I never tried soldering a QFP160, it's hard. Tips: tack the corner pins making sure it's well aligned. For the remaining pins, spread a thin layer of solder paste (mix of powdered solder and flux) over the pins/pads and work your way around the chip slowly with a fine tip. Some prefer the no-residue or the water-soluble pastes, I found however that good old rosin-based pastes give me the most consistent results (though they're a bit hard to find these days). Use extra flux liberally. For that I use liquid flux, also rosin-based.

Post a pic. The board and chip may be salvageable, but at least for the chip that won't happen without a hot air station. I have one, but don't have tips big enough for that package (biggest I've desoldered is QFP44).

I do have something exciting to test out tomorrow afternoon.

If this works it may be a WORLD FIRST. I've never attempted a breadboard project before, so it almost certainly doomed to fail...

stamasd wrote:

I never tried soldering a QFP160, it's hard. Tips: tack the corner pins making sure it's well aligned. For the remaining pins, spread a thin layer of solder paste (mix of powdered solder and flux) over the pins/pads and work your way around the chip slowly with a fine tip. Some prefer the no-residue or the water-soluble pastes, I found however that good old rosin-based pastes give me the most consistent results (though they're a bit hard to find these days). Use extra flux liberally. For that I use liquid flux, also rosin-based.

Post a pic. The board and chip may be salvageable, but at least for the chip that won't happen without a hot air station. I have one, but don't have tips big enough for that package (biggest I've desoldered is QFP44).

Yeah I ended up using WAAAY too much solder paste and it's essentially a solid stripe of solder down each side.

I'm going to clip the chip off and clean it up as best as I can.

keenerb wrote:

stamasd wrote:

I never tried soldering a QFP160, it's hard. Tips: tack the corner pins making sure it's well aligned. For the remaining pins, spread a thin layer of solder paste (mix of powdered solder and flux) over the pins/pads and work your way around the chip slowly with a fine tip. Some prefer the no-residue or the water-soluble pastes, I found however that good old rosin-based pastes give me the most consistent results (though they're a bit hard to find these days). Use extra flux liberally. For that I use liquid flux, also rosin-based.

Post a pic. The board and chip may be salvageable, but at least for the chip that won't happen without a hot air station. I have one, but don't have tips big enough for that package (biggest I've desoldered is QFP44).

Yeah I ended up using WAAAY too much solder paste and it's essentially a solid stripe of solder down each side.

I'm going to clip the chip off and clean it up as best as I can.

I would first try to use liberal amounts of desoldering braid and see if I can salvage it anyway. It should be possible if it;s not too misaligned (like less than 2/3 of a pin space)

You might be able to draw the solder off with a chisel tip by pulling back from the package along the pins all the way around.

Finally got an ISA floppy controller that works in 8bit slot thats somewhat modern 🤣! Now I have my Gotek-HxC hooked up and it works (slooooooow, omg slow). but I put some boot disks and booted dos6/dos3/drdos etc, so some minimal testing. Now I can close it up.

I figured out my VGA problem too, I think its had a bit of a hard life and the connector is a bit loose. I need to pull it and reflow the cold connector joints. I think someone wiggled the cable a bit too much in its prior home.

The guy (or girl?) that wrote the hxc floppy dos-based browser said it's theoretically possible for the hxc to act as a hard disk if someone wanted to write a driver.

it'd just be a really slow hard disk.

It'd be an interesting option for a few retro systems though

Been a little while since this topic saw any discussion.

James Pearce has developed a Tandy-compatible 8-bit sound adapter. That was the breadboard project I posted a while back, and I was never able to get it to work due to some unknown bugs that are now known bugs. After people smarter than myself identified workarounds on the PCB, I've successfully played Conquests of Camelot and Champions of Krynn on it (with EGA video).

The xi8088 bios does have one issue that kept the card from running initially; it does something with port C0 during serial port initialization and the system freezes. I had to edit the bios.asm and replace 0C0 with 0EE in the following place:

unused_reg equ 0C0h ; used for hardware detection and I/O delays

It's line 89 in my bios.asm file. Recompile and flash and you'll be good to go.

keenerb wrote:

The xi8088 bios does have one issue that kept the card from running initially; it does something with port C0 during serial port initialization and the system freezes. I had to edit the bios.asm and replace 0C0 with 0EE in the following place:

unused_reg equ 0C0h ; used for hardware detection and I/O delays

It's line 89 in my bios.asm file. Recompile and flash and you'll be good to go.

Thanks. I'll take a look and see if I can dig up some info on what the actual change is and push it to my github repository.

https://www.youtube.com/watch?v=gbRhMyHmK0Q

My xi8088 is doing a darn good impression of a Tandy 1000 with that repro sound card.

Hey BloodyCactus/Stu:

I want to "fake" the Tandy bios identifiers (machine ID byte and "TANDY" in bios string).

Apparantly Tandy sets the machine byte at FC00:0000 to "21".

Where in the xi8088 bios is the corresponding byte? I can't quite wrap my brain around the BIOS address starting at 0xF0000h and looking for a value that's at FC00:0000.

Ill cehck it tonight, should be easy to identify but doing a quick look at the code on my github,

bios.asm has these three lines

1%include	"misc.inc"
2%include	"fnt00-7F.inc"
3%include	"time2.inc"

now, fnt00-7F.inc has a setloc of 0FA6Eh, and we need FC00, if you look in time2.inc it has a setloc of 0FE6Eh which is post your address.

we need to make a new file maybe that has something like (untested)

1setloc 0FC00h
2
3tandy_id: db 0x21

also I believe the code at the end of bios.asm that has the system identification byte needs to be removed so its only 0xFF, rather than XT/JR id byte.

I can do it tonight, wrap it in a config.inc macro so you can define TANDY in config and it will make the correct changes.

Thanks, I'll look into it. Theoretically the bios identification byte is in the same location as on a generic system; I wonder if that line on bios.asm just needs to be set to 21?

nah that needs to be 0xFF instead of (FE/FD that XT/JR use). seeing FF then look for 0x21 at other location. IMO its a bad way to detect a Tandy, without actually looking in the bios for Tandy copyright strings...

my suggestion should pass the paku paku detection from deathshadow;
http://www.vcfed.org/forum/showthread.php?324 … 0418#post240418

Well the copyright strings may be something I want to consider including as well but we'll see how far this gets me.

It's not a good idea to change either string, model or system ID bytes. I've simulated that in PCem. Forcing a non PCjr/Tandy machine to be recognised as such might make the Tandy card play, but will completely screw video output as it will force Tandy video too.

Yeah but most(?) Tandy games recognized that alternate video cards might be installed and allow you to select them via command-line or setup program.

I'm not planning on imitating Tandy full-time anyway, this is just to play with.

More than that, it's intended to be a troubleshooting option while I'm tinkering with getting games to run and checking compatibility.

I have NOT tested this, so if your gonna flash this just have your backup bios handy ok? I dont think it should have problems, I just have not flashed it yet.

This has the C0 to EE register patch, Tandy ID byte at 0xFC00:0x0000, and machine byte change.

included all the bios types in the zip if you want to choose one, they all have the same options. (I always use the bios128k-xtidel-2.0.bin version)

1bios.bin                - BIOS image for use with xiflash utility
2bios128k-2.0.bin        - BIOS image for Xi 8088 - Version 2.0
3bios128k-xtide-2.0.bin  - BIOS image for Xi 8088 - Version 2.0 with XT-IDE
4bios128k-xtidel-2.0.bin - BIOS image for Xi 8088 - Version 2.0 with XT-IDE boot menu
5bios128k-1.0.bin        - BIOS image for Sergey's XT - Version 1.0
6bios128k-xtide-1.0.bin  - BIOS image for Sergey's XT - Version 1.0 with XT-IDE

I have not pushed this to my github, if it boots for you, I will push it.

OK. I'm not going to tinker with it tonight, may have a chance tomorrow.