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New Tandy 1000 (SX) user with problems

aitotat

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I've wanted a PC/XT for a while now (my first computer was a XT-clone with 8MHz V20, CGA, 640K and 20MB). I decided to get a Tandy 1000 to get better sound from Sierra's AGI games. I wanted a 8088 processor (so I can upgrade to V20 that my first computer had) so I thought that the Tandy 1000 SX was the best model for me. I have some questions and I hope that someone can help me.

First issue is with Sound Blaster 1.5 (CT-1320C with CMS add on). Digital playback does not work when jumpered to port 220h. Playback starts but soon everything freezes. Sound Blaster is jumpered to use IRQ7 (SW4 is turned off on motherboard) but I also tried IRQ 3 and 5 but it did not help. Port 240h works just fine. Does something on Tandy use port 220h? I know that the Sound Blaster is working since I removed it from my 286. I'd like to use port 220h if possible.

Second question is about Tandy 1000 SX power supply. I have to use a step down converter since Tandy uses 120V and does not have 120/240V switch. I noticed that inside a power supply there is a gray wire connected to pin named 120V. Close to it is another pin named 240V. Can I use the Tandy without step down converter if I remove the gray wire from 120V pin and connect it to 240V pin? I didn't want to try it since bad things could happen.

Fan on the power supply was very noisy (bad bearings). I replaced the fan with something little more effective and it was a lot quieter. Air coming out of Tandy was not even warm so I used a Zalman Fanmate to slow down the fan and now it is almost completely silent. Now the air coming out is only a bit warm when Tandy has been on for about 3 hours. Is safe to assume that everything will work fine and safe? If so, then I think I should do similar thing to my 286 and 486.

I was going to install a Plus Hardcard 40 to Tandy but it did not fit. I tested the hardcard on my 286 and it worked fine. I then removed the metal frame from the hardcard and tried to bend it so that hardcard could be installed to Tandy. I was able to get it inside Tandy only to discover that hardcard does not work anymore. Controller card seemed to work since an error was displayed after a while. Hardcard did not work even on a 286 anymore so this is not a Tandy issue. I think that some of the small wires might have loosened on the harddisk side of the hardcard. Has anyone ever tried to take to take apart hardcard like that? I'm asking that is is possible to get the connectors visible without completely breaking the harddisk part of the hardcard?


Last questions are not Tandy related but I hope it doesn't matter. It about CF-to-IDE adapters. I recently bought one for my 286. I have four Apacer cards (basic 64MB, Photo Steno 256MB, Photo Steno Pro II 256MB and Photo Steno III 512MB). 512MB card does not work. I think it uses 2048 byte sectors (it reports 238 cylinders, 16 heads and 63 sectors per track). Are there any 512MB cards that would use 512 byte sectors so that it could be used on a 286? Would the card using 2kB sectors work on a newer computer, like on my 486 that supports large drives?

What brand of CF cards do you recommend to be used as a hard disk replacements for old computers?
 

Great Hierophant

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I've wanted a PC/XT for a while now (my first computer was a XT-clone with 8MHz V20, CGA, 640K and 20MB). I decided to get a Tandy 1000 to get better sound from Sierra's AGI games. I wanted a 8088 processor (so I can upgrade to V20 that my first computer had) so I thought that the Tandy 1000 SX was the best model for me. I have some questions and I hope that someone can help me.

First issue is with Sound Blaster 1.5 (CT-1320C with CMS add on). Digital playback does not work when jumpered to port 220h. Playback starts but soon everything freezes. Sound Blaster is jumpered to use IRQ7 (SW4 is turned off on motherboard) but I also tried IRQ 3 and 5 but it did not help. Port 240h works just fine. Does something on Tandy use port 220h? I know that the Sound Blaster is working since I removed it from my 286. I'd like to use port 220h if possible.

I had no problem using my CT-1320C w/CMS in my Tandy 1000 SX at I/O 220, I7, D1. The Tandy does not use the ports at 220-22F.

Second question is about Tandy 1000 SX power supply. I have to use a step down converter since Tandy uses 120V and does not have 120/240V switch. I noticed that inside a power supply there is a gray wire connected to pin named 120V. Close to it is another pin named 240V. Can I use the Tandy without step down converter if I remove the gray wire from 120V pin and connect it to 240V pin? I didn't want to try it since bad things could happen.

The Tandy schematics show a jumper for 120/240 operation, so this wire may be the equilavent of a switch. If you want to try the power supply without risking the system, plug something in it like a hard drive or a floppy drive only. If they show signs of life, you should be safe.

Fan on the power supply was very noisy (bad bearings). I replaced the fan with something little more effective and it was a lot quieter. Air coming out of Tandy was not even warm so I used a Zalman Fanmate to slow down the fan and now it is almost completely silent. Now the air coming out is only a bit warm when Tandy has been on for about 3 hours. Is safe to assume that everything will work fine and safe? If so, then I think I should do similar thing to my 286 and 486.

The early PCs used the fans to cool the power supplies. If the area in the power supply feels temperate, you should be good.

Last questions are not Tandy related but I hope it doesn't matter. It about CF-to-IDE adapters. I recently bought one for my 286. I have four Apacer cards (basic 64MB, Photo Steno 256MB, Photo Steno Pro II 256MB and Photo Steno III 512MB). 512MB card does not work. I think it uses 2048 byte sectors (it reports 238 cylinders, 16 heads and 63 sectors per track). Are there any 512MB cards that would use 512 byte sectors so that it could be used on a 286? Would the card using 2kB sectors work on a newer computer, like on my 486 that supports large drives?

CF cards are unlikely to use 2048 bytes per sector unless they were emulating a CD. You may be talking about a cluster size of 2048 bytes or four sectors. This is not standard, the cluster size for a 512MB volume should be 16,384 bytes or 32 sectors. Try reformatting it with FAT16 of DOS 5.0 or later. I have had no problem using SanDisk's CF products.
 

aitotat

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I tried Sound Blaster 2.0 (CT1350B) and it works when set to A220, I7, D1. Maybe this has something to do with DSP version. My Sound Blaster 1.5 has DSP v1.05 and Sound Blaster 2.0 has DSP v2.01. What is the DSP version on your SB 1.5? If it is other than v1.05 then this must be a DSP related issue.

I'll put SB 1.5 back to 286 and use SB 2.0 on Tandy. Too bad that I don't have CMS chips for SB 2.0.
 

Agent Orange

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Hi Guys - Let add some of this to the mix. I have a 8-bit MediaVison (c) 1991
dual channel sound card w/thumb wheel volume adjustment (on the card itself). I've had a 1000SX since day one (Christmas '86). This card worked right out of the box. If you run the FCC - ID (IXW650-0007) you'll come up with a Micosoft link for sound card setup. On this particular card, there is a 6position DIP switch which you can seclect ADC-JOY-FM-AD2-AD1-AD0. I would suggest that you go over the card and make sure the address is set up correct. I don't think that you will need to play with IRQ's. What I would like to find is the long lost 5 1/4" setup disk. Also, if you have a copy MS-DOS 6.2(2), use the MSD.EXE utility to look at your setup.

Good luck!
 

aitotat

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I tried the 512 MB Apacer CF card on a 486. It works and BIOS identifies it to have 1006 cylinders, 16 heads and 63 sectors per track (or 503/32/63 in LBA mode). CHS 1006/16/63 means that it should work on BIOSes with 500MB limit. It just doesn't work on my 286. Maybe the BIOS is too old to initialize the card properly.

I have another Tandy issue. Why can't I hear Tandy sounds from some games before starting another game? For example I have to first start any Sierra game to be able to hear Tandy sounds from Maniac Mansion.

I have speakers connected to RCA output. I have disconnected the internal speaker inside Tandy (it was too loud). All standard PC-Speaker sounds always plays fine. It is only the Tandy sounds that won't work on some games after boot.
 

Fallo

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I have another Tandy issue. Why can't I hear Tandy sounds from some games before starting another game? For example I have to first start any Sierra game to be able to hear Tandy sounds from Maniac Mansion.

I'm not sure. You could try typing MANIAC T to start the game in Tandy mode rather than autodetecting it.
 

Great Hierophant

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I have another Tandy issue. Why can't I hear Tandy sounds from some games before starting another game? For example I have to first start any Sierra game to be able to hear Tandy sounds from Maniac Mansion.

I have speakers connected to RCA output. I have disconnected the internal speaker inside Tandy (it was too loud). All standard PC-Speaker sounds always plays fine. It is only the Tandy sounds that won't work on some games after boot.

I'm not sure. You could try typing MANIAC T to start the game in Tandy mode rather than autodetecting it.

The early Tandys have an audio switch chip that directs all sound generation to either the internal PC speaker or the RCA audio output. The programmer can set in software which will receive the audio generated from the Tandy (both "PC Speaker" and 3-voice). In the SX, the default is that the internal speaker will be used. The Sierra games set it so that the RCA audio output is also used, which Maniac Mansion fails to do. With Sierra games, the music will be heard from both the internal speaker and the RCA audio jack. There is another setting to turn off the internal speaker. In short, you have to use the method you described to get RCA from Maniac Mansion or program the 8255.
 

aitotat

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Good to know. Maybe i should investigate things before disconnecting any wires.

I received NEC V20 today. I haven't installed it yet since i want to do some benchmarking with 8088 first. Does anyone know good benchmarking programs? I'd like to test CPU, memory and video speeds and compare them to V20.
 

Agent Orange

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Good to know. Maybe i should investigate things before disconnecting any wires.

I received NEC V20 today. I haven't installed it yet since i want to do some benchmarking with 8088 first. Does anyone know good benchmarking programs? I'd like to test CPU, memory and video speeds and compare them to V20.
I don't know what the bench marks are, but my 1000SX with the V20 blows that 8088 out of the water. I upgraded mine when it was new, back in '87, and its been up and running ever since. Have you maxed out your RAM out to 640KB? If not, very worth while upgrade. I do have some benchmark programs somewhere - I'll see what I can do. Bottom line is you won't miss your old chip
 

Fallo

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The early Tandys have an audio switch chip that directs all sound generation to either the internal PC speaker or the RCA audio output. The programmer can set in software which will receive the audio generated from the Tandy (both "PC Speaker" and 3-voice). In the SX, the default is that the internal speaker will be used. The Sierra games set it so that the RCA audio output is also used, which Maniac Mansion fails to do. With Sierra games, the music will be heard from both the internal speaker and the RCA audio jack. There is another setting to turn off the internal speaker. In short, you have to use the method you described to get RCA from Maniac Mansion or program the 8255.

Alright. So after running Sierra games, the Tandy will be set to output sound through the RCA jack and presumably it will stay that way until you reprogram it or reboot the computer. By comparison, the PCjr only outputs 3-voice sound through the RCA output.

I received NEC V20 today. I haven't installed it yet since i want to do some benchmarking with 8088 first. Does anyone know good benchmarking programs? I'd like to test CPU, memory and video speeds and compare them to V20.

The 1000 SX uses an 8086. You would need to put an NEC V30 and not a V20 in it.
 

Agent Orange

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Alright. So after running Sierra games, the Tandy will be set to output sound through the RCA jack and presumably it will stay that way until you reprogram it or reboot the computer. By comparison, the PCjr only outputs 3-voice sound through the RCA output.



The 1000 SX uses an 8086. You would need to put an NEC V30 and not a V20 in it.
No sir. My 1000SX had a 8088 and is now running a NEC V20. The next bump, I believe, was the TL - and it had a 80286 on a 8-bit bus.
 

Great Hierophant

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Alright. So after running Sierra games, the Tandy will be set to output sound through the RCA jack and presumably it will stay that way until you reprogram it or reboot the computer. By comparison, the PCjr only outputs 3-voice sound through the RCA output.



The 1000 SX uses an 8086. You would need to put an NEC V30 and not a V20 in it.

No sir. My 1000SX had a 8088 and is now running a NEC V20. The next bump, I believe, was the TL - and it had a 80286 on a 8-bit bus.


I think he was confusing it with the 1000 SL. You can output the PC Speaker/Beeper output to the RCA jack on the PCJr., you need to program the audio multiplexer to do so. I believe the default is the 3-voice sound on the Jr. The disadvantage of the Jr. is that you can only have one source being output at a time to the RCA jack/RF Modulator, whether cassette, expansion bus, speaker or 3-voice.

On the Tandy, you can have both the Speaker and the 3-voice output to the RCA jack if you program the mixer properly. The reason why is because PC Speaker Sound is routed through the 3-voice chip on the Tandy and not on the Jr.
 

Great Hierophant

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On the EX, HX, TL,SL, SL/2, RL, RLX, RSX the internal speaker will play both the 3-voice and PC Speaker unless something is connected to the headphone jack. In that case, obviously you will get sound from the headphone jack and not the speaker. The volume control knob controls both sources of output. Rather neat for digitized sound, because the volume control can make this sound much louder.

The only Tandy 1000s with an RCA output are the 1000/A/HD, SX and TX. The TX also has a headphone jack and volume control that acts like ones on the systems listed above. According to the TX's schematic, the audio from the multiplexer goes to the RCA jack and the Internal Speaker/Headphone jack, so if you hear music from one, you will also hear sound from the other.

The Tandy 1000/A/HD and the SX have the most complex sound output circuits. The 1000/A/HD and can route PC Speaker, PC Speaker + 3-voice or I/O Bus Audio to the external RCA jack via the multiplexer. In addition, the 1000 connects the Internal Speaker to the PC Speaker + 3-voice. The Internal Speaker will always be on, but there may be an internal potentiometer to control the volume. The SX makes all sound go through the multiplexer and has an pot to control the volume of the internal speaker. The schematics show that you can obtain either PC Speaker + 3-voice or I/O Bus Audio to the Internal Speaker and PC Speaker, PC Speaker + 3-voice or I/O Bus Audio to the external RCA jack.

Code:
According to the schematics, the selectors work as follows on the SX:

I/O Port 61

Bit 5                 Bit 6  
SNDCTRL0         SNDCTRL1         Internal            External
0                     0                PC Spk + 3V      PC Spk
0                     1                Nothing             PC Spk + 3V
1                     0                Bus I/O             Bus I/O
1                     1                PC Spk + 3V      PC Spk + 3V

SNDCTRL2 turns off output to the Internal Speaker if set to 0.  

On the original 1000/A/HD, they must work like this:

I/O Port 61

Bit 5                 Bit 6                
SNDCTRL0         SNDCTRL1         External
0                     0                PC Spk
0                     1                 Nothing
1                     0                Bus I/O
1                     1                 PC Spk + 3V

SNDCTRL2 does not exist.

On the HX or TX, if SNDCTRL2 (I/O Port 61, Bit 4) is 0, then PC Spk; if 1, then PC Spk + 3V.  SNDCTRL0 or SNDCTRL1 aren't present.  Bus audio is not supported.

According to the schematics, the selectors work as follows on the EX if :

I/O Port 61

Bit 5                 Bit 6                Bit 4
SNDCTRL0         SNDCTRL1         SNDCTRL2=0     SNDCTRL2=1
0                     0                     PC Spk             PC Spk + 3V
0                     1                     Nothing             PC Spk + 3V
1                     0                     Bus I/O             Bus I/O
1                     1                     PC Spk + 3V      PC Spk + 3V

The PCjr. cannot route anything other than PC Speaker sound to its internal piezoelectric tweeter (no speaker cones here).  The Tandy 1000s route 3-voice and PC Speaker sound to their internal speakers, which can be larger than the ones in other PCs.  

I/O Port 61

Bit 5                  Bit 6
SPKR Switch 0     SPKR Switch 1     External
0                       0                      3V
0                       1                      Spk
1                       0                      Cassette In
1                       1                      Bus I/O

The default value in the SX is 0 for SNDCTRL0,1,2 and should be in all other systems except for the HX & TX, where it must be 1 in order to hear any sound.
 
Last edited:

aitotat

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I tried to change SNDCTRL bits according to the schematics that Great Hierophant posted.

SNDCTRL2 disables internal speaker when set to 1 (not when cleared to 0!). I didn't try bus I/O settings but SNDCTRL0=cleared and SNDCTRL1=set didn't work.

Here is what seems to work fine.
Both internal and external speakers enabled (default on Sierra games):
SNDCTRL0 = set
SNDCTRL1 = set
SNDCTRL2 = cleared

Internal speaker only (Tandy default, note that 1-voice PC-Speaker will always be heared from external speakers also):
SNDCTRL0 = cleared
SNDCTRL1 = cleared
SNDCTRL2 = cleared

External speaker only (disables internal speaker completely):
SNDCTRL0 = set
SNDCTRL1 = set
SNDCTRL2 = set

I wrote a small program (source codes are included). Loading it in autoexec.bat will do just what I wanted. No need to disconnect internal speaker anymore. Internal speaker stays quiet even in Sierra games.

Tandy 1000 SX definitely has a 8088. It can be seen on some of the pictures that i took from my Tandy 1000 SX.
 

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Great Hierophant

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Oops, my mistake. It also turns out that manipulating SNDCTRL 0 & 1 bits will not stop music coming from the Internal Speaker, regardless of setting. I am much obliged for the program and will try it out.
 

aitotat

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I took a look at Tandy 1000 SX Technical Reference Manual. There is a Sound Functional Block Diagram on page 26 (PDF 35). I understood that the multiplexer works the following way:

Code:
SNDCTRL
2 1 0   | Internal | External
-----------------------------
0 0 0   | 1V + 3V     | 1V        (System Default)
0 0 1   | 1V + 3V     | Ground
0 1 0   |1V+3V or Bus?| Bus?
0 1 1   | 1V + 3V     | 1V + 3V
1 0 0   | Nothing     | 1V 
1 0 1   | Nothing     | Ground
1 1 0   | Nothing     | Bus? 
1 1 1   | Nothing     | 1V + 3V

If that is the case, then i'll update my program tomorrow since it is possible to completely disable external speaker.

What does the trimmer R26A on the motherboard do? Could it be volume control for internal speaker? The internal speaker is so loud that it is almost unusable. That does not matter anymore since i can use external speakers but i still would like to turn the internal speaker volume down.
 

aitotat

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Thank you for all the help so far.

Adjusting the R26A sure helped a lot. I still had to remove internal speaker. Some very annoying sounds are coming from it. Like when typing dir, you can hear the characters appearing on the screen. Is this normal? Disabling internal speaker by software doesn't stop that annoying sound. Good thing that external speakers work fine.

I was able to modify the power supply for 240V. It was easy since that wire wasn't even soldered. I replaced the fan again. This time i used Nexus SP802512L-03 (i bought three of those, for 286 and 486 also). They are said to be quiet but they were too loud for me. I had an extra U.L.N.A. adapter from Noctua fans and that helped. Now it is very quiet.

Here is a completely rewritten Tandy 1000 SX Speaker Multiplexer v1.1.0. It now allows to disable sound completely and to reset system defaults. It also allows to set SNDCTRL bits manually so it can be used with other Tandy 1000 models also. I don't know how the bits work on other models.
 

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