Patching vs. new code (was Re: Pascal not considered harmful)

Chris Elmquist chrise at
Tue Feb 24 20:28:09 CST 2015

On Monday (02/23/2015 at 10:21PM -0800), Michael Holley wrote:
> In 1982 I was working at Data I/O, the PROM programmer company. Everything was written in assembler for the 6800. We had a cross assembler that ran on a PDP11, it was much faster than the Motorola EXORciser that used 8 inch floppy disks. We later updated to a VAX. On one project we had a firm code limit of 16K bytes, every week or so we would have to hand optimize our assembly language so we could keep adding the necessary features. We had about 20 bytes open when we were done.
> I recall that the cross assembler was from a company named BSO.

Yes.  Boston Systems Office...  which later became BSO/Tasking I believe
and now just "Tasking",

They had a whole suite of cross-assemblers that ran on DEC hosts.
I used 6800, 6502 and 8080 versions running on a DECSYSTEM-20 at 3M
around 1979, 1980.

Of course I was using my Dad's login and dialing into the machine over
300 baud modem from my bedroom but they were awesome development tools
compared to locally hosted stuff.

I also used a 6800 cross-assembler earlier, around '76 or '77 running on
a CDC network called CyberNet.  I believe these were actually Motorola
developed cross-development tools hosted on CyberNet, which was a for-pay
timesharing network with I think, world-wide access at the time.

Still, it was pretty cool to be able to edit, assemble, load and run
all your code right on your own machine even if it took forever ;-)

Does anyone have copies of any of the BSO cross-assemblers for any DEC
platforms that we might be able to run in SIMH?


> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Ian S. King
> Sent: Monday, February 23, 2015 9:17 PM
> To: General Discussion: On-Topic and Off-Topic Posts
> Subject: Patching vs. new code (was Re: Pascal not considered harmful)
> My first (paid) programming job was in 6800 assembler, using the Motorola EXORCISER system.  It took hours (as in a major part of a day, longer than the work day) to reassemble the entire code base, so we would patch the program in the PROM programmer.  We would, of course, back port the changes in symbolic assembler to the source, and every few days just take the downtime hit to rebuild the code base.  Keep in mind that this was natively hosted on a 6800 system.
> Another interesting tidbit: its simple filesystem did not segment files and reuse blocks, so you had to purge old versions of files, preferably before a dozen or so files were lined up after it.  In that case, it would tie up the system for way too long while an old file was purged and all the new files were packed into the recovered space, block by block.  It was barely a step above magtape.
> One other note: there was a bug in certain mask sets that required a NOP before you could set the interrupt mask.  Since the ENTIRE memory/IO space was 64k bytes, every byte was sacred, every byte was great, and if a byte was wasted….
> --
> Ian S. King, MSIS, MSCS
> Ph.D. Candidate
> The Information School
> University of Washington

Chris Elmquist

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