The OS/8 V3D Device Extensions kit (product code
QF026) was released
in December 1978. It was created to support the newest PDP-8 hardware:
KT8AMemory Management option which enables addressing by a factor of four beyond the previous maximum of 32K to a whopping 128K of memory. The highest memory field for a PDP-8a goes up from 7 to 37 (octal).
RL01disk supporting 4 times the previous usual disk capacity, now up to nearly 5 Meg.
RX02double-density floppy disks.
VXNSenables use of
KT8Aextended memory as a file oriented system or non-system device.
This distribution contains software updates:
A version of
BUILD, the system builder that could run under
BATCH. The previous version would just hang.
An update to the OS/8 system including
Keybord Monitorversion 3S, and a version of
ODTthat works with memory fields greater than 7.
ABSLDRversion 6A supports loading into memory fields greater than 7.
PAL8version 13A allows code to specify memory fields greater than 7.
CCLversion 7A updates the 'MEMORY' command to recognize up to 128K words of memory.
PIPversion 14A knows the sizes of the new devices, and has updated how it copies in the monitor system head.
RESORCversion 5A includes new devices.
BOOTversion 5A boots new devices.
RXCOPYversion 4B formats and copies single and double density floppies.
FUTILversion 8A recognizes new core control block format that can represent extended above field 7.
The OS/8 V3D Device Extensions User's Guide can be found in Willem van der Mark's PDP-8 doc archive, under OS/8 - Device Extensions - User's Guide - December 1978 AA-D319A-TA.pdf. or on the ftp.dbit.com pdp8 doc archive at devextug.doc -- OS/8 Device Extensions User's Guide
The release notes can be found on ftp.dbit.com at devextrn.doc OS/8 Device Extensions Release Notes .
Details on how the
KT8A Memory Extension hardware works, physically
and programatically, can also be found at Willem van der Mark's site:
vandermark.ch ... Emulator.128KMemory/EK-KT08A-UG_jul78-ocr.pdf.
When reference is made to
PAL8 version 13, that version originally came
from this kit.
The distribution DECtape for this kit, part number
not yet been found. The PDP-8 Software Components Catalog July 1979
gives no part number for a Source DECtape distribution of this kit.
There is an RK05 source distribution, part number
AN-H529A-SA. However, plausable source and binary have recently been
The binaries were on someone's local hard disk and not published to
the net anywhere I could find. Sadly those binaries did not include
the DECtape's system area, and so the updated version of the OS/8
Keyboard Monitor, Command Decoder and
ODT seemed lost until a tape
could be found. It appears that the original source of these .en files
is Johnny Billingquist's site, ftp.update.uu.se ... dectape1.
Then, however, a self-extracting archive called,
found on a mirror site of ibiblio.org, [rtk.mirrors.pdp-11.ru
... fromhichols][rtknicnols]. Mainline ibiblio.org didn't have it, perhaps it was
purged because of its
.exe extension. The archive is also available
directly from ftp.update.uu.se ... fromnichols, but at slow speed.
When that archive was extracted, the manifest of source files corresponds exactly to the manifest of binaries in the Extensions Kit file archive are present. This looks quite promising for a future project to upgrade to OS/8 V3D with the Device Extensions software, and to create system packs useful even on PDP-8a hardware with 128K words of memory!
After comparing sources found for OS/78, and OS/278, as well as Willem van der Mark's locally modified sources labeled OS/8 version 4, I have moderate confidence that these sources will enable validation and integration of most, if not all the OS/8 V3D Device Extensions functionality.
This validation has been done with regards to
MACREL v2 tape shipped with version 8A of
FUTIL. That was
necessary because V2 of
MACREL supported the latest memory
expansion, and so the OS/8 Core Control Block format needed to change.
FUTIL version 8A integrated patches for
FUTIL version 7 into the
source. Finding those patches in the version 8A source strongly
increased my confidence in those patches.
FUTIL.SV verson 8A executable was saved
incorrectly and then shipped. The Core Control Block setting and
starting address were mis-specified. So
FUTIL version 8A hangs
when run under
The April-May 1979 issue of PDP-8 Digital Software
News contained patch
35.13.1M which fixed this problem and upgraded
FUTIL to version 8B. I've confirmed both the problem and the fix.
Currently if you opt in to having
MACREL on the system packs, you
MACREL v2 and
FUTIL version 8B. If leave
MACREL out, you get
FUTIL version 7. The automated pack builder recognizes that the
version 7 patches won't apply to version 8, and fails to apply them.
The research I did on the OS/8 Device Extensions kit and on
MACREL increased my confidence about the
FUTIL version 7 patches.
See also our documentation on the
and [our documentation on applying OS/8 patches][patchdoc].
Copyright © 2017 by Bill Cattey. Licensed under the terms of the SIMH license.