And speaking of ALGOL

Jay Jaeger cube1 at
Wed Aug 12 14:28:59 CDT 2015

In addition, B5500/B5700 Mark XIII and B5500/B5700 MARK XV.3 release
tapes can be found online.

UNISYS released these under the "UNISYS MCP MARK XIII SOFTWARE
EDUCATIONAL/HOBBYIST LICENSE AGREEMENT" in 2012, having been approached
by the owner of the tapes.

At least Mark XIII is available on Paul Kimpel's web site.  PLEASE NOTE
THE LICENSE, which was arranged through Unisys (Bob Supnik was the
contact at the time, but he has since retired from Unisys, according to
what I see on LinkedIn).  The history of how that happened is on the web
page, below, along with links to download the tape images.

A Google for "MARK XV.3 BURROUGHS" will turn up the MARK XV.3 tapes as
well.  ;)  I am not aware of a similar license document for that set,
but I suggest it should be considered to exist under at least the same
restrictions ("solely for non-commercial educational or hobbyist purposes").

Anyway, I looked at my listing of the MARK XIII tape SYMBOL1 7 Track BCD
tape image, and it has ESPOL source.  The ESPOL Compiler, version MARK
XIII.0 starts at File 18, dated July 15, 1971.

I'd expect it to be present on MARK XV.3 as well, of course.

Also on the MARK XIII SYMBOL1 tape (Looking at the directory in file 2,
from my same listing)


I don't seem to have ever made a listing of what is on tape SYMBOL2.
How odd.  But, not to worry, a listing of what is on that tape is
available at:


On 8/12/2015 12:39 PM, Nigel Williams wrote:
>> On 12 Aug 2015, at 11:24 pm, Paul Koning <paulkoning at> wrote:
>>> On Aug 11, 2015, at 10:23 PM, Mark Kahrs <mark.kahrs at> wrote:
>>> For those of you who might be interested, I sent a listing of the B6700
>>> ALGOL compiler source code to the CHM.
>>   I did find a copy of the B6500 ESPOL compiler online recently.
> In the B5500 emulator repo:
> It is still to be proofed though.
>>> I'm surprised no one has mentioned the Burroughs extensions to ALGOL to
>>> optimise|ize the use of the native string instructions.
>> Did Algol come after the hardware?  I always thought of the hardware as having been customized for their Algol, but admittedly I don’t actually know which is chicken and which is egg.
> It is suggested in the oral history at that the B5000 was designed as an ALGOL machine and Burroughs had the idea that only compilers would generate machine code, so they made the B5000 compiler friendly, and the system would have an OS to manage resources, so it was designed around drum/disk being an intrinsic part of the system.

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