# Digital Equipment Corporation
DOS-15 V2A

## Contents

Introductuion
Installation
Documentation
Line Priner
Prebuilt RF Disk Image
8 Platter Disks
Disk Packs
Software

## Introduction

DOS-15 was a disk based operating system developed from the DECtape based PDP-9 ADSS. Despite the names of these systems, they both work on PDP-9's and PDP-15's.

DOS-15 was thought to have been lost, but while examining a batch of DECtapes which were associated with a PDP-9 we were restoring, I came across 3 tapes labelled as being an update to the DOS system. These tapes are most likely archive copies of a users system. The three update tapes tapes were dumped to file images and analysed. update1.png, update2.png and per.png asre scans of the the tapes we found showing the labelling.

A second pair of tapes, labelled with the DEC numbers identifying the original release are yet to be recovered.

With hints from various documents, the format of the tape images was established as being DOS dump tapes. No copies of the paper tape program DOSSAV used to restore such tapes to a disk image have so far been found, but a C program was written to perform this function.

With a DOS image disk in hand, we faced the problem of booting. No copies of the DOS bootstrap have so far surfaced. It was noticed that the boot process of ADSS and of DOS were quite similar and that the interface to the DECtape ADSS bootstrap was identical to that described for the DOS bootstrap. We therefore adapted the source code of the ADSS RF bootstrap and after a couple of tries managed to make it boot DOS.

After fixing a couple of minor emulator bugs we had a working DOS system!

Anyone with copies of the missing pieces: the DOSSAV and original bootstrap paper tapes and documentation are urged to contact me with a view to making them available on this archive.

## Installation

Note : You will need SIMH version 2.10-3 or later to run DOS-15.

Recover the 1.2 MB archive zip fileand uncompress into a directory. Change to that directory and ensure that the SIMH executable for the PDP15 emulator is accessible.

DOS-15 was distributed on two DECtapes or a mag tape. This is the DECtape release. The two files UPDATE1.DTA and UPDATE2.DTA are SIMH DECtape image files of the two tapes. There is a third DECtape called PER with some auxiliary files.

UPDATE1 and UPDATE2 are dump tapes of a 1 platter DOS system. To build a disk image, compile DOSSAVE (or use the prebuilt Windows .exe) and run it as follows

          DOSSAVE [p] <tape-name> > <disk-name>

where the optional parameter p specifies the number of RF platters, the default is 1, the maximum is 7. (See the section 8 Platter Disks for how to build an 8 platter disk).

The tape name should be UPDATE1.DTA for the first tape. At the end of the first tape, DOSSAVE will change the 1 to a 2 and read the second tape.

Output from DOSSAVE is to stdout and should be redirected to an RF image file, e.g., to set up a 2 platter DOS disk image run as follows:

          DOSSAVE 2 UPDATE1.DTA >DOS_2P.RF

The DOS bootstrap file, RFSBOOT.RIM, is a reconstruction, since an original copy has not yet been found. The assembler source to the bootstrap is provided in the file RFSBOOT.ASM.

Check the DOS.INI file for correct file names and paths and then boot DOS by issuing the command:

          PDP15 DOS.INI

DOS should boot and ask for the date. I use 1973 as a year so as not to confuse DOS with Y2K and other date issues.

Note that the INI file has attached the file CHECKOUT.BT to the PTR. This file is typed in from a DEC manual. CHECKOUT was also shipped as a papertape with DOS systems. It excersies the DOS system and ensures that it is working correctly.

To run the checkout, issue the following command at the DOS $ prompt:

          BATCH PR

The procedure will perform some PIP transfers and then compile a Fortran program and assemble a macro file, then link and execute the resulting program. I have found it instructive to study the commands issued.

## Documentation

The following lists available documents relating to the PDP-15 software.

The PDF links are direct to the web version of that manual. 'ACONIT' indicates that a printed version of the manual is in the ACONIT collection.

Document tile | DEC Reference | Date | Available
--- | --- | --- | ---
Macro-15 Assembler, Programmer's Reference Manual | DEC-15-AMZA-D | Oct 1969 | PDF 4.4 MB
Macro-15 Assembler, Programmer's Reference Manual | DEC-15-AMZB-D | Sep 1972 | ACONIT
FORTRAN IV | DEC-15-KFZB-D | Sep 1972 | PDF 4.1 Mb
PDP-15 FOCAL, Programming Manual | DEC-15-KJZB-D | Oct 1970 | ACONIT
Advanced Monitor Software System for PDP-15/20/30/40, Programmer's Reference Manual | DEC-15-MR2B-D | Dec 1970 | PDF 8.7 MB
Background/Foreground Monitor, Programmer's Reference Manual | DEC-15-MR3A-D | Apr 1972 | PDF 11.7 MB
DOS-15 Assembly Parameters | DEC-15-ODAPA-A-D | Aug 1974 | PDF 773 KB
DOS User Manual | DEC-15-ODUMA-A-D | Dec 1972 | PDF 13 MB
DOS System Manual | DEC-15-ODFFA-A-D | Jul 1972 | PDF 6.3 MB
Utility Programs Manual | DEC-15-YWZA-D | Oct 1969 | PDF 8.5 MB
SGEN System Generator | DEC-15-YWZA-DN3 | Sep 1970 | PDF 3.5 MB
SGEN-DOS utility program | DEC-15-YWZB-DN12 | Oct 1971 | PDF 6 MB
PIP DOS monitor utility program | DEC-15-YWZB-DN13 | Apr 1972 | ACONIT

## Line Printer

The LPA.;BIN driver in the <IOS> directory of the release is an LP09 driver. The system skip chain is not gen'd correctly to support that printer and any attempt to use the printer will result in an IOPS5 error.

To fix this issue, run the LPA.BT batch which will install the new LPA15 driver.

This process starts at the SIMH prompt by attaching the batch tape image file to the PTR and the PER tape image to DT1 :

    > at -a ptr lpa.bt
    > at dt1 per.dta
    > cont

At the DOS $ prompt issue the following command :

       $ BATCH PR

The printer driver will be assembled and copied to its correct place on the system disk replacing the previous, incorrect version.

## Prebuilt RF Disk Image

The distribution includes a prebuilt 4 platter RF disk image of DOS-15. The line printer driver fix has already been applied. To use this image, start the PDP-15 simulator and issue these commands:

    > at -e rf dosv2a_4p.rf
    > load rfsboot.rim 77637
    > run

DOS should boot and ask for the date, as described above.

## 8 Platter Disks

During the process of bringing up DOS V2A we noticed that it would not work on an 8 platter RF system. The system would boot to the $ prompt and all resident commands worked but any attempt to load a program resulted in an IOPS21 error : invalid disk address.

Investigations of this error led to a patch to the resident binary image on the first DECtape image. With this patch, we could successfully load programs but now any attempt to use any of the three DK drivers provoked the IOPS21 error again.

We determined that there are, in effect, 4 DK drivers on the system tapes, the first being in the resident image, the other three being the DKA.;BIN, DKB.;BIN and DKC.;BIN files in the <IOS> directory. Each of these drivers have the same bug: they declare an IOPS 21 error when they determine that the number of platters on the RF subsystem is greater than 7. As far as we can tell this is bug was extant at the time of the release from DEC implying that no user had an 8 platers system and further that DEC never tested such a configuration.

The patch we developped for the resident image was adapted for the DK drivers, a problem complicated by the fact that the DK drivers were relocatable object files, not pure binary load images. The file 8P.BT is the result.

The procees to make an 8 platter RF image is as follows:

Starting wiht copies of the two DECtape system image tapes, mount the first on DTA1 and the second on DTA2. Attach, in ASCII mode the file 8P.BT to PTR. Boot aworking version of DOS V2A.

At the DOS $ prompt issue the command 'BATCH PR' and verify that the resulting console output corresponds with the listing shown below.

    $BATCH PR

    DOS-15 V2A
    $$JOB
    A DTA1 -14

    $PATCH
    PATCH V10A
    >B 051
    >L 0111
    >00111/615231>741000
     00112/615077>
    >
    >$JOB
    DOS-15 V2A
    $A DTA2 -14

    $PATCH
    PATCH V10A
    >B 0211
    >
    >L 064
    >00064/015000>
     00065/351167>213554
     00066/040404>
     00067/700000>
     00070/707065>
     00071/700000>
     00072/040403>
     00073/700000>
     00074/707001>
     00075/602463>
     00076/040304>
     00077/707242>
     00100/602470>
     00101/707242>
     00102/030303>030304
     00103/343623>
     00104/544224>
     00105/603366>741000
     00106/030304>
    >
    >B 0210
    >L 0150
    >00150/015000>
     00151/502301>334233
     00152/040404>
     00153/750000>
     00154/707045>
     00155/700000>
     00156/040404>
     00157/700000>
     00160/700000>
     00161/707065>
     00162/040404>
     00163/700000>
     00164/700000>
     00165/707001>
     00166/030403>
     00167/602027>
     00170/707242>
     00171/602034>
     00172/040303>
     00173/707242>
     00174/343163>
     00175/543560>
     00176/030303>040303
     00177/602732>741000
     00200/602020>
    >
    >B 0254
    >L 0320
    >00320/015000>
     00321/370124>230443
     00322/040404>
     00323/700000>
     00324/707065>
     00325/700000>
     00326/040403>
     00327/700000>
     00330/707001>
     00331/601165>
     00332/040304>
     00333/707242>
     00334/601172>
     00335/707242>
     00336/030303>030304
     00337/341526>
     00340/542141>
     00341/601320>741000
     00342/030304>
    >
    >
    >

    DOS-15 V2A
    $

At this point exit SIMH and build an 8 platter RF image using the two patched DECtape images:

    C:\SIMH\dos>dossave 8 patched1.dta >dosv2a_8p.rf
    DOSSAVE version 2.0, 12 February 2003
    SAT T :   2000   2000  21703 ...    413 777777
    SAT 2 :  20000   7132      0 ...   1777 777777
    SAT 1 :  20000  10646   1561 ... 777777   1775

Check that a DOSSAVE version message appears and that the version is at least 2.0.

Now restart SIMH using that new image and verify that it is working First load PIP and do a DK listing, verify that

- PIP loads and
- the number of free blocks is 16217

Then set slots 11 and 12 to DKB and DKC and reload PIP If PIP loads then the drivers are patched correctly.

    C:\SIMH\adss15\dos>pdp15 dos.ini

    PDP-15 simulator V2.10-2
    RF: buffering file in memory [2097152]

    DOS-15 V2A
     ENTER DATE (MM/DD/YY) - 2/13/73

    $PIP

    DOSPIP V6A

    >L TT _ DK

         13-FEB-73
     DIRECTORY LISTING  (SCR)
      16217 FREE BLKS
          0 USER FILES
          0 USER BLKS

    >^C

    DOS-15 V2A
    $A DKB 11

    $A DKC 12

    $PIP

    DOSPIP V6A

    >

All done, enjoy your 8 platter RF DOSS V2A system.

## Disk Packs

Using the following sequence you can initialize and empty diskpack and use it for user files.

    > attach rp1 user.rp

    MICLOG SYS
    PIP
    I DPA1
    N DPA1 <USR>
    L TT _ DPA1 <USR>

Currently packs my only be used for user files. DOS-15 system tapes for packs have not been found yet.

## Software

The DOS-15 User Manual explains the operation of the internal monitor commands. Refer to Dos-15 Utilities Manual for information about the various utilities available.

### Fortran & Macro Assembler

See the file

    checkout.bt

for an example of compiling and running programs in Fortarn and in Assembler. It also shows how to link Assembler code to Fortran.

### Focal

FOCAL-15 can be run as follows:

    $ GLOAD

    BLOADER V12A
    >_FOCAL<esc>

    FOCAL V10A
    *TYPE 2+2,!
        4.0000
    *

Refer to the FOCAL-15 Reference Card [1.5 MB] for details of the language.

The PER DECTAPE includes sources to assembler routines which can be called from FOCAL and the user may add their own FOCAL callable routines to the same library.

Last updated 17 Feb 2003 13:20 Email : hansp@aconit.org |