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14Dec/180

Sony HITBIT HB-F1XD Floppy Drive

Hello again Mr HIT BIT. I bought this unit a while back and never got around to testing the floppy drive...

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As you can see from the image below, there was a sticker attached that said the Floppy drive was problematic. (フロッピーディスクは動作しません)

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This didn't worry me too much, as I intended to use the cartridge slot more than the floppy drive. Regardless, I wanted to eventually test it out. I actually even bought a random second-hand disk from a second-hand shop in Japan whilst purchasing the main unit.

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Based on the sticker... the first goal was to inspect the drive!

Pulling the unit apart

In full Sony-style, there's 6 screws (with arrows pointing to them!) on the underneath of the unit that need to be undone. Once they're out, flip the unit back on its base and remove the cover left-to-right. The floppy disk eject button is seated through a hole in the top half of the case, so be careful when removing!

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Once off, there's a shield on top of the floppy drive to remove. This has one screw top-right. Undo the screw and then use a flat-head screwdriver to prize off the clips along the back of the floppy drive. After this, there are then three screws that hold down the bracket that the drive is attached to. With these out, you can then perform a back-flip with the drive and expose the wiring. It turns out it's a 34-pin data cable and standard floppy drive power cable!? But with only the 5v wiring.

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The drive itself

Things got interesting from here... after removing the top case (more clips, use a flat-head screwdriver), I noticed that there didn't seem to be a drive-belt at all. All articles online indicated that these drives had belts and are known to perish over time. I started pulling the drive apart further and found out that Sony actually chose to split the drive motor across the base PCB!? Talk about a nice way to save space... and not have to need a belt!

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Talk about mesmerising... those copper coils are beautiful! But dang... I'd gone and bought a belt and everything... if this still isn't working, as per the sticker, then I'm really in trouble!

Testing the drive

I put it as-back-together-as-needed to test the drive and turned it all on. I put the disk in, but all was very quiet. My MegaFlashROM loaded into Nextor and I hit the number '2' key to switch to the second drive.

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What? It works? MENU.BAS sounds like a good place to start...

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Ok, here we go... is this a demo disk? "Tanaka Yatsuu Shin"? I'll need a bit of help translating this... regardless, "CG" sounds like fun!

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4 Images? Here they are in order...

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I had it all working nicely, but the machine was half apart... so I screwed it all back together.

Floppy Drive Issues

Once back together, the drive refused to read. Taking it apart bit-by-bit, it started reading again once the drive shell was off... but this wasn't reliable either...

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Gosh-darn... it's time to dig further into this drive... It seems I can wire in a PC drive.. but first I'll open the whole unit up again and give it a proper clean. It felt like it was having issues understanding that the disk was in the drive... I'll start there and determine what sensors are used and if they're functioning correctly... but that's all in the new year!

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11Dec/180

Digital 54-22703-01 Motherboard – L2 Cache

After making this motherboard fit into the IBM PS55/z, I realised I hadn't decked it out fully. I'd mentioned cache in the first post, and finally got around to ordering some. The goal was to speed up the poor old 486 as it wasn't running as fast as I would've expected it to. Of course, this was also all very subjected as it'd be pretty impossible to actually remember how fast my first PC actually ran!

Usually, parts like this can be pilfered from other items laying on the shelves in my apartment, but this motherboard needed specific 'TAG' RAM, as well as the standard 32KBx8 static RAM chips. I had to go hunting...

Required components

Back to Pafe 45 of the User Manual for this motherboard and we find that we need eight 32 KB x 8 cache SRAM chips and three 16 KB x 4 cache tag SRAM chips to max it out. Straight to eBay and I found a seller in Israel with the correct parts. I incorrectly ordered two sets of TAG RAM chips and only half the required static RAM chips... whoops... fortunately I could pilfer those off another board!

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The TAG RAM chips are labelled MCM6290BP25 RIQAB9131.

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As per usual... always be careful when inserting ICs. Make sure their legs are aligned with the sockets and don't press until it's safe... otherwise this happens!

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With everything in, we just need to adjust the jumpers...

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Set all four jumpers (J3,J4,J6,J7) to 2-3... and then boot!

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Yosh!

Test Software

Go here and download anything that starts with Cache. I then tested them all out...

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They all showed that any data size under 256kb proved quick response times. The rest started spiking as more operations were required. The CCT386 application had awesome graphs.

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Now to work out if the games actually operate faster...

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4Dec/180

Microchannel Sounds Cards (aka Hen’s Teeth)

I was interested in these when the IBM PS/55z was on its way as I wanted to deck the machine out with sound. Turns out that MCA is a rare breed and actually-interesting cards are impossible to come by.

Imagine my surprise when I saw an MCA ChipChat Sound Card (with wavetable addon!) appear on eBay. It started at AUD$50 and I was interested... just because it had to be an investment to sell later?

Here's the description...

This a ChipChat Sound-32 Card for a IBM PS/2 Microchannel computer.
It comes with original box and contents. Including reference disk and driver disk.
Drivers are for DOS, Win (3.1, 95, NT), OS/2 (2.x, Warp)

And a few pictures:

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s-l1600 (1) s-l1600 (3) s-l1600 (2)

So yeah, nothing special... not even a mention if it works? Anyway... the 7 days were nearly over and it had gotten up to AUD$141. I was a little disjointed, but yeah... it's a relic! I mean, it's beautiful.. but... I wasn't expecting the outcome:

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I'm very happy that someone, who I hope REALLY REALLY wanted it, got a very nice piece of computing history!

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3Dec/180

Testing EGA/CGA Cards

I'd picked these up a while back but never thought I'd get to test them. I don't have any monitors that support the old standard and haven't actually seen any available on eBay for a long time. I was quite surprised when I realised that the GBS-8200 that I picked up for my MSX would work to convert the frequencies! I'd only ever expected to use it for the MSX RGB signal.

V7 VEGA 8-BIT VGA

This card (thanks, stason.org!) has the ability to output both EGA/CGA and VGA! It's 8-Bit ISA and it a little worse-for-wear...

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This seems to be quite an advanced card of its era. Happily outputting to the monitor you happen to have and allowing for future upgrades! It also even seems to have the VGA auxiliary header?

VIDEO SEVEN V7 VEGA EGA

This card (thanks again to stason.org!) is a little older. It has a header for a light-pen and suppsoedly two composite video inputs!?

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GBS-8200

I had purchased the bare-bones board and never tried it. Thanks to my new desktop power supply, getting it going was really very easy. The board comes with a standard DC jack, but also a pin header for the input voltage. Instead of using a crappy wall-wart, I instead powered it on the supply, having the additional benefit of knowing the current requirement!

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Ian Stedman thoroughly reviewed this board. His outcome was that there were a few issues, but a strong power supply is not needed. It turns out that my testing below shows that it hardly needs 5v at 400mA!

You can see where I've soldered on to for the EGA/CGA input. It's the bottom-right 5-pin header and I couldn't find an acceptable plug. In the end, a quick bit of tinning worked. There's 4 wires: R,G,B, Sync and Ground. The EGA Pinout on Wikipedia (CGA is nearly identical) shows that there are two sync lines, but we only have one on the GBS-8200! As mentioned above, we'll use the bottom-left connector on the board.

Combining HSync and VSync

We'll need to combine the Horizontal and Vertical Sync outputs from the EGA signal as the GBS-8200 requires a single Composite Sync signal. To do this, we can use an XOR or OR gate. Ian is our saviour once again and has provided a circuit to combine the signals.

Build the circuit as he's described. I actually found that either XOR or OR worked fine with the GBS-8200!

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I probably should've tested some games...

Hercules?

No such love. Same connector, but a very different video signal. Turns out it's actually a digital TTL signal that this unit cannot process. If you really want yo convert it then you'll need to buy a GBS8219.

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Is that a printer port? Space saving tech! I don't have any plans to pay for a Hercules monitor or an 8219, so this is going straight on eBay.

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