Collections:thinning out

The smallest Qbus backplane is one that fits into a VT100 which is then called a VT103. This backplane is 4 dual slots and just barely manages. There is also a 4 quad slot version which is likely no more expensive these days if you can find one - most likely free from an individual who has graduated to a BA23 box. There are also independent backplanes with power supply and 4 quad slots, but these are probably harder to find now than a BA23 box and probably only half the size and weight of a BA23.

There are a number of sites which offer PDP-11 distributions. The site that I used for RT-11 was: http://www.classiccmp.org/PDP-11/RT-11/dists/ which offers V04.00, V05.03 and ALL (well probably most) of the binary RT-11 versions up to V05.03 of RT-11. If you want to learn about RT-11, then the simple way is to use an emulator running on a PC. Ersatz-11 (which I use most of the time) is free to hobby users and SIMH is free to everyone as far as I understand, although that may not be the case. But with Ersatz-11 being much less than the cost of real DEC hardware when DEC was selling it, any commercial user will run under Ersatz-11 since it is about ten times the speed of SIMH which is written in C.

If you need help in running RT-11 after you download an RT-11 distribution, please ask.

Not after your programs become large enough. The maximum program under RT-11 using VBGEXE is 64 KBytes. Under the SJ unmapped monitor, programs must be much smaller.

RT-11 distributions are complete with editor, assembler and linker. There are many utility programs to copy files. Languages such as C and FORTRAN are available as well. These are called layered products. The manuals for RT-11 are available at bitsavers. The hardcopy is THREE feet of manuals in binders. All of the PDF files are available in 21 files of a total of 12.5 MBytes.

It is usually the data that becomes too large. I have a program that sieves for prime numbers. Under Ersatz-11, the program has direct access to the PC memory of over 1 GigaByte and more memory would be better. The actual code is very small, but when sieving for prime numbers, a larger work space helps. I should probably switch to a program directly on the PC, but I enjoy working in RT-11. I am in the midst of a slow (more than a year) move to Windows XP on an Intel Q9500 quad 2.83 GHz CPU which runs RT-11 about 100 times as fast as a PDP-11/93 for the CPU and about 200 times as fast as a SCSI or ESDI hard disk drive using a SATA 300 hard drive of 1 TB. That provides a lot of storage as compared to a 600 MB Maxstore or Hitachi ESDI hard drive which is what I run on the PDP-11/83 out of a BA123 box.

Sincerely yours, Jerome Fine