HP 71B Ports

[Dave Frederickson]

How many front-port modules can be plugged into the 71B at once? After 30+ years I thought I knew my 71B, but was surprised to learn that the answer is FIVE.

[J-F Garnier]

Hi Dave, You're right, I just tried right now and it works. I never thought about this possibility before, and honestly it has little interest for me, for an obvious reason :-).

I tried to go further with SIX modules, but it can not work (machine lock and Memory Lost).

J-F

[rprosperi]

(06-11-2016 07:38 AM)J-F Garnier Wrote:  Hi Dave, You're right, I just tried right now and it works. I never thought about this possibility before, and honestly it has little interest for me, for an obvious reason :-).

I tried to go further with SIX modules, but it can not work (machine lock and Memory Lost).

J-F

You beat me! I planned to test this today... It's all about timing

[Sylvain Cote]

(06-11-2016 07:38 AM)J-F Garnier Wrote:  I tried to go further with SIX modules, but it can not work (machine lock and Memory Lost).

Bonjour Jean-François,

I had the same idea: HP-71B + 4 front port modules + HP-IL Dual Adapter + 2 front port modules (no card reader module inserted)
It seems that I was too persistent and I was rewarded with multiple lockup to the point that one of my 71B is currently dead.
Batteries removal, battery pins shorted, pressing ON, pressing ON and /, nothing works.
It now sits on the desk without batteries to be tested later this week.

Sylvain

[Dave Frederickson]

Before this goes any further I'd like to thank Valentin Albillo for mentioning this little curiosity in Long Live the HP-71B! .

When only one module is plugged into the dual HP-IL adapter I presume it works fine. When two HP-IL modules are plugged in, what does SHOWPORT report as being plugged into Port .05?

Its funny, I've configured all sorts of modules in Port 0 with Emu71 but had never thought of trying it with a physical 71.

Dave

[Sylvain Cote]

(06-11-2016 02:24 PM)Dave Frederickson Wrote:  When only one module is plugged into the dual HP-IL adapter I presume it works fine. When two HP-IL modules are plugged in, what does SHOWPORT report as being plugged into Port .05?

Never was able to power up the unit long enough to get that information.

(06-11-2016 02:24 PM)Dave Frederickson Wrote:  Its funny, I've configured all sorts of modules in Port 5 with Emu71 but had never thought of trying it with a physical 71.

It seems that I am old school because I frequently use the physical 71B before using the virtual 71B.
Partly because I take some time to start a Windows VM and also because I have all the physical accessories near me crying to be used.

Sylvain

[J-F Garnier]

Yes, I also tried the dual HP-IL adapter without thinking about it. But it can't work: standard front port module don't provide the configuration daisy out line, so the configuration of the 2nd module inside the HP-IL adapter is not done correctly (contrary to the HP-IL modules that *do* provide the configuration out daisy line - the multiple HP-IL adapter was considered at HP-IL module design).

A bad configuration can lead to a severe HP71 lock-up as you are experimenting. In the past I got a few of these severe lock-ups, that can be difficult to recover, even by battery removal for several hours.
My way to recover is: remove all modules, remove battery, *short-circuit* the HP71 power lines not at battery terminals because there is a diode in between, but at the card read port connector (the first and last pins).
Several attempts may be needed to recover. Each time you insert the batteries without success, you have to restart the process.

J-F

[Sylvain Cote]

(06-11-2016 02:44 PM)J-F Garnier Wrote:  My way to recover is: remove all modules, remove battery, *short-circuit* the HP71 power lines not at battery terminals because there is a diode in between, but at the card read port connector (the first and last pins).

Merci Jean-François,

The card reader *short-circuit* trick worked the first time, the unit is back online

Sylvain

[J-F Garnier]

(06-11-2016 02:24 PM)Dave Frederickson Wrote:  When only one module is plugged into the dual HP-IL adapter I presume it works fine.

Yes, it works with one module in position 1 (lower position).
It could also work (I didn't test) with a HP-IL module in position 1 and a front port module in position 2.

Quote:When two HP-IL modules are plugged in, what does SHOWPORT report as being plugged into Port .05?

SHOW PORT will report the two HPIL ROMs in ports 0.05 and 0.07. The two holes 0.04 and 0.06 are used by the HP-IL mailboxes.

Quote:Its funny, I've configured all sorts of modules in Port 5 with Emu71 but had never thought of trying it with a physical 71.

A hardly known feature of the HP71 configuration code is that it manages ports 0 to *7*, even if ports 6 and 7 are not existent in the physical machine. So, since a long time, it is possible to configure modules in ports 6 and 7 in Emu71/DOS :-)

[rprosperi]

(06-11-2016 03:16 PM)J-F Garnier Wrote:  A hardly known feature of the HP71 configuration code is that it manages ports 0 to *7*, even if ports 6 and 7 are not existent in the physical machine. So, since a long time, it is possible to configure modules in ports 6 and 7 in Emu71/DOS :-)

I am certain I have read this in the EMU71/DOS manual in the past, but until being discussed in-context like this thread, some of these details just don't register. As I told Dave, I have definitely read Valentin's article more than once, yet missed his note about the HP-IL port.

Seems both need to be read again...

Very much like the Titan File articles Joe Horn republished last year (here). I have read them all many times over the years, but re-reading them provided many new previously unknown ( = forgotten) tips and techniques.

[Christoph Giesselink]

Interesting discussion. I never thought about that I implemented all virtual modules inside Emu71/Win with DAISYIN and DAISYOUT line so that you could put them together in one single "Port".

Interesting also that Emu71/Dos supports the ports 6 and 7 which are accessed by the OS. So a quick look, if Emu71/Win could also simulate the ports 6 and 7. Main question is, could the Emu71/Win document format can handle more than 6 external ports?

Yes, it's possible, but no need.

Emu71/Win until v0.09 was only able to handle 8 logic modules (one HPIL consists of 2 modules in this count) per port. This limitation has gone with v0.10 (first published version was v1.00). So the number of external modules is only limited by the address space of the Saturn CPU.

Minor detail, looking inside the Emu71/Win v1.08beta6 source code I found a bug in the UNCNFG opcode implementation. Modules in Port 1-5 cannot be unconfigured because the un-configuration routine check if the DAISYIN line is high; this is rubbish. But also never seen, that this bug occured, because I never seen that a single module in a port was unconfigured by the UNCNFG opcode.

Any example?

[J-F Garnier]

(06-13-2016 05:56 PM)Christoph Giesselink Wrote:  Minor detail, looking inside the Emu71/Win v1.08beta6 source code I found a bug in the UNCNFG opcode implementation. Modules in Port 1-5 cannot be unconfigured because the un-configuration routine check if the DAISYIN line is high; this is rubbish. But also never seen, that this bug occured, because I never seen that a single module in a port was unconfigured by the UNCNFG opcode.

Any example?

The UNCNFG is used in the configuration code (at 10354, 106F2) to re-configure a single device (to move it at a different address). In this case, the root daisy line of that device chain is probably high, but I agree that the UNCNFG should not depend on the daisy line.
I don't know any other use of the UNCNFG opcode.

J-F