just the dual 11/23 and no BDV11. Then there is enough internal power to run everything for a reasonable period of time (likely at least an hour), but if you want a longer period of time or you are going to use 2 hard drives, then stick the hard drives on the eternal PC power supply. YES!! If run for a long time. But for short demos of an hour or less, the VT103 was highly effective. Most individuals who were familiar with the VT100 did not recognize the VT103. So when the demo was given, the first reaction was to ask about the computer - they saw only a VT100. We used to say that we had substituted clever squirrels inside the VT100 instead. I even heard that someone had re-wired the backplane to allow a MicroVax II (ABCD slots for the first 2). Now imagine if DEC had sprung the VT103 on the PC world as a PC at PC prices with a 150 watt power supply (and a bigger fan) to easily allow hard drives under the tube. And later, had gone to the MicroVax II as a standard option. The 10 year late DEC PCs would have been initially based on the PDP-11 and could then have used the VAX. The only thing lacking was a pricing model to compete with the XT and the AT (and a will by Ken Olson to sell to the masses). I understand that a total of 32 solder connections are required. I once saw the re-wired backplane. It seemed to have been done with wire-wrap wire since the solder points were so small. It does not seem that more than a few others use the PDP-11 to any extent and even fewer use RT-11. I guess that perhaps I still quality to be part of the group who fix hardware since I was involved in the VT103 conversion. At one stage, there was a consideration of if it was worthwhile to put an ESDI hard disk controller into the VT103 and use an ST8760E 5 1/4" hard drive, naturally with an external power supply and a fan right beside the drive. In RT-11, that is 20 partitions. SIGMA made an RQD11-DESDI dual controller which could handle 2 of the drives. Sincerely yours, Jerome Fine RT-11/TSX-PLUS User/Addict Year 2000 Solutions for Legacy RT-11 Applications (Sources not always required)