PDP-15
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The PDP-15 was an 18-bit minicomputer by Digital Equipment Corporation that first shipped in February 1970.[1] It was the fifth and last of DEC's 18-bit machines, a series that had started in December 1959 with the PDP-1.[2]Template:RP More than 400 were ordered within the first eight months.[2]Template:Rp A later model, the PDP-15/76, was bundled with a complete PDP-11, allowing the PDP-15 to use peripherals for the PDP-11's popular Unibus system. The last PDP-15 was produced in 1979, with total sales of about 790 units.
The PDP-15 was essentially a version of the earlier PDP-9 that was constructed using small-scale integration integrated circuits, which made it smaller and less expensive than the PDP-9's flip chips which used individual transistors. A basic 8 kW PDP-9 cost about $35,000 in 1968 (Expression error: Unrecognized punctuation character "[".), whereas the PDP-15 with 4 kW was only $15,600 (Expression error: Unrecognized punctuation character "[".) and a fully-equipped system with 8 kW, punch tape, KSR-35 terminal, math coprocessor and dual DECtape was $36,000 (Expression error: Unrecognized punctuation character "[".), making a complete system significantly less expensive than the earlier machine.[3]
In addition to operating systems, the PDP-15 has compilers for Fortran[4] and ALGOL.[5]
History
The 18-bit PDP systems preceding the PDP-15 were named PDP-1, PDP-4, PDP-7 and PDP-9. The last PDP-15 was produced in 1979.[6]
Hardware
The PDP-15 was DEC's only 18-bit machine constructed from TTL integrated circuits rather than discrete transistors, and, like every DEC 18-bit system could be equipped with:
- an optional X-Y (point-plot or vector graphics) display.
- a hardware floating-point option, with a 10x speedup.[7]
- up to 128K words of core main memory[8]Template:Rp
Models
The PDP-15 models offered by DEC were:[9][10][11][7][12]
- PDP-15/10: a 4K-word paper-tape-based system
- PDP-15/20: 8K, added DECtape
- PDP-15/30: 16K word, added memory protection and a foreground/background monitor
- PDP-15/35: Added a 524K-word fixed-head disk drive
- PDP-15/40: 24K memory
- PDP-15/50:[13]
PDP-15/76
- PDP-15/76: 15/40 plus PDP-11 frontend. The PDP-15/76 was a dual-processor system that shared memory with an attached PDP-11/05.[2]Template:Rp The PDP-11 served as a peripheral processor and enabled use of Unibus peripherals.[14]
Software
DECsys, RSX-15, and XVM/RSX were the operating systems supplied by DEC for the PDP-15. A batch processing monitor (BOSS-15: Batch Operating Software System) was also available.[5]
DECsys
The first DEC-supplied mass-storage operating system available for the PDP-15 was DECsys, an interactive single-user system. This software was provided on a DECtape reel, of which copies were made for each user. This copied DECtape was then added to by the user, and thus was storage for personal programs and data. A second DECtape was used as a scratch tape by the assembler and the Fortran compiler.[15]
RSX-15
RSX-15 was released by DEC in 1971.[16] The main architect for RSX-15 (later renamed XVM/RSX) was Dennis "Dan" Brevik.[17][18]
Once XVM/RSX was released, DEC facilitated that "a PDP-15 can be field-upgraded to XVM" but it required "the addition of the XM15 memory processor."[19]
The RSX-11 operating system began as a port of RSX-15 to the PDP-11, although it later diverged significantly in terms of design and functionality.[20]
Origin of the RSX-15 name
Commenting on the RSX acronym, Brevik says:[21] Template:Quote
XVM/RSX
Later versions of the PDP-15 could run a real-time multi-user OS called XVM/RSX, an outgrowth of RSX-15.[11][5] The XVM upgrade to RSX was multi-user, and enabled up to six concurrent teletype-based users.[22] XVM Support for the PDP-15/76 included using an RK05 disk drive.[19]
non-DEC
The MUMPS operating system, which was originally developed in 1966,[6] was developed on the PDP-7 outside DEC. It is also available for the PDP-15.
Application software
DEC provided mathematical, scientific and commercial software application tools.[8]Template:Rp [23]
See also
References
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- ↑ A PDP-15/50, described then as "expensive to maintain," was still running in 1982. Script error: No such module "citation/CS1".
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- ↑ "Commercial Subroutine Package (CSP) ... compatible with the IBM 1130 commercial subroutine package."
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External links
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