[cctalk] Re: programming the IBM PC synchronous serial boards (Northstar Advantage project)

[Mattis Lind via cctalk]

On Friday, December 22, 2023, r.stricklin via cctalk 
wrote:

> Did IBM ever publish programming information for their PC SDLC or BiSync
> communications boards? I’m wondering about the possibility of programming
> one to drive the synchronous protocol needed for “booting” a Northstar
> Advantage over its serial port.
>
> Or, for that matter, wondering what Northstar had in mind when they made
> that protocol synchronous - what would they have had driving it?


A number of years back I implemented SDLC and BiSync in a STM32
microcontroller. I used it to connect various IBM 3270 compatible terminal
systems to the Hercules emulator.

I made a small board with a STM32 bluepill and a few level converters.
There is BISync software the interfaces with the IBM 2701 simulation in
Hercules, then there is SDLC software that connects to the IBM 3705
simulator by Henk

It is maybe not a direct fit for what you want to do but could probably
very easily be adapted.
Since it is USB it can easily be interfaced.

Browse this repo if you are interested:
https://github.com/MattisLind/alfaskop_emu/


/Mattis


>
>
> ok
> bear.
>
>

[cctalk] Re: programming the IBM PC synchronous serial boards (Northstar Advantage project)

[Ethan Dicks via cctalk]

On Fri, Dec 22, 2023 at 10:20 PM Chuck Guzis via cctalk
 wrote:
> Sync (Bisync, SDLC/HDLC) was fairly popular back in the day for linking
> with mainframes.  (Think, for example, IBM HASP).   On PCs and the like,
> the Intel 8251 was used a lot, but even the Signetics 2651 has the sync
> mode, with the ability to recognize a double-byte sync.

The COMBOARD line of Bisync and SNA protocol engines came out of the
HASPBOX product, which was 100% DEC hardware, so we started with a
COM5025 (same as at least one of DEC's sync seral boards) and we later
moved to the Zilog Z8530 (but only ever used its second port as a
local async debug port)

> The protocol for any of the above higher-level protocols is fairly
> complex and there are manuals for that

Yeah, implementing Bisync from scratch on a new platform would be
quite an effort.  There are a few poorly-documented "gotchas" to work
through/around.

-ethan

[cctalk] Re: programming the IBM PC synchronous serial boards (Northstar Advantage project)

[Chuck Guzis via cctalk]

On 12/22/23 16:02, Glen Slick via cctalk wrote:
> On Fri, Dec 22, 2023 at 2:13 PM r.stricklin via cctalk
>  wrote:
>>
>> Did IBM ever publish programming information for their PC SDLC or BiSync 
>> communications boards? I’m wondering about the possibility of programming 
>> one to drive the synchronous protocol needed for “booting” a Northstar 
>> Advantage over its serial port.
>>
> 
> Are you looking for something beyond the low level information in the
> IBM Options and Adapters reference manuals?
> 
> https://minuszerodegrees.net/oa/oa.htm
> 
> IBM Synchronous Data Link Control (SDLC) Adapter
> https://minuszerodegrees.net/oa/OA%20-%20IBM%20SDLC%20Adapter.pdf
> 
> IBM Binary Synchronous Communications (BSC) Adapter
> https://minuszerodegrees.net/oa/OA%20-%20IBM%20Binary%20Synchronous%20Communications%20Adapter.pdf

Sync (Bisync, SDLC/HDLC) was fairly popular back in the day for linking
with mainframes.  (Think, for example, IBM HASP).   On PCs and the like,
the Intel 8251 was used a lot, but even the Signetics 2651 has the sync
mode, with the ability to recognize a double-byte sync.

One key difference from async mode is that while async operates with
start and stop bits to synchronize character data, sync sends as a block
of data with no start/stop overhead.  Idle times are automatically
filled with SYN characters.

The protocol for any of the above higher-level protocols is fairly
complex and there are manuals for that.  As far as software, I may have
some for 8085/8251 kicking around.

Interestingly, I've used synchronous mode to read certain proprietary
floppy formats.  After all, the two are cousins.  You have Idle
characters, ID fields, etc.

Sync mode can be pretty efficient on a leased line.  It was pretty much
the default back in the Bell 408 days.

--Chuck

[cctalk] Re: programming the IBM PC synchronous serial boards (Northstar Advantage project)

[r.stricklin via cctalk]

> On Dec 22, 2023, at 4:02 PM, Glen Slick via cctalk  
> wrote:
> 
> On Fri, Dec 22, 2023 at 2:13 PM r.stricklin via cctalk
>  wrote:
>> 
>> Did IBM ever publish programming information for their PC SDLC or BiSync 
>> communications boards? I’m wondering about the possibility of programming 
>> one to drive the synchronous protocol needed for “booting” a Northstar 
>> Advantage over its serial port.
>> 
> 
> Are you looking for something beyond the low level information in the
> IBM Options and Adapters reference manuals?
> 

No, I guess not. I don’t know why I assumed they wouldn’t be in there.


ok
bear.

[cctalk] Re: programming the IBM PC synchronous serial boards (Northstar Advantage project)

[Glen Slick via cctalk]

On Fri, Dec 22, 2023 at 2:13 PM r.stricklin via cctalk
 wrote:
>
> Did IBM ever publish programming information for their PC SDLC or BiSync 
> communications boards? I’m wondering about the possibility of programming one 
> to drive the synchronous protocol needed for “booting” a Northstar Advantage 
> over its serial port.
>

Are you looking for something beyond the low level information in the
IBM Options and Adapters reference manuals?

https://minuszerodegrees.net/oa/oa.htm

IBM Synchronous Data Link Control (SDLC) Adapter
https://minuszerodegrees.net/oa/OA%20-%20IBM%20SDLC%20Adapter.pdf

IBM Binary Synchronous Communications (BSC) Adapter
https://minuszerodegrees.net/oa/OA%20-%20IBM%20Binary%20Synchronous%20Communications%20Adapter.pdf