exxos's Atari, Amiga & retro forum

Some further messing around with the TT, MagiC etc. and exploring the various up and down sides of the various desktop options has been most enjoyable as it's all completely new to me. File transfer from a modern machine was proving tedious with the 720K disk images in the Gotek, so I downloaded the HDDRIVER demo with the intention of using it and my SCSI2SD to copy files onto the TOS/DOS partitions it can create, unfortunately writing to these immediately resulted in failure to boot so I scrapped that idea.

I then found an article that suggested using the 2.5MB DD image option in the HXC Floppy Emulator software to create larger images, and to my surprise this worked, so I am OK for medium sized data transfer for the moment. I may explore a SCSI CD drive option in future, or maybe one of the USB network card options.

I tried to find one of the modern TT RAM expansions so I could have a play with Atari UNIX but failed, so bought a quite expensive 4MB SIPP expansion instead - this was a pain to fit as the CPU daughterboard was wedged right against the TT RAM socket but once I figured that out a bit of manipulation with a screwdriver allowed it to fit. I also had to put some card under the RAM expansion or it would have shorted on the stupid excessive shielding, but at the moment it is working:


The only Atari UNIX related installation media I could find were images of existing installs, so I downloaded "Mark's Fixed" one from http://www.atariunix.com/hdd_images/ and imaged it to an SD card using dd. The SCSI2SD worked straight off with this and booted it up (very slowly):


After messing about with it for a bit and finding it mostly unusable due to pausing when it was apparently paging to disk (also I don't think I can get the GUI working without a VGA converter to high res) I shut it down for revisiting later.

You can also see in the above pic the 4xAA battery holder I purchased for the RTC battery replacement - in restrospect i should have bought a 1x4 rather than 2x2 configuration as it doesn't fit in the original location due to being too high. This won't be an issue unless I put a real hard drive back in, which I may do at some point.

I have spent the last few weeks generally tinkering with the TT - things like Mint and UNIX (above) really need more than 4MB TT RAM and in the case of the latter, a special display adapter or monitor. I have settled on Magic for now as the best balance of usability and speed. I also bought a 4x1 AA battery holder which fits properly.

I went for the OSSC to sort the display out and after a bit of fiddling about got an acceptable picture:


It's not perfect in that some vertical lines can be seen but it's miles better than it was before, so happy enough with that. Here it is in flashy 256 colour mode displaying the most colourful thing in the world, a rainbow:


I mounted the SCSI2SD properly and fashioned a replacement LED from the parts pile which doesn't mount properly but works fine until I get a proper one. A final clean up and it looks pretty good:


I got hold of a cheap broken SCSI CD drive in external case and replaced the broken drive with one I had lying about - ExtenDOS enabled this to work with pretty much no hassle (in contrast to my Amiga 2000).

The form factor is really nice and I like the desk friendliness/semi dockable keyboard etc. Not sure what else I will be doing with this so it has gone into the cupboard for now - it could do with a quieter PSU fan as even with the redundant extra case fan disabled it's a noisy beggar.

:dualthumbup:

You can replace the fans with Noctua ones which are quiet. You just have to make sure that on the power supply that you connect the fan wires the opposite way around to what you expect as the connections are GND and -12V.

IBM PS/2 Model 90 XP

I'm not generally into old PCs but this one caught my eye as it's a bit different in a few ways: it is a 486 based PS/2, it has IBM's failed Microchannel (MCA) architecture instead of PCI, ISA etc, and has an expandable processor independently of the motherboard (the "XP" in the name - the CPU socket and important parts of the system including the MCA controller and the BIOS sit on a processor card so can be swapped for e.g. a Pentium). I spotted it had a hard-to-find MCA sound card and what looked like a CPU upgrade so I bought it - described as "dented, does not power on".

It turned up and was true to its description - it failed to power on.


I opened it up to reveal the MCA cards, miles of cabling and two hard drives in addition to the IBM floppy that uses a 34 pin cable which it takes its power from:


Here is the processor card (called a "complex" by IBM), in which you can see an Evergreen CPU upgrade containing an AMD 5x86-133:


MCA sound card:


MCA SCSI card containing some cache memory and proprietary internal and external connectors:


Original looking half height 400(!) meg hard drive which according to the sticker was made next door to a previous place of work:


Absolutely nothing came out of the PSU when powered on, so I tested the switch (OK - it's similar to ATX) then removed the PSU and had a look around. Some scorching was noted on a daughter PCB so I desoldered it to be presented with this:


What looks like a regulator had carbonised and a couple of resistors nearby had also been taken out. I cleaned it up (pic is taken post cleanup) but couldn't identify the burned parts or what caused them to end up in that state, so decided to replace the PSU with a slightly more modern ATX one. Being old it wants more amps on the 5V rail than new ones provide, so i fetched my spare 2003 era ATX PSU from the loft and ordered a breakout board for testing as I am bored of jamming loose cables into the ATX connector.

To be continued...

Did you know that the MCA connector is the same as the CD32 expansion. When I made my own CD32 expansions I sacrificed several of these

PS/2 Continued

While waiting for parts to arrive I removed everything from the case and gave it a good clean - there was a thin oily mist over everything which was especially fun to get off the motherboard. My ATX breakout board then arrived so I desoldered the custom edge connector type PSU cables from the old power supply and screwed them in to the appropriate places on the board.

The parts sans hard drives and expansion cards were all set up haphazardly on my desk and I powered it on, to be greeted with the power LED going green (good) and nothing else (bad). I then noticed I had connected the PWRGOOD cable up to the wrong place so corrected this and got a display with a flashing cursor:


The screen then went blank again with no apparent further progress, lots of checking of things then happened only to discover that this happens twice during the power on process and it then carries on, only to actually complain/confirm all is OK with beeps very late in the process. I got an error message on the screen which was related to a missing setup partition, so I plugged in the two very old hard disks and the floppy drive and tried again - to my amazement they span up and automatically went into setup as it had detected some changes (CD ROM not connected):


I ran auto setup and it booted into OS/2 Warp 3:


Only for my monitor to display a "signal out of range" message. I don't have any old VGA CRTs around so I looked up the process to reset everything back to VGA, did so and got a desktop:


The sound card worked and everything. The previous owner appears to have been a fan of multimedia CD titles as the hard drives were full of them, not much else of interest on there though. There also appears to have been a tape drive connected at some point.

You'll notice the two large riser cards with RAM installed on them, this is the system memory and it came with 48MB RAM total. Unfortunately at least one of the sticks is giving parity errors so it's currently running with a still not-too-shabby 32MB.

Next: OS upgrades, video fun, permanent PSU replacement

PS/2 - OS, Video, PSU

Having cleaned everything up and awaiting PSU parts, I put everything properly back into the case - see pic for bare motherboard pic sans CPU and RAM risers.


I ordered a standard ATX extension cable, snipped the male end off and set about soldering the PS/2s power cables to the relevant wires - this then plugged straight into the donor PSU's ATX connector so is easily replaceable if required. I soldered up the mains input, secured everything into the stock PSU casing, and everything fitted very nicely, with no indication of the impostor PSU guts within:


I then set about installing a couple of operating systems, the most appropriate seeming to be a dual boot between Windows 95 and OS/2 Warp. Windows 95 went on first and all worked pretty smoothly, annoyingly there were no Win95 drivers released for the sound card which means it uses the 3.1 set in compatibility mode. This works OK for the most part and allows adlib support in games run under Win95, and Sound Blaster 1.0 support on a select few (mostly Lucasarts ones it appears). I can use a 256 colour 800x600 display driver also which works pretty well.

Here's a pic of it running Doom under Windows 95 at the recent Cyber Legends event (Robson's pic as I forgot to take any):


I then moved onto OS/2 - Initially I tried Warp 4 - despite some nice UI improvements it was pretty slow on this machine so performed a clean install of Warp 3 into a partition on the 400MB hard drive. Unfortunately both have the issue with the display driver defaulting to a refresh rate none of my monitors will display, so it's stuck in VGA 16 colour mode. The OS itself it a bit of an oddity, with some very nice features and some maddeningly stupid ones, and a nice stable underlying OS that can be basically rendered unusable when the UI crashes which it does a fair amount. Also it has a habit of hard crashing every time a sound is played when the OS/2 CONFIG.SYS file is changed, which is very annoying.

Here's a pic of it in Warp 3:


I've been installing a few games, apps etc and the experience is fairly good for an upgraded 1992/3 era PC. The video card is slow and has compatibility problems but works for the most part, the sound card actually sounds pretty good if you can find an app that uses it properly, and you can take the whole thing apart to motherboard level without a screwdriver. It's been interesting revisiting what things were like shortly after I got my first PC - editing config files to make games run, presenting correct types of RAM, operating systems completely falling over on a whim - but I'm not sure if there is much else I will be doing with this machine.

lilwashu wrote: 24 Jul 2022 18:55 TT Continued
Once the case had dried I reassembled all the shielding and had a closer look at the hard drive cover with the "battery damage" - it was limited to the area with the LED, which had disintegrated, and I am told is due to breakdown of the grommet releasing corrosive gas (The other LED is located in the top shielding and shows no sign of issues):

Some great work on the TT and looks amazing.
Just wondering how you connected a new LED to the wires after it had all disintegrated due to the grommet?
Did you have to strip them down or did the LED slide in to the sleeves on the old wires?

viking272 wrote: 05 Oct 2022 23:24

lilwashu wrote: 24 Jul 2022 18:55 TT Continued
Once the case had dried I reassembled all the shielding and had a closer look at the hard drive cover with the "battery damage" - it was limited to the area with the LED, which had disintegrated, and I am told is due to breakdown of the grommet releasing corrosive gas (The other LED is located in the top shielding and shows no sign of issues):

Some great work on the TT and looks amazing.
Just wondering how you connected a new LED to the wires after it had all disintegrated due to the grommet?
Did you have to strip them down or did the LED slide in to the sleeves on the old wires?

The connections on the old LED had completely disintegrated so I cut the old heat shrink off, desoldered what was left of the old LED and then attached to the new one, added heat shrink etc.

Amiga 1000

Continuing my habit of buying interesting-to-me old stuff in questionable condition for cheap, I came across an Amiga 1000 on eBay. After buying it I noticed severe looking port corrosion on the rear so was a bit apprehensive of what would await me when it arrived:

After checking for any obvious fire hazards I decided to throw caution to the wind and powered it on, to my surprise it booted to the kickstart screen so was mostly working. I continued to strip it down to be greeted to fairly severe rust on the PSU:
I opened it up to check for any lurking RIFAs and found none, so cleaned it up internally and ground the rust off with a dremel then primed and painted. Not perfect but better, and the voltages all measured correctly:
Power sorted out, I ordered some new ports to replace the dissolved ones which I removed with a vacuum desolderer. As right angle 23 pin D subs are not easy to find and the old ones cleaned up fine when the rusty bits were removed, I repurposed the shrouds with some from a scrap A500+ board and reassembled with good results:
Next: Replace ports and see if it still works.