SBC6120 PDP-8SBC6120 PDP-8
What can you actually DO with
an SBC6120 PDP-8 system?


Blinking lights may be fun for a while, but what more is there?
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While GRC has been collecting the names of people who would be interested in acquiring the parts needed to recreate the PDP-8 system I have shown on these pages, interested people have asked what more can be done with the resulting system beyond making the lights blink.

Readily available software for the SBC6120 PDP-8 includes
the well documented OS/8 operating system, complete with
text editors, BASIC, FORTRAN II & FORTRAN IV compilers, a
FOCAL language interpreter, a large assortment of games,
puzzles, simulations & demonstrations, with source code,
and even a well-documented PDP-8 CHESS (human versus
computer) and the classic “Colossal Cave” game “Adventure.”

The PDP-8 was so beloved, popular, and successful for its time, that a large community of enthusiasts have worked to keep the memory — and the software and documentation — alive. When the Internet came along, many hard core collectors put everything they had been saving online.

What that means for those of us who have newly minted, fully PDP-8 compatible systems, is that there is documentation for everything, and we get to play with and experiment with all of the software that was created 40 years ago. It still works today just like it did back then.

Here is Digital Equipment Corporation's (DEC) official
license to use their OS/8 PDP-8 software, with their
blessing, for non-commercial purposes:

DEC's Hobbyist License
All the documentation you'll need
Software is only as useful as our ability to use it, and complex software such as a classic command-oriented operating system, and classic languages having complex and powerful syntax, need documentation so that we're able to accomplish our goals. Here's a sample of what's readily available to support your exploration into the history of PDP-8 operation and usage:

OS8 Handbook PDP-8 Small Computer Handbook OS8 System Reference Manual MACRO-8 Programming Manual 4K FORTRAN Programmers Reference Manual FOCAL Booklet
  • The PDP-8/e Small Computer Handbook (1972, 597-page PDF, 27 MB)

    This is the classic reference for the PDP-8. But more than that, as you will see, the first portion of the book provides a very interesting walk down memory lane. It captures the feeling and the spirit of the day when computers were a new phenomenon and DEC was boasting that they had sold 12,000 of them. This book deeply documents every aspect of the operation of the PDP-8. Armed with it, you can literally "toggle in" small programs and watch them run.
  • The OS/8 Handbook (1979, 500-page PDF, 17.5 MB)

    This OS/8 Handbook (technically the OS/78 Handbook for the latest information) goes well beyond a reference manual just for OS/8. Since the operating system includes the companion editors, assemblers (3), BASIC, FORTRAN II & IV compilers, plus all the required utilities, you'll find them all covered here with sufficient detail to put them to immediate use.
  • OS/8 System Reference Manual (1973, 202-page PDF, 7.4 MB)

    This is an early version of the OS/8 manual, presented mostly for historical nostalgia.
  • FOCAL Intro Booklet (31-page PDF, 255 KB)

    FOCAL (FOrmula CALculator) is the very slick and powerful interactive (BASIC-like) language interpreter DEC designed for the PDP-8. It's part of the OS/8 package
  • FOCAL Reference Manual (1978, 100-page PDF, 3.4 MB)

    This is a complete reference for DEC's FOCAL interpreted PDP-8 language.
    (See the previous link for a quick overview of FOCAL.)
  • OS/8 BASIC Reference Chapter (58-page PDF, 2.3 MB)

    This is chapter six from the OS/8 Handbook. It gives a quick sense for the extensive and thorough nature of DEC's documentation.
  • 4K FORTRAN Programmer's Reference Manual (1969, 84-page PDF, 1.7 MB)

    OS/8 includes two FORTRAN's, a FORTRAN II and FORTRAN. The 4K FORTRAN is a standalone FORTRAN designed to allow development and execution of useful FORTRAN systems on a “bare minimum” PDP-8 with only 4K of core (yes core!) memory.
  • MACRO-8 Programming Manual (1969, 78-page PDF, 1.7 MB)

    Although OS/8's PAL8 assembler has superseded the MACRO-8 assembler, since PAL8 was designed with many of the features from MACRO-8, this detailed 78-page manual provides additional useful background.
  • Chess Program for the PDP-8 Manual (8-page PDF, 20 KB)

    The provided disk partition images include a complete human vs PDP-8 Chess program. This documentation explains its use so you can have fun pitting your wits against a 50 year old program!

In case you haven't yet taken the time to poke around the Internet to get a feel for how much of the PDP-8 legacy has been preserved, here are a few online repositories to give you a sense for how much more is still available to enrich your PDP-8 experience:

What's on the files we provide for the SBC6120?

Note that I will be tweaking the exact content of these two file sets to add additional files (there's plenty of room in each) pulling things together like the OS/8 PASCAL compiler, etc.


The Main OS/8 SBC6120 System Boot Partition
os8dir
Here is a detailed listing of the OS/8 SBC6120 System Boot Partition:
ABSLDR.SV   5	Absolute Loader
ADDEX .FC   2	FOCAL "Addition Exerciser" for elementary school kids
AXIS  .RL   6	FORTRAN IV Plotter Axis drawing library
BARON .FC   6	FOCAL Be the "Baron" of a town - manage resources
BASIC .AF   4	BASIC runtime arithmetic functions overlay
BASIC .BA  11	A rather odd BASIC "interactive" therapist
BASIC .FF   4	BASIC runtime file function overlay
BASIC .SF   4	BASIC runtime string functions overlay
BASIC .SV   9	BASIC language editor
BASIC .UF   4	BASIC runtime user functions overlay
BATCH .SV  10	BATCH (script) processing utility
BCOMP .SV  17	BASIC language compiler
BITMAP.SV   5	Builds a core memory bitmap
BLOAD .SV   8	BASIC compiler post-processor
BOOT  .SV   5	Boots specified device
BRTS  .SV  15	BASIC Runtime system
BTLSHP.FC   7	FOCAL Game of Battleship (requires Tek terminal)
BUILD .SV  33	OS/8 build utility to link drivers
CALNDR.FC   3	FOCAL Perpetual Calendar: day of week for any date
CATLOG.FC   3	FOCAL Catalog of all FOCAL programs shown below
CCL   .SV  18	"Concise Command Language" keyboard monitor extension
CHESS .SV  15	Chess Game?
CHISQR.FC   5	FOCAL CHI Square statistics calculations
COMMA1.RE   6	Part of FOCAL help system
COMMA2.RE   4	Part of FOCAL help system
COMMA3.RE   6	Part of FOCAL help system
CREF  .SV  13	Cross Reference utility
DIRECA.RD   6	Part of FOCAL help system
DIRECI.RD   4	Part of FOCAL help system
DIRECR.RD   4	Part of FOCAL help system
DIRECT.SV   7	DIRectory printing command
EABRTS.BN  24	Something-or-other Runtime System
ECHO  .SV   2	"ECHO" program
EDIT  .SV  10	Symbolic text editor
EPIC  .SV  14	"Edit, Punch, Compare" utility program
ERASE .FD   1
F4    .SV  20	FORTRAN IV compiler - Pass 1
FADTES.FC   1	FOCAL Short exerciser for the FOCAL FADC() function
FBOOT .SV   2
FDIS  .PA   8	Plotting Routines, PAL source
FOCAL .BN  17	FOCAL absolute binary code module
FOCAL .TM   1	Part of FOCAL help system
FOCDEF.PA   4	FOCAL EQUivalent definitions file
FOCINT.PA   9	FOCAL Initial Dialog, PAL source
FOCLIB.PA  69	FOCAL Library Routines
FOCOVR.PA  28	FOCAL Overlay PAL source
FORLIB.RL 165	FORTRAN runtime library
FORT  .SV  25	FORTRAN II compiler
FOTP  .SV   8	"File Oriented Transfer Program"
FRTS  .SV  26	FORTRAN runtime system
FUNCT1.RE   6	Part of FOCAL help system
FUNCT2.RE   5	Part of FOCAL help system
FUTIL .SV  26	File Utility?
GRAPH .FC   5	FOCAL Euclidean graph of 2D equation on Tek terminal
HANGMN.FC   5	FOCAL Plays the game of hangman using HANGWD.FD file	
HANGWD.FD   2	Word list used by FOCAL HANGMN.FC (Hangman) program
HANOI .FC   5	FOCAL Classic "Towers of Hanoi" puzzle solver
HARMON.FC   4	FOCAL "Harmonograph" (Spirograph) drawing
HELP  .FC   6	FOCAL HELP SYSTEM (while in FOCAL, enter: L G HELP)
HELP  .HL  55	Help file data
HELP  .RE   6	FOCAL HELP SYSTEM program code
HELP  .SV   8	Help program
HELPER.RE   2	Part of FOCAL help system
HERROR.RE   6	Part of FOCAL help system
HFILE1.RE   6	Part of FOCAL help system
HFILE2.RE   6	Part of FOCAL help system
ID01NS.BN   1	SBC6120 OS/8 IDE device driver
ID01S .BN   1	SBC6120 OS/8 IDE device driver
INDEX .RE   6	Part of FOCAL help system
INITAL.BN   7	FOCAL module, initial setup dialog and configuration
INTRST.FC   3	FOCAL prints interest, payments, principal, etc.
LIB8  .RL  29	FORTRAN IV code librarian
LIBRA .SV  11	FORTRAN IV code module librarian
LIBRAR.RE   6	Part of FOCAL help system
LINE  .RL   3	FORTRAN IV Plotter Line drawing library
LISTAL.FD   4	FOCAL data file for LISTAL.FC program to list all
LISTAL.RD   4	FOCAL The FOCAL command: 'O I LISTAL' dumps all progs.
LOAD  .SV  15	FORTRAN IV relocatable program loader
MAP   .SV   5	Display map of OS/8 core memory allocation
MISCL1.RE   6	Part of FOCAL help system
MISCL2.RE   6	Part of FOCAL help system
MISCL3.RE   6	Part of FOCAL help system
NUMBER.RL   5	FORTRAN IV Floating Point Number Plotting Library
PAL8  .SV  19	PDP-8 Assembler for absolute code
PASS2 .SV  20	FORTRAN IV compiler - Pass 2
PASS3 .SV   8	FORTRAN IV compiler - Pass 3
PFOCAL.BN  34	FOCAL interpreter binary module
PFOCAL.SV  26	FOCAL interpreter
PIP   .SV  11	Peripheral Interchange Program (copy, backup, etc.)
PLOTER.FC   5	FOCAL Simultaneously plots any three functions
PLOTLB.RL 195	FORTRAN IV Calcomp Incremental plotter library
PLOTR .FT   2	Sample FORTRAN plotter program source
PLOTR .LD  25	FORTRAN IV Plotter support
POLAR .FC   4	FOCAL Polar graph of 2D equation on Tektronix terminal
PSCALE.RL   4	FORTRAN IV Plotter Scaling Library
RALF  .SV  19	FORTRAN Relocatable Assembler
RESORC.SV  10	"Resource" shows system device resources
RXCOPY.SV   6	Media copy utility
SABR  .SV  24	Symbolic Assembler for relocatable code
SDIREC.RD   2	Part of FOCAL help system
SET   .SV  14	SET command to set system parameters
SPY   .SV   3
STAT1 .FC   6	FOCAL Computes stats of two sample sets
STAT2 .FC   5	FOCAL Uses stats from STAT1.FC to compute more stats
SUMCOM.RE   6	Part of FOCAL help system
SV2BN .SV   3
SYMBO1.RE   6	Part of FOCAL help system
SYMBO2.RE   6	Part of FOCAL help system
TECO  .BN  16	TECO text editor binary file
TECO  .PA 151	TECO text editor PAL8 assembly language source
TECO  .SV  14	More capable text editor
TRIANG.FC   4	FOCAL Computes missing info about a right triangle
VM01NS.BN   1	SBC6120 OS/8 RAM Disk device driver
VM01S .BN   1	SBC6120 OS/8 RAM Disk device driver
WEB   .FC   3	FOCAL Draws a spider and her web
XYPLOT.RL   9	FORTRAN IV Plotter XY plotting library
4801  .PA   8	Plotting Routines, PAL source
4WDMOD.BN   1	FOCAL 4-Word overlap to increase floating point res.
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The OS/8 GAMES Partition
os8dir
Here is a detailed listing of the OS/8 GAMES Partition:
BASIC .AF   4	BASIC runtime arithmetic functions overlay
BASIC .FF   4	BASIC runtime file function overlay
BASIC .SF   4	BASIC runtime string functions overlay
BASIC .SV   9	BASIC language editor
BASIC .UF   4	BASIC runtime user functions overlay
BASIC .WS  39	BASIC compiler intermediate file
BBALL .BA  19	BASIC Baseball simulation
BBALL .SV  14	Compiled Baseball simulation
BBALLA.BA  19	BASIC Baseball simulation II
BBALLA.SV  14	Compiled Baseball simulation II
BCOMP .SV  17	BASIC language compiler
BINGO .BA  13	BASIC Computerized game of BINGO
BLKJAC.BA  22	BASIC "BlackJack" (Las Vegas Style) game	
BLKJAK.BA   7	BASIC EduSystem BlackJack (dealer: Petey P. Eight)
BLOAD .SV   8	BASIC compiler post-processor
BRTS  .SV  15	BASIC Runtime system
BUNNY .BA   7	BASIC Prints a famous and well known "Bunny" head
CALNDR.BA   5	BASIC Prints a 12-month calendar for a year
CHECKR.BA  12	BASIC "Checkers" game
CHEKMO.BN  18	CHESS program binary module
CHEKMO.SV  15	CHESS program for the PDP-8! (see chess.pdf doc)
CHEKMO.WU  34	CHESS program overlay file
CODBRE.BA   9	BASIC Very nice "Mastermind" code breaker game (source)
CODBRE.SV  10	BASIC Very nice "Mastermind" code breaker game
CODMAK.BA   8	BASIC A simpler "Mastermind" game (source)
CODMAK.SV   9	BASIC A simpler "Mastermind" game
CRAPS .BA   8	BASIC game of "Craps" (dice)
CUBIC .PA  35	3D Tic-Tac-Toe PAL-8 assembly language (sourcecode)
CUBIC .SV   8	3D Tic-Tac-Toe PAL-8 assembly language
DICE  .BA   2	BASIC Dice rolling simulation
FOOTBA.BA  19	BASIC Football game simulation (sourcecode)
FOOTBA.SV  16	BASIC Football game simulation
FOOTBL.BA  23	BASIC Football game simulator
FOTBAL.BA  21	BASIC Rather sophisticated Football Simulation
GOLF  .BA  17	BASIC "Maynard Country Club" Golf course simulation
HELLO .BA  11	BASIC Rather odd interactive "conversation" program
HELP  .HL 102	HELP source file for OS/8 and several games
HOCKEY.BA  16	BASIC Hockey simulation
K12DEB.SV   4	KERMIT-12 terminal communications module
K12DEC.SV   5	KERMIT-12 terminal communications module
K12ENB.SV   4	KERMIT-12 terminal communications module
K12ENC.SV   6	KERMIT-12 terminal communications module
K12MIT.SV  33	KERMIT-12 terminal communications program
KING  .BA  23	BASIC Kingdom management simulation, you are king
LIFE  .BA   5	BASIC Conway's Game of "Life" simulation
LIFE2 .BA   7	BASIC "Competitive Life" (based on Conway's Life)
MONPLY.BA  22	BASIC The Game of Monopoly
MORTT .FT   7	FORTRAN Mortgage Amortization Table Generator (source)
MORTT .SV  21	FORTRAN Mortgage Amortization Table Generator
NIMBLE.BA  12	BASIC The classic game of NIM (source)
NIMBLE.SV  13	BASIC The classic game of NIM
OTHELO.BA  21	BASIC The game of Othello (source)
OTHELO.SV  16	BASIC The game of Othello
POKER .BA  20	BASIC Play POKER against the machine
RESEQ .BA   6	BASIC "Resequence" line numbers in BASIC source file
ROCKET.BA   6	BASIC Apollo Lunar Landing Simulator (source)
ROCKET.SV   8	BASIC Lunar landing simulator (executable)
ROCKT1.BA   8	BASIC David Ahl's Lunar Landing Simulator
ROULET.BA  11	BASIC Game of Roulette. Start with 100 chips
ROULET.SV  10	BASIC Roulette simulator
SIGNS .BA  19	BASIC Large Sign Printer
SNOOPY.BA  10	BASIC "Curse You Red Baron!" Snoopy Printer
SPACWR.BA  39	BASIC Star Trek Space Adventure Simulation
STARTR.BA  31	BASIC StarTrek space simulation (source)
STARTR.LS   4	Star Trek Simulation Documentation (TYPE this file)
STARTR.SV  28	BASIC StarTrek space simulation
T3BZSR.SV  17	Appears to be some sort of tic-tac-toe game
T3ZSR .SV  17	Appears to be some sort of tic-tac-toe game
TD81  .BN   2	Assembled binary for TD81.PA
TD81  .PA  20	TD8E system resident handler for OS/8
TD82  .BN   2	Assembled binary for TD82.PA
TD82  .PA  20	TD8E handler for OS/8
TD8E  .SY  50	TD8E DECtape controller device driver
TICTAC.BA   7	BASIC Tic-Tac-Toe - play against the machine
WAR   .BA   7	BASIC Simulation of the card game of WAR
WAR2  .BA   9	BASIC Army/Navy/AirForce warfare simulation
WEKDAY.BA  10	BASIC Interesting facts about any date you enter
WUMPUS.BA  17	BASIC Classic "Hunt the Wumpus" game
YAHTZE.BA  20	BASIC Game of Yahtzee implementation
YAHTZE.SV  20	The game of Yahtzee
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Common file extensions used by standard OS/8 files
.BA	BASIC source file
.BI	BATCH input file
.BN	Absolute binary file
		Output from PAL8 assembler
.CM	Command File
.DI	Directory Listing
.F4	FORTRAN IV source
.FC	FOCAL8 (DEC's "FOrmula CALculator" language)
.FT	8K FORTRAN source file
.HL	Help File Data
.HN	I/O Device Handler Save Image
.LD	FORTRAN load module
.LS	PAL8 and SABR assemblers output listing
.MP	Linking Loader Map file
.PA	PAL8 (assembly language) source file
.RA	RALF - FORTRAN intermediate assembly source
.RL	Relocatable binary file
		8K SABR output
		Linking Loader input file
.SB	8K SABR (assembly language) source file
.SV	A directly executable "core image" "SAVE" file
.TM	BASIC/FOCAL intermediate temporary file
.WS	BASIC compiler intermediate

In Conclusion

As you can see from the extensive available documentation, and the file directory details, the contemporary SBC6120 PDP-8 system can function every bit as capably as any DEC PDP-8 did when its paint was still fresh in the late 1970's.



GRC's PDP-8 Pages:
CLICK HERE to learn how YOU can acquire & build
one of these complete PDP-8 systems for yourself !!!

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Last Edit: Jan 28, 2010 at 13:21 (2,706.30 days ago)Viewed 12 times per day