VOGONS


TNDLPT : Tandy Sound on parallel port

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Reply 141 of 173, by Benedikt

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carlostex wrote on 2020-10-04, 17:02:

Besides Arkanoid i patched a couple more games, AAARGH and Rockford.

I'm curious about how you patches work.
Are they custom tailored to the TNDLPT or do they use the int 0c0h + TSR trick or something like that?
I'm asking because the software interrupt plus TSR variant would imply that support for further sound cards could be added without further patching.

Reply 142 of 173, by dreamblaster

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carlostex wrote on 2020-10-04, 00:13:

I've done it!!!

It was indeed what i thought it was, but i somehow missed the code. Using a debugger really helped, while i was tracing into instructions music started to play. Isolating that code and checking that subroutine on IDA. As soon as i saw the subroutine it was an eureka moment for me. Tested in dosbox and in real hardware, of course with the Serdaco TNDLPT.

I will upload the patch tomorrow. I'm tired, spent way too much time on this crapola.

congratulations !!

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Reply 143 of 173, by carlostex

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Benedikt wrote on 2020-10-04, 17:13:

I'm curious about how you patches work.
Are they custom tailored to the TNDLPT or do they use the int 0c0h + TSR trick or something like that?
I'm asking because the software interrupt plus TSR variant would imply that support for further sound cards could be added without further patching.

Patches simply make way to detour the PC Speaker code path and follow the Tandy Sound routines instead. The way this is achieved is many times replacing conditional jumps with nops or uncondiotional jumps.

An XT class machine just needs a card configured for 0C0h, but later AT machines will need a either a TNDLPT with a TSR to redirect for the LPT port or for a different port on a Tandy ISA card.

So this is just generic patching.

Reply 147 of 173, by bjwil1991

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Definitely better than the dreaded PC Speaker music for older Sierra On-Line games that supported either the PC Speaker or Tandy 3-voice. Got one myself (haven't installed yet as I ran out of Mini USB cables and power bricks).

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Reply 148 of 173, by kolderman

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bjwil1991 wrote on 2020-12-06, 10:00:

Definitely better than the dreaded PC Speaker music for older Sierra On-Line games that supported either the PC Speaker or Tandy 3-voice. Got one myself (haven't installed yet as I ran out of Mini USB cables and power bricks).

Does anyone know if the output of this plug can be fed to line-in on sound-card or is it too amplified?

Reply 149 of 173, by bjwil1991

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I believe it can. It has a volume thumb wheel that controls the output volume. Is there a way to power on the TNDLPT without a Mini USB cable? I'm out of those and my surge protector is out of space for more plugs.

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Reply 150 of 173, by kolderman

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bjwil1991 wrote on 2020-12-07, 01:31:

I believe it can. It has a volume thumb wheel that controls the output volume. Is there a way to power on the TNDLPT without a Mini USB cable? I'm out of those and my surge protector is out of space for more plugs.

I am planning on using the mobo usb port. Will that work or are they not powered enough?

Reply 151 of 173, by bjwil1991

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It will work with USB ports on a motherboard without issues. The device itself uses 5VDC for power, but make sure the 5VDC is stable.

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Reply 153 of 173, by Cowclops

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Long time lurker, first time poster. I purchased a TNDLPT from Serdaco but noticed that it didn't render the music in Maniac Mansion or Zak Mckracken quite right (the noise tracks dropped out). No fault of the TNDLPT design, it was actually because the original TI chips used in the PCJR and widely available for re-use in the TNDLPT have a glitch where the noise track shift register gets cleared out and Lucasarts never really targeted the OG chips for their music. Instead they expected the presence of an NCR 8496 chip, which is directly used in SX/EX/probably all the *X tandy 1000s, and implemented inside the PSSJ chip of the RL/SL/TL/etc later Tandys. So I was a man on a mission - was it even possible to get an NCR 8496 chip? The spec sheets show that it was a drop in replacement for the original TI chip even though it had some slightly different behavior, so I assumed if I could get it I could just swap and test.

Sure enough, there was exactly one listing for a real NCR 8496 chip on ebay, which I purchased and just acquired today. And sure enough, I dropped that into the TNDLPT's sound chip socket and fired it up on my old Magnavox 386 to test. And it sounded perfect! I made a youtube video to show it off and Serge from Serdaco asked me to post it here, so here you go.

https://youtu.be/Lr9fHT4JeAk

Reply 154 of 173, by kolderman

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Cowclops wrote on 2021-03-18, 02:34:

Long time lurker, first time poster. I purchased a TNDLPT from Serdaco but noticed that it didn't render the music in Maniac Mansion or Zak Mckracken quite right (the noise tracks dropped out). No fault of the TNDLPT design, it was actually because the original TI chips used in the PCJR and widely available for re-use in the TNDLPT have a glitch where the noise track shift register gets cleared out and Lucasarts never really targeted the OG chips for their music. Instead they expected the presence of an NCR 8496 chip, which is directly used in SX/EX/probably all the *X tandy 1000s, and implemented inside the PSSJ chip of the RL/SL/TL/etc later Tandys. So I was a man on a mission - was it even possible to get an NCR 8496 chip? The spec sheets show that it was a drop in replacement for the original TI chip even though it had some slightly different behavior, so I assumed if I could get it I could just swap and test.

Sure enough, there was exactly one listing for a real NCR 8496 chip on ebay, which I purchased and just acquired today. And sure enough, I dropped that into the TNDLPT's sound chip socket and fired it up on my old Magnavox 386 to test. And it sounded perfect! I made a youtube video to show it off and Serge from Serdaco asked me to post it here, so here you go.

https://youtu.be/Lr9fHT4JeAk

Cool. I have a tndlpt and wasn't aware the main chip was swappable. What would i search for to find that chip on ebay etc?

Reply 155 of 173, by Cowclops

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NCR 8496 is what you're looking for, but I'm not happy to admit that the one I bought was the only one for sale on ebay. More power to you if you can find it. The chip should be found in SX/EX/TX tandies but I read that its possible for an SX to have EITHER the more common TI or less common NCR chip. Since newer tandys have a PSSJ chip, its compatible but not swappable so those won't help you either. It may be possible to buy in bulk from random electronics web sites but I don't even know where to start on an order like that.

Reply 156 of 173, by kolderman

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Cowclops wrote on 2021-03-18, 02:46:

NCR 8496 is what you're looking for, but I'm not happy to admit that the one I bought was the only one for sale on ebay. More power to you if you can find it. The chip should be found in SX/EX/TX tandies but I read that its possible for an SX to have EITHER the more common TI or less common NCR chip. Since newer tandys have a PSSJ chip, its compatible but not swappable so those won't help you either. It may be possible to buy in bulk from random electronics web sites but I don't even know where to start on an order like that.

I'll save a search and if it pops up one day I might get it 😀

Reply 157 of 173, by root42

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kolderman wrote on 2021-03-18, 03:17:
Cowclops wrote on 2021-03-18, 02:46:

NCR 8496 is what you're looking for, but I'm not happy to admit that the one I bought was the only one for sale on ebay. More power to you if you can find it. The chip should be found in SX/EX/TX tandies but I read that its possible for an SX to have EITHER the more common TI or less common NCR chip. Since newer tandys have a PSSJ chip, its compatible but not swappable so those won't help you either. It may be possible to buy in bulk from random electronics web sites but I don't even know where to start on an order like that.

I'll save a search and if it pops up one day I might get it 😀

If you can acquire more than one I bet there would be a few here who would take one (I would for sure).

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Reply 158 of 173, by Benedikt

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Cowclops wrote on 2021-03-18, 02:34:

I purchased a TNDLPT from Serdaco but noticed that it didn't render the music in Maniac Mansion or Zak Mckracken quite right (the noise tracks dropped out). No fault of the TNDLPT design, it was actually because the original TI chips used in the PCJR and widely available for re-use in the TNDLPT have a glitch where the noise track shift register gets cleared out and Lucasarts never really targeted the OG chips for their music.

That leaves me wondering...
Can the pathological case in which the LFSR becomes zero be detected and compensated for in software?

Reply 159 of 173, by lihinian

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Can anyone help me out? I am having some trouble with getting larry 1 [1987] to work on my TNDLPT.
I tried every single version I could find with both AGIT2915 and AGIT2917 patches.
As far as I know, there are only 2 versions released; one hangs on dos, and the other gives a blue screen.

I got almost everything I want working, but this one just puzzles me.
Most of the time I can get by just trying different versions from a Total Dos Collection/Exo pack. or switching around some tandy.drv files. But this one seems stubborn, am I missing something?

Any help or some pointers would be greatly appreciated.