PS/55 Model 5560 Restoration

57 views
Skip to first unread message

Tomas Slavotinek

unread,
Oct 6, 2021, 4:06:26 PMOct 6
to
This puppy arrived a few weeks ago (thankfully in one piece):
https://www.ardent-tool.com/PS55/5560/Dirty_Front.jpg
https://www.ardent-tool.com/PS55/5560/Dirty_Badge.jpg
https://www.ardent-tool.com/PS55/5560/Dirty_Intake.jpg

Yeah it looked rather disgusting, but luckily the plastics weren't
actually yellowed, just really dirty, with a layer of what I presume was
cigarette tar covering everything.

For those unaware, the PS/55 Model 5560 is basically an improved version
of the PS/2 Model 90. The machine has two extra MCA slots in place of
the memory risers:
https://www.ardent-tool.com/PS55/5560/Dirty_Back.jpg

The SIMM sockets were relocated to the planar (under the PSU). The PSU
can be swung out, for easy access to the memory, similar to Models 85/95:
https://www.ardent-tool.com/PS55/5560/Planar_PSU_Out.jpg

But unlike the 85/95, the machine can be operated with the PSU swung
out, making memory related experiments significantly less annoying (even
compared to Model 90).

To my surprise the machine cleaned up rather nicely... after many hours
of scrubbing and some alcohol/q-tip treatment: :)
https://www.ardent-tool.com/PS55/5560/Front_01.jpg
https://www.ardent-tool.com/PS55/5560/Front_02.jpg
https://www.ardent-tool.com/PS55/5560/Back.jpg

The planar and adapter cards needed more than just cleaning as they were
littered with leaking SMD caps. I've removed all of them and cleaned up
the areas that got hit by the leaked electrolyte...
https://www.ardent-tool.com/PS55/5560/Planar_Recap.jpg

...and then reinstalled a few caps here 'n there and decided to test the
board. Unfortunately the original PSU was (and still is) unstable, so I
had to hack together something using a standard ATX PSU. This is totally
safe, I promise!
https://www.ardent-tool.com/PS55/5560/Planar_ATX_Test_01.jpg
https://www.ardent-tool.com/PS55/5560/Planar_ATX_Test_02.jpg

Yay, It works!
https://www.ardent-tool.com/PS55/5560/Screen_01.jpg
https://www.ardent-tool.com/PS55/5560/Screen_02.jpg
https://www.ardent-tool.com/PS55/5560/Screen_03.jpg

Some of the SIMM positions are unreliable and I've since narrowed that
problem down to the process complex board. The planar itself is ok (and
fully recapped now).

Aside from the major design changes mentioned above, there are also many
smaller tweaks everywhere. For example, the system has a provision for a
95-ask Operator Panel:
https://www.ardent-tool.com/PS55/5560/Planar_Front_IO.jpg
https://www.ardent-tool.com/PS55/5560/Panel_Chassis_Stripped.jpg
https://www.ardent-tool.com/PS55/5560/Panel_Chassis_Populated.jpg
https://www.ardent-tool.com/PS55/5560/Panel_Cover_Removed.jpg

Nope, that front panel cover is not removable on a regular Model 90.

The volume pot comes standard with most machines from the PS/55 line. (I
wonder why this was a thing in Japan. These were business machines, and
business software is usually silent... hmm.)

Among the "quality of life" improvements are also these brackets (or
handles?) on the back side of the system. They make opening the unit
much easier:
https://www.ardent-tool.com/PS55/5560/Cover_Slide_Bracket.jpg

Even something as trivial as the MCA slot covers was modified for easier
removal/installation:
https://www.ardent-tool.com/PS55/Pics/Photos/MCA_Slot_Covers.jpg

But there are also some oddities... Like the case lock - it was
relocated to the top cover:
https://www.ardent-tool.com/PS55/5560/Cover_Lock.jpg

And then there's this strange shortened slot cover:
https://www.ardent-tool.com/PS55/5560/Back_Short_Slot.jpg

There's nothing behind it, no unused headers on the board (aside from
the op panel connector), or anything else. Any ideas?

I've updated the 5560 page with the new information and photos:
https://www.ardent-tool.com/PS55/5560/5560.html

And added a 5560 PSU page here:
https://www.ardent-tool.com/PS55/5560/Power.html

What an interesting machine! It's like a Model 90 from a parallel
universe...

Anyway, the tasks left are the PSU repair/restuffing and diagnostic of
the complex memory issue. And then experiments with the normally
unsupported Type 4 platform.

Louis Ohland

unread,
Oct 6, 2021, 9:25:25 PMOct 6
to
https://www.ardent-tool.com/PS55/Pics/Photos/MCA_Slot_Covers.jpg

Recovering after a wild animal instinct party...

Tom, remember the 7012 Thick/Thin Ethernet Riser P/N 52G4737, FRU
43G0382 Card 2-8 ?

https://ardent-tool.com/RS6000/7012/7012_common.html

Since we have zero Japanese Announcement Letters, we'll probably never
know. BUT remember the Japanese CAD Station brouchure that Sandy sendt?


https://ardent-tool.com/PS55/Docs/PS55_Model_5560-N.pdf

Little Wanna-Be RS/6000... "I think I can, I think I can..."

Louis Ohland

unread,
Oct 6, 2021, 9:35:06 PMOct 6
to
Control is not convinced there is a problem...

Tom, I can say with experience that the slot cover blank can and will
cut you open if you let it.

Blood for Micro Channel!

Remember, IBM loved to reduce costs. They loved automated assembly.
Wonder how the PS/55s were assembled. With that tab sticking out, how
were the slot covers fed to the picker? The basic covers we have could
be loaded in magazines, I bet. Think of something like staples? each one
fits into the next one....

Perhaps. Maybe IBM Japan figured hand assembly of the blank covers could
be reduced with more populated adapters? Dunno.

Louis Ohland

unread,
Oct 6, 2021, 9:47:29 PMOct 6
to
Huh... Replaceable power switch / volume front panel... Unpopulated OP
Panel header.

Suggestive of an earlier OP Panel with a display? Probably designed with
it, then they figured out they could get by without it.

Think of the B: Bay display in the 5494.

https://ardent-tool.com/5494/5494.html#Op_Panel


On 10/6/2021 15:06, Tomas Slavotinek wrote:

Louis Ohland

unread,
Oct 6, 2021, 9:53:14 PMOct 6
to
You said "strange" like it's a bad thing.

https://ardent-tool.com/RAID/RAID_Cheetah.html#Cheetah_Side_Card_Front

Bulkhead bracket for a card with an internal port? SCSI? Multi-port?


On 10/6/2021 15:06, Tomas Slavotinek wrote:

Tomas Slavotinek

unread,
Oct 7, 2021, 3:43:26 AMOct 7
to
Yeah that's what came to my mind too, the 2-8 adapter has a full-sized
bracket I think, but both are positioned awkwardly above the I/O area.

Speaking of which, the right most portion of the I/O area is completely
unused on the 5560 planar, so I wonder why didn't they shorten it to
make space for a regular slot cover?

Maybe they though it would be confusing with no actual MCA slot behind
it (and adding another MCA slot would be a problem, since the planar
already kinda has 8 slots - 6x MCA + 2x unpopulated DBA). A regular MCA
cover would be more useful, especially for connector brackets (like the
5.25" floppy connector).

Perhaps they wanted to retain the extra I/O space for later development
- second serial port, on-board video...

Or there really was something like the 2-8 adapter planned for the 5560
originally.

We may never know...

The cover is still useful, ideal for a reset button, SD card slot, etc.

Tomas Slavotinek

unread,
Oct 7, 2021, 3:58:05 AMOct 7
to
There was plenty of blood involved when disassembling/reassembling the
machine, even with all these small improvements :-D.

Were the slot covers really installed by machines in the PS/2 world? I
thought the final assembly was done by humans (adapters, slot covers,
drives, cables...)?

Well, what I know is that these tabs make the covers really easy to
slide out.

Tomas Slavotinek

unread,
Oct 7, 2021, 4:24:49 AMOct 7
to
It sure looks like they designed the machine with a server model in
mind. Extra slots, op panel, there's even place for the 3-pin Remote
Power-ON header.

I'll measure the chassis opening to see if it's the right size for two
HDLX-2416 LED units, but I think it is. The pinout is similar to the
8595 one (but not compatible):

https://ardent-tool.com/PS55/5560/5560.html#J31_Op_Panel_Connector

I'll try to figure out the remaining 4 pins later on.

The smaller opening to the left of the volume pot is also curious:
https://www.ardent-tool.com/PS55/5560/Panel_Chassis_Populated.jpg

I'm not sure if that part is Op Panel related. To me it looks more like
a provision for audio jacks (notice the two screw holes right bellow).

Louis Ohland

unread,
Oct 7, 2021, 9:31:33 AMOct 7
to
Notice the two small circular holes beneath the odd cut-out? Most likely
mounting holes for the barbed fastener for whatever.

Louis Ohland

unread,
Oct 7, 2021, 9:43:38 AMOct 7
to

U57 "DSKBOOT" 64F3110 PAL
https://www.ardent-tool.com/PS55/5560/5560.html

Got to love the Japanese penchant for labeling things.

U72 64F3110, TI CF61533FN
https://ardent-tool.com/9590/9590_Planar.html#90_planar
https://ardent-tool.com/9590/9590_Planar.html#90_planar_early

Tomas Slavotinek

unread,
Oct 7, 2021, 10:46:14 AMOct 7
to
Yep, IBM Japan FTW!

The PAL seems to be wired to the floppy controller. I'll try to figure
out what exactly is going on there...

The link to the early Model 90 planar reminded me something. YouTube
made me rewatch the old LGR PS/2 Motherlode video and @ 16:17 I've
noticed that his board is cut differently than the one in my early Model
90 (see the area around the fan connector). It also has an additional
PAL device in the "SPARE" position (near the power connector):

https://youtu.be/k2R6bwxQqs8?t=977

(pause the video and use the "," and "." keys to move frame by frame)

Probably even earlier sample...

Louis Ohland

unread,
Oct 7, 2021, 11:33:47 AMOct 7
to
My DIMM memories suggest there was a surface mount PLCC down in the
front right. A year or so ago.

WBSTClarke

unread,
Oct 8, 2021, 10:32:32 AMOct 8
to
Sounds like a major surgical operation. Kudos for the extensive effort.

Tomas Slavotinek

unread,
Oct 10, 2021, 4:06:35 PMOct 10
to
On 7.10.2021 10:24, Tomas Slavotinek wrote:
> I'll measure the chassis opening to see if it's the right size for two
> HDLX-2416 LED units, but I think it is.

The opening is 60 x 26 mm in size - just about perfect for the dual
HDLX-2416 setup:

https://www.ardent-tool.com/PS55/5560/Panel_LED_Display_Fit.jpg

Tomas Slavotinek

unread,
Oct 10, 2021, 5:00:59 PMOct 10
to
Thanks! The cleaning can get really tedious, but from the most part it's
actually fun (at least for me xD) - especially when it comes to the
diagnostic and exploring the system. One can always learn something new
along the way...

I've checked the complex and found some corrosion between a couple of
the card-edge contact pads. You can kinda see it on the scan as well
(below the 487 socket):

https://ardent-tool.com/PS55/Complex/60W1_07G3153_Photo_Back.jpg

Some other pads in that general area were rather crummy looking as well,
even after cleaning, so I had to freshen them a bit with a fiberglass pen.

I've tested the complex again (in the same 8595 box as before) and this
time it was stable, even with all 8 SIMM sockets populated - no memory
errors. Not even after removing/reistalling the complex a few times.

So the last item on the list is the PSU...

Louis Ohland

unread,
Oct 10, 2021, 7:38:56 PMOct 10
to
So... aside from systems that have an op console function, what can be
expected of attempts to add a LED display?

Louis Ohland

unread,
Oct 10, 2021, 7:48:01 PMOct 10
to
Please do. It makes me curious, blue. What is this PAL doing? Is it
memory? Wired to the FDC, that doesn't seem quite sensible.

Does it add function? DSKBOOT seems to suggest something related to
booting, not sure it is O/S related, more like IML? Maybe DSKBOOT
supports DBA-ESDI?

You must.. probe it! Yes!

What pins of the FDC does it connect to? What other components does it
connect to?

How about this for an unsupported rumor... the DSKBOOT connects the FDC
to NVRAM to enable booting from CDROM... ;)

On 10/7/2021 09:46, Tomas Slavotinek wrote:

Tomas Slavotinek

unread,
Oct 11, 2021, 6:00:21 AMOct 11
to
On 11.10.2021 1:47, Louis Ohland wrote:
> Please do. It makes me curious, blue. What is this PAL doing? Is it
> memory? Wired to the FDC, that doesn't seem quite sensible.

Why not? The PAL is sitting right next to the FDC and at least some of
the traces go towards the controller.

> Does it add function? DSKBOOT seems to suggest something related to
> booting,

Yeah... the name. The "DSK" part makes sense - floppy DiSK, DBA DiSK -
could be either (or both) if we go just by the name itself.

> not sure it is O/S related, more like IML? Maybe DSKBOOT supports DBA-ESDI?

That's the thing, everything related to the OS "BOOT" process is handled
in software/firmware. I can't think of anything boot-related that would
require a special HW logic.

The only IML-related thing that requires a special HW is the
E0000-FFFFFh range ROM/RAM switching, but that's implemented on the
processor complex.

> You must.. probe it! Yes!
>
> What pins of the FDC does it connect to? What other components does it
> connect to?

Yep... Probulation time!

> How about this for an unsupported rumor... the DSKBOOT connects the FDC
> to NVRAM to enable booting from CDROM... ;)

:-D I like the enthusiasm, but that doesn't make much sense. The two
components are already connected to the planar I/O bus. Not because they
need to talk to each other directly, but because the CPU needs to be
able to address both of them.

Going by the little information we have currently, I only have one
theory - the PAL handles the FDC reset initialization. The 82077
controller can be switched between 3 different modes (PC AT, PS/2, and
Model 30). This is done by setting two of the inputs in a certain way
when the RESET line is toggled. I'll have to check the datasheet again,
but I don't think this can be achieved with high value pull-up or
something similar in this particular case. So perhaps "DSKBOOT" means
"DiSK controller BOOT"? Though something like "FDCINIT" would make much
sense in this context...

Tomas Slavotinek

unread,
Oct 11, 2021, 6:33:42 AMOct 11
to
The 64F3110 PAL can be found on the following planars:

https://ardent-tool.com/9590/9590_Planar.html
https://ardent-tool.com/PS55/5560/5560.html
https://ardent-tool.com/9533/9533.html
https://ardent-tool.com/2011_2121/2121_Planar.html
(the PS/1 stuff is unfinished and not listed on the Ardent Tool index)

And possibly many more, since we don't always track the PALs/GALs and
other glue...

PS/1 hmm, unless it uses the PS/2 FDC mode, my theory is probably wrong.

Louis Ohland

unread,
Oct 11, 2021, 9:22:07 AMOct 11
to
Huh, 64F3110 is connected to the FDC, the 85F0464 INT/KB/mouse ASIC,
maybe the FDC header, and possumbly the DBA-ESDI connectors [or at least
it WAS].

https://ardent-tool.com/9590/9590_Planar.html

U67 85F0464 ASIC (int/KB/mouse)
U72 64F3110, TI CF61533FN
U84 N82077AA Floppy Controller

Then I see a single line over to U68, a SIMMple logic, 74-series, I
think. U68 sendts a single trace up to 85F0464

https://ardent-tool.com/datasheets/Intel_82077AA.pdf

FDC reset initialization

Huh. So where is this on the Model 8595?

On 10/11

Louis Ohland

unread,
Oct 11, 2021, 10:01:38 AMOct 11
to
Intel has a listing for a PAL to be used on an ISA board under AT mode,
but nothing for PS/2 mode.

I wonder... if this PAL was used on DBA-ESDI systems for some reason.
The 9533 MIGHT have been designed for use with the 2.5" DBA-ESDI that
were used in the ThinkPad 700 720 ?

Tomas Slavotinek

unread,
Oct 11, 2021, 10:51:36 AMOct 11
to
On 11.10.2021 15:21, Louis Ohland wrote:
> Huh, 64F3110 is connected to the FDC, the 85F0464 INT/KB/mouse ASIC,
> maybe the FDC header, and possumbly the DBA-ESDI connectors [or at
> least > it WAS].

Looking at some more detailed photos, there are quite a few connections
between the PAL and the FDC - specifically data lines D0-7 and address
lines A0 and A1 (maybe more). This is part of the planar I/O bus, so
yes, if you see connections that go to the IO/INT controller, that makes
perfect sense as well...

> Huh. So where is this on the Model 8595?

On the 1S1P planar there's a PAL near the FDC as well, but it's a
different P/N.

On 11.10.2021 16:00, Louis Ohland wrote:
> Intel has a listing for a PAL to be used on an ISA board under AT mode,
> but nothing for PS/2 mode.
>
> I wonder... if this PAL was used on DBA-ESDI systems for some reason.
> The 9533 MIGHT have been designed for use with the 2.5" DBA-ESDI that
> were used in the ThinkPad 700 720 ?

It's possible that the PAL implements a few different functions that are
not directly related, but seeing that it's connected to the planar I/O
bus, it probably has nothing to do with the DBA interface (a subset of
the MCA bus, which has no place in the ISA-based PS/2 E and PS/1 systems).

Tomas Slavotinek

unread,
Oct 11, 2021, 11:02:17 AMOct 11
to
How about this:

https://priorart.ip.com/IPCOM/000107744

That would explain the presence of the address/data lines...

And the following items are also a perfect match:

-"a transformer module consisting of a twenty-eight-pin design"
-"Diskette controllers, such as the 82077"

The only part that doesn't match is the date - 1992-Mar-01.
That seems rather late, it should be more in the 1989-1991 ballpark.

Here are some other more or less related TDBs:

https://priorart.ip.com/IPCOM/000110084
https://priorart.ip.com/IPCOM/000110375
https://priorart.ip.com/IPCOM/000110377
https://priorart.ip.com/IPCOM/000036919

On 11.10.2021 16:51, Tomas Slavotinek wrote:

Louis Ohland

unread,
Oct 11, 2021, 11:45:40 AMOct 11
to
On 10/11/2021 10:02, Tomas Slavotinek wrote:
> transformer module

Tomas Slavotinek

unread,
Oct 11, 2021, 12:15:41 PMOct 11
to
On 11.10.2021 17:44, Louis Ohland wrote:
> On 10/11/2021 10:02, Tomas Slavotinek wrote:
>> transformer module

Patent speech at its best...


Louis Ohland

unread,
Oct 11, 2021, 12:59:05 PMOct 11
to
Read the IPs, nothing mind-blowing. Mention of DMA arbitration, 82072
compatibility. Some mentions in the datasheet about inverting a signal,
dunno if this was just internal to the 82077AA, or if it has to be
actually inverted externally.

Louis Ohland

unread,
Oct 11, 2021, 2:18:33 PMOct 11
to
The gate array interface circuit is primarily intended to be used with
the Intel 82077 diskette controller so as to provide compatibility with
DMA controllers which transfer only one byte of data. Diskette
controllers, such as the 82077, contain a sixteen-byte first-in,
first-out (FIFO) buffer, such that there is a possibility whereby a
second or more bytes can be transferred if the data from the diskette
drive is not transferred in time. Without compatibility between the two
controllers, a time-out condition can occur.

So. The Model 90 DMA controller can't do better than one byte of data?

DATA 0-7
-BURST IN, BURST OUT
ADDR 0-2
MDS0-2
CS, RD, WR
MMEN0
MNEN1-2
MET0-1
DRVT0-1

Looking at this, the BURST IN/OUT makes sense, if the DMA controller was
limited. Just not accepting that the Model 90 has a byte wide DMA
controller.


On 10/11/2021 10:02, Tomas Slavotinek wrote:

Louis Ohland

unread,
Oct 11, 2021, 2:27:23 PMOct 11
to
The Model 90 maintains hardware compatibility with the Intel 8272
diskette drive controller.

Tomas Slavotinek

unread,
Oct 11, 2021, 2:50:41 PMOct 11
to
The DMA controller is on the complex, so it depends.

The Model 90 XP in particular was designed with the Type 0 complex in
mind, but we can't say the same thing about the 95 XP. So maybe this has
to do with the 386-era chipsets... that is if we are right about the
DSKBOOT PAL and its function.

There are also some additional restrictions posed on the planar I/O
devices, in regard to the bus width, streaming modes, etc. But I'm not
sure if it adds any DMA restrictions to the mix.

Louis Ohland

unread,
Oct 11, 2021, 3:04:17 PMOct 11
to
The 90 SSI says the DMA controller can work with 8 bit and 16 bit DMA
slaves. Also, the Type 2 FDC comes up as a Type 1, and uses Type 1 mode
to accept all commands. Way past me.

Tomas Slavotinek

unread,
Oct 11, 2021, 3:19:53 PMOct 11
to
The 90 and 95 SSI only cover the Type 1 complex unfortunately (it has
specs for "Type 1" and "Type 2", but what that really means is Type 1
"J" and Type 1 "K").

Anyway, we need more info about the actual circuit. I'll try to probe
the planar tomorrow, if the time allows...

Tomas Slavotinek

unread,
Oct 11, 2021, 3:32:28 PMOct 11
to
Actually the Type 1 and Type 0 complexi use the same DMA controller,
originally from the 50Z/55/65/70. Hmm... moar data needed.

RickE

unread,
Oct 15, 2021, 11:09:00 AMOct 15
to
On Monday, October 11, 2021 at 11:02:17 AM UTC-4, Tomas Slavotinek wrote:
> The only part that doesn't match is the date - 1992-Mar-01.
> That seems rather late, it should be more in the 1989-1991 ballpark.

Don't get too hung up on the date, back in the 90s IBM Legal would routinely take *forever* to finally decide to pursue a patent on something -- especially a rather "simple something" like this patent. Things that had obvious commercial value got patents quickly, hundreds of other invention disclosures could sit in limbo for a long time.

Tomas Slavotinek

unread,
Oct 15, 2021, 5:12:54 PMOct 15
to
Fair point!

Tomas Slavotinek

unread,
Oct 15, 2021, 5:44:14 PMOct 15
to
I've probed the 5560 planar and here is the pinout of the 64F3110 PAL:

pin 1: DB2
pin 2: DB1
pin 3: DB0
pin 4: *unknown*
pin 5: Ground
pin 6: *unknown*
pin 7: A0
pin 8: A1
pin 9: A2
pin 10: -RD
pin 11: -WR
pin 12: FD conn. pin 9: Drive Type ID0 (TDB: "DRVT0")
pin 13: FD conn. pin 4: Drive Type ID1 (TDB: "DRVT1")
pin 14: FD conn. pin 40: -Motor Enable 2 (TDB: "MMEN2")
pin 15: FD conn. pin 12: -Drive Select 0 (TDB: "MDS0")
pin 16: FD conn. pin 36: Drive Select 2 (TDB: "MDS2")
pin 17: FD conn. pin 27: Media Type ID0 (TDB: "MET0")
pin 18: FD conn. pin 17: Media Type ID1 (TDB: "MET1")
pin 19: *unknown*
pin 20: Vcc (+5 V)
pin 21: FD conn. pin 10: -Motor Enable 1 (TDB: "MMEN1")
pin 22: FD conn. pin 14: -Drive Select 1 (TDB: "MDS1")
pin 23: FD conn. pin 16: -Motor Enable 0 (TDB: "MMEN0")
pin 24: DB7
pin 25: DB6
pin 26: DB5
pin 27: DB4
pin 28: DB3

(pin 1 is marked by a dot and from there it goes counter-clockwise when
looking from the top on the package)

Compare it to the "Gate Array Interface for Disk Controller" diagram:

https://priorart.ip.com/first-page/IPCOM000107744D

Yep, pretty much a perfect match!

The 3 unknown pins will be -BURST_IN, BURST_OUT, and CS (chip select)
most likely. They probably go to some other glue logic somewhere on the
board... I didn't want to disassemble the machine again just because of
this.

So, the PAL mostly deals with the Drive Select, Motor Enable, and
Drive/Media signals. And possibly with the BURST translation as well.
Err, why is it marked as "DSKBOOT" again? :-D

On 11.10.2021 20:17, Louis Ohland wrote:

Louis Ohland

unread,
Oct 15, 2021, 6:28:07 PMOct 15
to
DIMM surprise. I am unaware of any need for diddling with arbitration or
the DMA controller, yet here is a solution possumbly looking for a
problem. The only plausible issue I have seen is interfacing a non-FIFO
DMA controller to a FIFO equipped FDC. Maybe it's the 85F0464
INT/KB/mouse ASIC that has the issue? Dunno.

Where's the plum brandy?

Louis Ohland

unread,
Oct 16, 2021, 2:55:53 PMOct 16
to
Tom, I looked again, not sure. Any leads from 64F3110 go to anything
else other than the ASIC and FDC?

Tomas Slavotinek

unread,
Oct 16, 2021, 4:40:23 PMOct 16
to
On 16.10.2021 20:55, Louis Ohland wrote:
> Tom, I looked again, not sure. Any leads from 64F3110 go to anything
> else other than the ASIC and FDC?

The address and data lines are shared with the FDC and the other planar
I/O devices.

The floppy interface signals go directly to the floppy connector (not to
the FDC).

The 3 unknown lines go who knows where... probably some glue. I may
revisit this later on, when I have one of the planars with the 64F3110
PAL on the workbench...

Tomas Slavotinek

unread,
Oct 18, 2021, 12:16:21 PMOct 18
to
Here is how I've solved the PSU problems and why:

https://www.ardent-tool.com/PS55/5560/Power_ATX_Mod.html

The same method could be used for the Model 90 PSU.

The machine is finally up n running:

https://www.ardent-tool.com/PS55/5560/Done_01.jpg
https://www.ardent-tool.com/PS55/5560/Done_02.jpg
https://www.ardent-tool.com/PS55/5560/Done_03.jpg

My LCD didn't like the interlaced "115.2 Hz" mode... had to switch to my
trusty Targa CRT for the Windows session:

https://www.ardent-tool.com/PS55/5560/Screen_04.jpg
Reply all
Reply to author
Forward
0 new messages