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Tandy 1000 TL/3 and Xircom PE3 Parallel Port Ethernet adapter

jasa1063

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I recently got a Tandy 1000 TL/3. I have seen previous threads about the Xircom Parallel Port Ethernet adapter not working with the TL/3 even though it has a DB25 connector and Bidirectional port capability. I have tested it on my TL/3 and have gotten the same result that the adapter is not detected. Does anyone know if there is a workaround or fix for this that has been found?
 

jasa1063

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Did you go into the Tandy setup program and make sure the parallel port bidirectional mode is enabled? You may need to run 1000TL3.EXE with the /A switch for Advanced options:

www.oldskool.org/guides/tvdog/setups.html
Yes, I have tried both the output only and bidirectional mode with no luck. I also made sure to use the AC power adapter and not the PS/2 adapter for powering it. I also tried a 2nd Xircom adapter I had and got the same result. They both work on other computers.
 

ross.dykes

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I think the Xircom is supposed to operate in nibble mode, or at least that's what I seem to remember back in the day. The Tandy parallel ports seem to be missing some signals (select input for example) that cause issues with things running in nibble mode, but the TL/3 is supposed to have that run out to the connector. Maybe validate there aren't any jumpers that need to be set to run all the signals out to the connector, and then probe out all the status lines to make sure they make it back to the chipset?
 

jasa1063

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I think the Xircom is supposed to operate in nibble mode, or at least that's what I seem to remember back in the day. The Tandy parallel ports seem to be missing some signals (select input for example) that cause issues with things running in nibble mode, but the TL/3 is supposed to have that run out to the connector. Maybe validate there aren't any jumpers that need to be set to run all the signals out to the connector, and then probe out all the status lines to make sure they make it back to the chipset?
Have a look at this post from 2016 which seems to confirm it is not compatible. That is why I was wondering if a workaround had been found.

 

ross.dykes

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I haven't heard of any, no. But do you have a logic analyzer handy? I think the next step would be to probe the handshaking on a working system and then compare it to the TL/3. I'll bet it's trying to work in nibble mode and is missing some signal.

Actually, did you try it in standard mode rather than bi-directional?


- R
 

Cloudschatze

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I spent a significant amount of time looking into this with my own TL/3. I'd validated that the necessary lines are present out to the DB25 connector, but some issue yet prevents whatever check the Xircom software does from "seeing" the adapter. Logic-level probing, or disassembly of the relevant Xircom software routines might be appropriate next-steps.

It's worth noting that the specific PSSJ used in the TL/3 wasn't used in any other system. It wouldn't be unreasonable to think there might be a bug or fault in that version of the chip.

For my part, I'd lost interest in pursuing the issue further. Where I can just pull the CF card for large data transfers, and where I have a "PiModem" connected to the serial port for all internet-related connectivity besides, using the Xircom adapter would have been superfluous.


Did you go into the Tandy setup program and make sure the parallel port bidirectional mode is enabled? You may need to run 1000TL3.EXE with the /A switch for Advanced options:

www.oldskool.org/guides/tvdog/setups.html
The setup programs for the TL/3 and RLX systems behave slightly differently than those of the earlier systems. Rather than provide command-line switches, key combinations are used from within the utility instead.

This isn't documented anywhere that I'm aware of, so, for the sake of posterity:

Code:
SETUPTL3
--------
Alt-u    BIOS/ROM DOS Setup
Alt-a    Advanced BIOS/ROM DOS Setup
Alt-b    EEPROM Registers
Alt-s    Update/Save Setup Information

I'll mention that the "Input Clock" setting under the Advanced setup page just configures additional I/O cycle wait-states, via corresponding modifications to bits 2 and 3 of EEPROM word 14. The implication here is that swapping the stock 40MHz crystal and 10MHz 286 for a 64MHz crystal and 16MHz 286, and then selecting the "Reserved" setting, would remain a supported configuration.

Code:
8MHz        Port FFEC: 82h, EEPROM Word 14, bits 2 - 3: 00
10MHz       Port FFEC: 86h, EEPROM Word 14, bits 2 - 3: 01
12MHz       Port FFEC: 8Ah, EEPROM Word 14, bits 2 - 3: 10
Reserved    Port FFEC: 8Eh, EEPROM Word 14, bits 2 - 3: 11

Outside of using the advanced setup options, or modifying the relevant EEPROM bits directly, the various wait-states can also be set on-the-fly via relevant writes to port FFEC, as referenced above. Most of the Tandy systems that I've worked with noticeably benefit from a zero wait-state configuration (80h).


Code:
SETUPRLX (both versions)
------------------------
Alt-u    BIOS/ROM DOS Setup
Alt-b    EEPROM Registers
Alt-s    Update/Save Setup Information

There's no "Advanced" screen in the RLX setup utilities, but the applicable EEPROM bits can still be changed. Here's a partial mapping concerning enabling/disabling some of the built-in peripherals:

Code:
Word 13, Bit 8 - Hard Disk Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit 9 - Parallel Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit A - Video Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit B - Floppy Disk Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit C - Serial Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit F - Parallel Port Mode - Enhanced: 0, Normal: 1

And no, in case anyone wonders, disabling the onboard XTA interface via that relevant bit still doesn't allow an RLX-B to initialize properly with the XTIDE Universal BIOS, sans XTA drive.
 

Eudimorphodon

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For my part, I'd lost interest in pursuing the issue further. Where I can just pull the CF card for large data transfers, and where I have a "PiModem" connected to the serial port for all internet-related connectivity besides, using the Xircom adapter would have been superfluous.

FWIW, if you keep an eye out there are still reasonably cheap ISA LAN cards out there to be found, and a fair number of 16 bit cards will work in an 8 bit slot. Cards based on the RTL8019 are a cheap and cheerful choice, for instance.
 

jasa1063

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FWIW, if you keep an eye out there are still reasonably cheap ISA LAN cards out there to be found, and a fair number of 16 bit cards will work in an 8 bit slot. Cards based on the RTL8019 are a cheap and cheerful choice, for instance.
I actually had a 3Com 3C509B NIC in the my TL/3, but I swapped it out for Adlib card. That is why I wanted to use the Xircom adapter. The Adlib sound card is much more useful than the NIC, at least in my case.
 

jasa1063

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Messages
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I spent a significant amount of time looking into this with my own TL/3. I'd validated that the necessary lines are present out to the DB25 connector, but some issue yet prevents whatever check the Xircom software does from "seeing" the adapter. Logic-level probing, or disassembly of the relevant Xircom software routines might be appropriate next-steps.

It's worth noting that the specific PSSJ used in the TL/3 wasn't used in any other system. It wouldn't be unreasonable to think there might be a bug or fault in that version of the chip.

For my part, I'd lost interest in pursuing the issue further. Where I can just pull the CF card for large data transfers, and where I have a "PiModem" connected to the serial port for all internet-related connectivity besides, using the Xircom adapter would have been superfluous.



The setup programs for the TL/3 and RLX systems behave slightly differently than those of the earlier systems. Rather than provide command-line switches, key combinations are used from within the utility instead.

This isn't documented anywhere that I'm aware of, so, for the sake of posterity:

Code:
SETUPTL3
--------
Alt-u    BIOS/ROM DOS Setup
Alt-a    Advanced BIOS/ROM DOS Setup
Alt-b    EEPROM Registers
Alt-s    Update/Save Setup Information

I'll mention that the "Input Clock" setting under the Advanced setup page just configures additional I/O cycle wait-states, via corresponding modifications to bits 2 and 3 of EEPROM word 14. The implication here is that swapping the stock 40MHz crystal and 10MHz 286 for a 64MHz crystal and 16MHz 286, and then selecting the "Reserved" setting, would remain a supported configuration.

Code:
8MHz        Port FFEC: 82h, EEPROM Word 14, bits 2 - 3: 00
10MHz       Port FFEC: 86h, EEPROM Word 14, bits 2 - 3: 01
12MHz       Port FFEC: 8Ah, EEPROM Word 14, bits 2 - 3: 10
Reserved    Port FFEC: 8Eh, EEPROM Word 14, bits 2 - 3: 11

Outside of using the advanced setup options, or modifying the relevant EEPROM bits directly, the various wait-states can also be set on-the-fly via relevant writes to port FFEC, as referenced above. Most of the Tandy systems that I've worked with noticeably benefit from a zero wait-state configuration (80h).


Code:
SETUPRLX (both versions)
------------------------
Alt-u    BIOS/ROM DOS Setup
Alt-b    EEPROM Registers
Alt-s    Update/Save Setup Information

There's no "Advanced" screen in the RLX setup utilities, but the applicable EEPROM bits can still be changed. Here's a partial mapping concerning enabling/disabling some of the built-in peripherals:

Code:
Word 13, Bit 8 - Hard Disk Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit 9 - Parallel Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit A - Video Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit B - Floppy Disk Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit C - Serial Port Chip Select - Disabled: 0, Enabled: 1
Word 13, Bit F - Parallel Port Mode - Enhanced: 0, Normal: 1

And no, in case anyone wonders, disabling the onboard XTA interface via that relevant bit still doesn't allow an RLX-B to initialize properly with the XTIDE Universal BIOS, sans XTA drive.
Thanks for this information on the TL/3 setup program. I was wondering how to access the advanced features. This is really good information to have!
 

vwestlife

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Messages
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Location
central NJ
Perhaps relevant is that I couldn't get a Backpack-style parallel port floppy drive to work with my 1000RL even after performing the modification to connect the select pin to the parallel port, but it worked fine with my 1000RLX. So maybe in the RLX and TL/3 Tandy changed something that fixed compatibility with some parallel port devices, but broke compatibility with others?

 

Cloudschatze

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Messages
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Location
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Perhaps relevant is that I couldn't get a Backpack-style parallel port floppy drive to work with my 1000RL even after performing the modification to connect the select pin to the parallel port, but it worked fine with my 1000RLX. So maybe in the RLX and TL/3 Tandy changed something that fixed compatibility with some parallel port devices, but broke compatibility with others?
The RL jumper modification connects the Select Input (status) line from pin 13 of the DB25 connector to the PSSJ, but, as with the TL(/2) and SL(/2) systems, there's the yet-remaining issue of the "Select-Printer" (control) line being completely omitted in the 68-pin PSSJ implementations, as applies to the RL. Presumably, the backpack drive or its software requires that signal?

The TL/3 and RLX implementations use the later, 80-pin PSSJ chips, with all parallel-port lines present and connected. Where the Xircom devices should be usable with the TL/3, but aren't, suggests some other, yet-to-be-determined difference. I don't believe I have the necessary equipment to troubleshoot the issue further, but would be happy to try any suggestions.
 

ross.dykes

Member
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Feb 25, 2020
Messages
26
Location
San Francisco, CA
So this is what I use for troubleshooting old, slow crap (which is all I can wrap my brain around anyway! =). It's still $400, but that's cheap for a logic analyzer!


It's proven to be reasonably useful when snooping on the ISA bus or a parallel port, it's not that fast but it can usually capture enough to be helpful. I sadly do not have a TL/3 to test on though. =(
 
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