S1130 Emulator has some changes.

Bob Flanders

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Jan 20, 2026, 1:19:42 AMJan 20

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Hi all,

https://github.com/semuhphor/S1130/ has been updated with some new changes. I keep working around the edges (including these changes) which support an S1130 assembler that is similar to a real 1130 assembler but allows more format freedom. Since I might want to write some S1130 assembler then transport it to SIMH, I wrote a converter to go between real assembler and S1130 assembler.

My aim is to get the 1132 code working so I can (Hopefully) boot DMS at some point in 2026.

The new emulator is fully test-driven and it is (kinda) trivial to vibe up a new user interface to run as a web site.

Regards,

Bob

Tom Watson

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Jan 20, 2026, 1:41:25 AMJan 20

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Bob...

Just a note for programming the 1132 printer:
It is very special on timing constraints. I wrote a driver (on a 2.2
machine), and it just barely did the job. I tried to get code to slash
(overprint) zeros, and the extra comparison the the interrupt just
wouldn't work. The interface for the 1403 printer is probably a bit
easier. It has DMA which is a bit easier to simulate, and it only has
one interrupt per line, not a full rotation of 48 of the typewheels.
Regardless, I wish you well on your simulation. Of all the peripherals
on the 1130, the 1132 was probably the most difficult timing wise.
While the 1442 had column interrupts (level 0) it was pretty
straightforward in its interrupt.

Best of luck,

...Tom Watson (trying to remember things from 50 years ago)
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Bob Flanders

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Jan 20, 2026, 1:50:08 AMJan 20

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Hi Tom,

Thanks. I remember it being a bear.

Fortunately, this emulator is not trying to be timing accurate, so it has some wiggle room. Plus, it runs at about 15MIPS.

Thanks for the response.

Regards,

Bob

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John Pierce

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Jan 20, 2026, 2:50:47 AMJan 20

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On Mon, Jan 19, 2026 at 10:41 PM Tom Watson <t...@johana.com> wrote:

Bob...

Just a note for programming the 1132 printer:
It is very special on timing constraints. I wrote a driver (on a 2.2
machine), and it just barely did the job. I tried to get code to slash
(overprint) zeros, and the extra comparison the the interrupt just
wouldn't work. The interface for the 1403 printer is probably a bit
easier. It has DMA which is a bit easier to simulate, and it only has
one interrupt per line, not a full rotation of 48 of the typewheels.
Regardless, I wish you well on your simulation. Of all the peripherals
on the 1130, the 1132 was probably the most difficult timing wise.
While the 1442 had column interrupts (level 0) it was pretty
straightforward in its interrupt.

A guy at my college back in the early 70s wrote a alternate driver for the 1132 which sped it up a fair bit via using predictive timing and stuff. sadly, I have no idea what happened to it. IIRC, it made the 1132 about 20% faster overall.

Bob Flanders

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Jan 20, 2026, 12:36:03 PMJan 20

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That's pretty cool. I can see how that would work. Pre-build your bit strings for the requests that will come from the printer so you can put them out more quickly.

Thanks!

Alex D

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Jan 20, 2026, 1:02:19 PMJan 20

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We need that driver for our museum piece! More visitors to serve with our birthday demo program , more snoopy calendars per minute. 😅.

Alex

iPhone. iTypos. iApologize

Am 20.01.2026 um 18:36 schrieb Bob Flanders <bob.fl...@gmail.com>:

That's pretty cool. I can see how that would work. Pre-build your bit strings for the requests that will come from the printer so you can put them out more quickly.

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