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Tandy 2500 SX/20 and Tandy 4825 SX restoration thread

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acadiel

Experienced Member
Joined
Dec 19, 2009
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287
Instead of posting everywhere across here (and in the AHCS's Yahoo group), I figure I can leave this as my 'here's what I'm doing to fix these two systems up' thread.

Stay tuned as I reply to this thread and ask questions as I fix these up.

Recently acquired two Tandys that they must have made right before they quit making them. I already have a Tandy 1000 from my father in law as well as a Tandy 1000 RLX that I acquired a few months back.

Tandy 2500 SX/20 -
  • 386 SX/20
  • 2MB RAM (4 x 256K 30 pin SIMMs + 1MB onboard)
  • 80MB WD IDE drive (with issues)
  • 3.5" 1.44MB and 5.25" 1.2M floppy drives.
  • Built in Tandy audio (I think)
  • Built in VGA
  • Apparently a standard PS/2 keyboard and mouse connection (unlike the RLX)
  • No software loaded. Drive was empty, but I did find it's "Setup" program.

Plans:
  • Up RAM to 5MB (max onboard) - 4 x 1M 30 pin SIMMS + 1M onboard (These are on the way from a friend)
  • Add extra video DRAM chips.
  • Repair or replace hard drive with another solution (i.e. disk on chip or Compact Flash, or XT IDE card with Compact Flash). (Trying a 256MB DOC from eBay)
  • Possibly replace 5.25" drive with IDE CDROM drive.
  • Figure out Tandy sound and/or add a ISA Soundblaster.

Tandy 4825 SX-
  • 486 SX/25
  • 5MB RAM (4 x 1M 30 pin SIMMs + 1MB onboard), 4 empty sockets
  • ?? IDE drive
  • 3.5" 1.44MB drive. 5.25" bay is empty.
  • No Built in audio
  • Built in VGA
  • Apparently a standard PS/2 keyboard and mouse connection (unlike the RLX)
  • Windows 3.x loaded. I found the 4825SX program on the net for it.

Plans:
  • Up RAM to 32MB (eight x 4MB 30 pin SIMMs).
  • Add extra video DRAM chips.
  • Repair or replace hard drive with another solution (i.e. disk on chip or Compact Flash, or XT IDE card with Compact Flash).
  • 5.25" bay with IDE CDROM drive. (I have a 40x CDRW drive I will attempt to put in here.)
  • Add 16 Bit Soundblaster (I have a SB16 Value laying around.)
  • Add Ethernet (I have an 8 Bit 3COM card laying around.)
  • Back up the stuff on the internal drive
 
Made some modifications to the Tandy 2500 SX/20:

* RAM maxxed out to 5MB
* Disk On Chip (256MB) replaces the 80MB Seagate
* Added ISA Etherlink II card with XT-IDE 8K Universal BIOS EPROM. Card set to >C800, using I/O 300h. Onboard IDE set to NONE/NONE. MSD states card is a "second 8529A" on IRQ2.
* Installed DOS 6.22 after FDISK and making partition bootable.

Otherwise, it's still stock. Unit boots with DOS 6.22 just fine.

Attempted to install Windows for Workgroups:
* Went through the installer just fine (keyboard and mouse worked).
* Selected Etherlink II, and hooked up AUI connection to TP and a switch.
* Installed successful and system rebooted just fine.

System will not get past WFW splash screen. Here's what I've tried:
* Excluding >A000-EFFF in config.sys from EMM386 and in the EMMExclude in system.ini - nada
* Booting with bootlog.txt enabled WIN /B - shows failure on NETAPI.DLL
* Booting without network WIN /N - works, but no response from keyboard and mouse at all. Unit appears locked up. Caps lock doesn't work.

Any other thoughts? Figured this would be relatively straightforward :)

Edit: Re-ran through WFW setup and selected 'no network'. Windows now starts, but still freezes at Program Manager with no keyboard/mouse input.

Edit #2: Resolved. Went to this site http://support.radioshack.com/soft_tandy.htm and downloaded a keyboard fix. Was a manual copy and edit of the system.ini.

I also installed the Tandy DAC driver and the VGA drivers from that page as well. They both work fine.

I have some 40 pin ZIP 256k x 16 chips on the way to max the RAM to 512K on the video so that I can do 640x480x256. Right now, I'm stuck at 640x480x16 or 800x600x16.

FYI, for this system, MSD told me this with just the Etherlink II installed with BOOT ROM. I went ahead and excluded C000-CB7F in both config.sys and in system.ini to avoid conflicts with these regions.

C000-C3FF - ROM
C400-C7FF - half ROM half possible (questionable)
C800-CB7F - ROM

So, for the 2500 SX/20, I am just going to add the video RAM. Going to not install the IDE CDROM, but keep the 5.25" drive just in case I need it. So, this system is now restored for the most part. :)

Tandy 2500 SX/20 -
  • 386 SX/20
  • 5MB RAM (4 x 1M 30 pin SIMMs + 1MB onboard)
  • 256MB Disk On Chip
  • 3.5" 1.44MB and 5.25" 1.2M floppy drives.
  • Built in Tandy DAC Audio
  • Built in VGA (soon to be 512K)
  • PS/2 keyboard and mouse connection
  • Etherlink II network card with XTIDE 386 Boot ROM
  • Radio Shack two port ISA Game controller card
  • DOS 6.22 and Windows for Workgroups 3.11 installed
 
Last edited:
Bump to see if anyone knows of the specs of the above VRAM expansion for the 2500 SX/20. Thanks!
 
Did some more work on the 4825.

Tandy 4825 SX-

Was:
  • 486 SX/25
  • 5MB RAM (4 x 1M 30 pin SIMMs + 1MB onboard), 4 empty sockets
  • 120MB IDE drive
  • 3.5" 1.44MB drive. 5.25" bay is empty.
  • No Built in audio
  • Built in VGA
  • Apparently a standard PS/2 keyboard and mouse connection (unlike the RLX)
  • Windows 3.x loaded. I found the 4825SX setup program on the net for it.

Now:
  • Evergreen AMD Overdrive processor (equivalent of a P100).
  • 32MB (8x 4MBx9 30 pin SIMMs) - on order, still currently at 4MB
  • Add extra video DRAM chips to bring to 1MB - 4x 256K x 4 - on order, still currently at 512K
  • 1GB Disk on Module (with help from a 40 pin male IDC to 40 pin male IDE adapter)
  • IDE CDRW drive (Lite-On, beige) in 5.25" Bay, setup with OAK CD ROM drive and MSCDEX from Win98 Boot disk, hooked audio cable to SoundBlaster 16.
  • SB16 Value added and set up (disks found on the net)
  • Etherlink III added and set up (enabled ROM, changed IRQ, etc, with DOS setup program)
  • XT-IDE 386 BIOS installed on Etherlink III
  • Windows 3.1 and MS DOS 5 still installed

Idiosyncrasies:

  1. XT-IDE BIOS makes the internal drive show up as C *and* D. Tried turning drives to NONE for primary/secondary in BIOS, no effect. Turned off the "IDE drive installed" flag (i.e. set to NO), and XT IDE won't even show its boot screen after that. Strange.
  2. Windows 3.1 won't let me move any of the icons around or clean them up. Very strange. Tried a few different menu options, and it might be something really simple.
  3. The volume on the Soundblaster won't stick across reboots.
 
I have a Tandy 2500 as well.

I did the following upgrades:

Soundblaster 16 with IDE
IDE 4x CD ROM Drive (connected to the Sound Blaster Card)
XT-IDE with front mounted Compact Flash Slot (using the spare 3.5" drive bay).
MPU-401 compatible card for MT-32 sound

Works quite well overall, but have found there are a limited set of titles that work well on a 386/20 for CD-ROM. I guess its useful for some older King's Quest titles that had CD-ROM support, and maybe games like Syndicate.
 
acadiel said:
XT-IDE BIOS makes the internal drive show up as C *and* D. Tried turning drives to NONE for primary/secondary in BIOS, no effect. Turned off the "IDE drive installed" flag (i.e. set to NO), and XT IDE won't even show its boot screen after that. Strange.
Click to expand...

Strange indeed! You didn't by any chance accidentally configure the XUB to use two controllers, both handling the same drive, did you? (I don't believe you did but I have to ask). Where is the ROM located (which segment address)? Try moving that to another segment if possible. If nothing helps then we might have to dump and disassemble the system BIOS to analyze what really happens in this weird machine. I'm sorry to say I probably won't have time to do this.

BTW, are you using a custom build (if so what build options did you use?) or just the regular 386 build?
 
Krille said:
Strange indeed! You didn't by any chance accidentally configure the XUB to use two controllers, both handling the same drive, did you? (I don't believe you did but I have to ask). Where is the ROM located (which segment address)? Try moving that to another segment if possible. If nothing helps then we might have to dump and disassemble the system BIOS to analyze what really happens in this weird machine. I'm sorry to say I probably won't have time to do this.

BTW, are you using a custom build (if so what build options did you use?) or just the regular 386 build?
Click to expand...

Nope, all I did is got the R580 build from here: https://www.lo-tech.co.uk/wiki/XTIDE_Universal_BIOS and burned it to a 2764. I have the same R580 build in the Etherlink 8 bit ISA in the Tandy 2500, and it doesn't duplicate the drives.

Used the DOS setup program for the Etherlink III to enable the onboard ROM, and I forgot what I/O it put it at (I told it to "automatic setup" everything). I can try changing that; that's a good thing to rule out. Thanks!

At least the ROM on this thing is an EPROM (it looks more like Tandy used standard-ish Phoenix BIOS chips as time went on before they bailed), and I can easily dump it and put it here if anyone wants to look at it.
 
mojorific said:
I have a Tandy 2500 as well.

I did the following upgrades:

Soundblaster 16 with IDE
IDE 4x CD ROM Drive (connected to the Sound Blaster Card)
XT-IDE with front mounted Compact Flash Slot (using the spare 3.5" drive bay).
MPU-401 compatible card for MT-32 sound

Works quite well overall, but have found there are a limited set of titles that work well on a 386/20 for CD-ROM. I guess its useful for some older King's Quest titles that had CD-ROM support, and maybe games like Syndicate.
Click to expand...

Yeah, the 2500 seems like a nice 386. I might keep it handy in case I need to transfer anything from 5.25" disk and just use the Tandy 486 for DOS gaming. :)

It's a shame the Tandy DAC is kind of non standard and only works in Windows. It'd be cool if it worked in DOS. :)
 
Final 4825 setup.

Tandy 4825 SX-

Was:
  • 486 SX/25
  • 5MB RAM (4 x 1M 30 pin SIMMs + 1MB onboard), 4 empty sockets
  • 120MB IDE drive
  • 3.5" 1.44MB drive. 5.25" bay is empty.
  • No Built in audio
  • Built in VGA
  • Apparently a standard PS/2 keyboard and mouse connection (unlike the RLX)
  • Windows 3.x loaded. I found the 4825SX setup program on the net for it.


Now a super great DOS gaming system. :)
  • Evergreen AMD Overdrive processor (equivalent of a P100).
  • 32MB (8x 4MBx9 30 pin SIMMs)
  • 1MB Video RAM upgrade
  • 8GB Disk on Module (with help from a 40 pin male IDC to 40 pin male IDE adapter), 2GB partitions (C:\, E:\, F:\, G:\)
  • IDE CDRW drive (Lite-On, beige) in 5.25" Bay, setup with OAK CD ROM drive and MSCDEX from Win98 Boot disk, hooked audio cable to SoundBlaster 16. (D:\ drive)
  • SB16 Value added and set up (disks found on the net)
  • Etherlink III added and set up (enabled ROM, changed IRQ, etc, with DOS setup program)
  • XT-IDE 386 BIOS installed on Etherlink III
  • Windows 3.1 and MS DOS 6.22 installed
 
Could you provide a little more detail about the CPU you upgraded to?

The manual of my 4825 SX says you can only upgrade to a 486DX2, were you able to get a DX4 working? Is your AMD 3V or 5V?

Thanks for the write up!
 
acadiel,

I was just wondering. Have you had any luck with the Video DRAM?

I'm looking to soup up my 2500 SX/20. I see the same 256kx16 on ebay, but not anything else.
 
drall said:
acadiel,

I was just wondering. Have you had any luck with the Video DRAM?

I'm looking to soup up my 2500 SX/20. I see the same 256kx16 on ebay, but not anything else.
Click to expand...

Nope, I haven't found any zip chips that work yet. Those things are fun to plug in as well.
 
I found a doc on the wayback machine that says that the ram is SRAM? have you found any chips that work? I'm asking for me :) It's the last upgrade needed for my Tandy 2500SX/20
 
had a goofball idea... gonna actually try to contact Tandy/radioshack(whatever they have become) and see if they can explain what the durn specs are for the video memory upgrade

:p
 
MindParadox said:
Umm, holy crap? I've been googling this stupid part number for like a week now and nothing :p thank you!
I'll post here if it works(and hey, apparently I'll have 8 of the durn things to get rid of, so if anyone needs a couple, lemme know, cheep! :p)
Click to expand...

I'm in for them to get mine upgraded. :)
 
MindParadox said:
Umm, holy crap? I've been googling this stupid part number for like a week now and nothing :p thank you!
I'll post here if it works(and hey, apparently I'll have 8 of the durn things to get rid of, so if anyone needs a couple, lemme know, cheep! :p)
Click to expand...

Did they work? I gave up on this.
 
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