Clarification - I'm learning Ada language and using the 642 as a target to program.

Slow going since:
A) Learning a new programming language
B) Missing some bits of information on the system(s)

At the moment, I think I have the basics of the CP642/Univac 1212 enough to do a basic emulator with some caveats.

Current missing info:

- ECMU mods assume (!) using 1230 instructions for extended memory access since I can't find any CDC documents on ECMU mods
- For skip mods, during shifting/addition/subtraction, is the skip check after each bit shift/arithmetic step or after the full shift count/arithmetic operation
- For ECMU extensions, what does the 7707 instruction (normalize) actually do (i.e., where is the result stored or how is it used).

As for history, retired DS1 having worked on the 642B/ECMU while attached to the USS Horne (CG30) in circa 1984.

Side note - I modified the combat systems program on the Horne to check IFF mode and match to battlegroup mode responses, so the ACRO displayed actual vehicle (USS Horne/USS Ranger/VF-242/etc) being hooked.

Another side note - $DAYJOB and $HONEYDOLIST does interfere with full attention on emulator/language learning, so taking a while to get it designed.

ATM - I'm seriously considering a prototype in Python3 (so I can get the basics worked out while learning Ada).

-------- Original Message --------
Subject: Re: Ken Roberts is working on a 642 emulator.
From: Ken Roberts <alisonken1@gmail.com>
To:
Date: Tue Dec 07 2021 13:52:43 GMT-0800 (Pacific Standard Time)

> Clarification - I'm learning Ada language and using the 642 as a target to program.
>
> Slow going since:
> A) Learning a new programming language
> B) Missing some bits of information on the system(s)
>
> At the moment, I think I have the basics of the CP642/Univac 1212 enough to do a basic emulator with some caveats.
>
> Current missing info:
>
> - ECMU mods assume (!) using 1230 instructions for extended memory access since I can't find any CDC documents on ECMU mods
> - For skip mods, during shifting/addition/subtraction, is the skip check after each bit shift/arithmetic step or after the full shift count/arithmetic operation
> - For ECMU extensions, what does the 7707 instruction (normalize) actually do (i.e., where is the result stored or how is it used).
>
> As for history, retired DS1 having worked on the 642B/ECMU while attached to the USS Horne (CG30) in circa 1984.
>
> Side note - I modified the combat systems program on the Horne to check IFF mode and match to battlegroup mode responses, so the ACRO displayed actual vehicle (USS Horne/USS Ranger/VF-242/etc) being hooked.
>
> Another side note - $DAYJOB and $HONEYDOLIST does interfere with full attention on emulator/language learning, so taking a while to get it designed.
>
> ATM - I'm seriously considering a prototype in Python3 (so I can get the basics worked out while learning Ada).
>

I assume you are aware of the documents on bitsavers.org:

http://www.bitsavers.org/pdf/univac/military/

and particularly:

http://www.bitsavers.org/pdf/univac/military/ntds/

http://www.bitsavers.org/pdf/univac/military/1212/

Paul

-------- Original Message --------
Subject: Re: Ken Roberts is working on a 642 emulator.
From: Ken Roberts <alisonken1@gmail.com>
To:
Date: Tue Dec 07 2021 13:52:43 GMT-0800 (Pacific Standard Time)

> Clarification - I'm learning Ada language and using the 642 as a target to program.
>
> Slow going since:
> A) Learning a new programming language
> B) Missing some bits of information on the system(s)
>
> At the moment, I think I have the basics of the CP642/Univac 1212 enough to do a basic emulator with some caveats.
>
> Current missing info:
>
> - ECMU mods assume (!) using 1230 instructions for extended memory access since I can't find any CDC documents on ECMU mods
> - For skip mods, during shifting/addition/subtraction, is the skip check after each bit shift/arithmetic step or after the full shift count/arithmetic operation
> - For ECMU extensions, what does the 7707 instruction (normalize) actually do (i.e., where is the result stored or how is it used).
>
> As for history, retired DS1 having worked on the 642B/ECMU while attached to the USS Horne (CG30) in circa 1984.
>
> Side note - I modified the combat systems program on the Horne to check IFF mode and match to battlegroup mode responses, so the ACRO displayed actual vehicle (USS Horne/USS Ranger/VF-242/etc) being hooked.
>
> Another side note - $DAYJOB and $HONEYDOLIST does interfere with full attention on emulator/language learning, so taking a while to get it designed.
>
> ATM - I'm seriously considering a prototype in Python3 (so I can get the basics worked out while learning Ada).
>

I assume you are aware of the documents on bitsavers.org:

http://www.bitsavers.org/pdf/univac/military/

and particularly:

http://www.bitsavers.org/pdf/univac/military/ntds/

http://www.bitsavers.org/pdf/univac/military/1212/

Paul

On Wednesday, December 8, 2021 at 8:07:20 AM UTC-8, Paul Kimpel wrote:
<snip>
> I assume you are aware of the documents on bitsavers.org:
>
Yes. I already have all of the bitsaver files on ntds as well as some others I've found (including the ECMU mods PDF - which is actually _mostly_ scans of the logic diagrams. MIssing some pages in the pdf and one of the files is actually a duplicate of the other one - not very helpful.)

What I'm looking for is the theory of operations files for the 642. The original intent was to emulate the functions of the 642, not just emulate the ISA.

It looks like I'll have to emulate the ISA with guestimates on some functionality:

- Does skip on negative abort the shift instruction as soon as bit 29 is set, or does it shift the full count and then evaluate skip on negative.
- Arithmetic instructions are 1's complement subtractive, but it apparently also does borrow look-ahead - which affects step counting on detecting under/overflow instruction aborts

So, take the emulation with a grain of salt until I can find answers to these (and other) questions.

On Tuesday, December 14, 2021 at 8:11:03 AM UTC-5, aliso...@gmail.com wrote:
> So, take the emulation with a grain of salt until I can find answers to these (and other) questions.

There are some old Univac Navy types on MeWe. They might be able to help.

https://mewe.com/group/5fd552d31f79902b9084908f