Unkown hardware on this Mega ST

[+DarkLord]

I picked up this DOA Mega ST this week. I swapped out power supplies and got it booting

up at least. Lots of issues with it, but I'm working on them one at a time.

 

Meanwhile, I noticed some hardware I wasn't familiar with. Here are a few pics:

 

 

As you can see, there is a small PCB with a ribbon cable that attaches to the Floppy

Drive controller chip.

 

 

This part is easy - its one of Jim Allens Fast Technology's T16 accelerators.

 

 

This is a closer view of the PCB.

 

 

and this is a closer view of the header someone added to the FDC chip, that

the ribbon cable from the PCB attaches too. There are a few other wires there

you can see as well, that were added.

 

Is this all part of the T16's installation or something else? I'd think else.

 

Thanks everyone.

[anzac]

ok, i might be going out on a limb here, since i don´t recognise the PCB also, but could it be some upgrade to use a 1.44mb floppy?

[+DarkLord]

ok, i might be going out on a limb here, since i don´t recognise the PCB also, but could it be some upgrade to use a 1.44mb floppy?

 

Thought about that too - but it looks like a standard ST floppy disk drive (complete with big eject button)

thats in the case.

 

Thanks for the reply.

[anzac]

yeah, i noticed the standard floppy, but thought that there was a chance. who knows, maybe it is a 1.44mb floppy with the normal big button face?

 

pictures are not clear enough to distinguish that detail...

[+DarkLord]

I'll fire it back up in the next couple of days and stick a 1.44 floppy in it

and see if it reads it or gets indigestion.

[+DarkLord]

Okay, I tried a couple of different 1.44 floppies and it will not read them.

 

Examining that board a bit closer, there are some chips marked with "UK"

on them - I guess its from England...

 

Anyone have any further ideas? Thanks.

[krupkaj]

Can you make better photos? It is not possible to read IC identifications

[+DarkLord]

Sorry, having trouble finding a decent camera around here - got an older one that takes blurry pictures, and my

sons, which takes great pictures, but each one is like 50-100megs in size (must be a WINcam).

 

Anyways, here are some of the chips on the small PCB:

 

74LS00 PC

74LS32 PC

WD2793CL-02

 

2 chips that I can't make out, a 12 pin block with 2 jumpers on it (named JP1), something

called SPECTROL UK (50K-K 6068 UK), and what I think is a serial number on the board

itself, 05259002.

 

Don't know if that helps or not.

 

Thanks.

[+poobah]

Sorry, having trouble finding a decent camera around here - got an older one that takes blurry pictures, and my

sons, which takes great pictures, but each one is like 50-100megs in size (must be a WINcam).

 

Anyways, here are some of the chips on the small PCB:

 

74LS00 PC

74LS32 PC

WD2793CL-02

 

2 chips that I can't make out, a 12 pin block with 2 jumpers on it (named JP1), something

called SPECTROL UK (50K-K 6068 UK), and what I think is a serial number on the board

itself, 05259002.

 

Don't know if that helps or not.

 

Thanks.

 

Well, the 2793 is a floppy controller, I believe they were used for the Happy drive mods.

Maybe it is an internal Happy setup?

[+Stephen Moss]

my sons, which takes great pictures, but each one is like 50-100megs in size (must be a WINcam).

I assume it is digital, if so then reduce the number of pixes used, 2M pixel is quite accecptable you may even be able to get away with 1M pixel but Macro mode is always good to use for those blur free close ups.

Anyways, here are some of the chips on the small PCB:

 

74LS00 PC

74LS32 PC

WD2793CL-02

 

2 chips that I can't make out, a 12 pin block with 2 jumpers on it (named JP1), something

called SPECTROL UK (50K-K 6068 UK), and what I think is a serial number on the board

itself, 05259002.

 

Don't know if that helps or not.

 

Thanks.

74LS00 is a Quad 2 input NAND gate

74LS32 is a Quad 2 input OR gate

I could not find anything conclusive on the WD2793CL-02, some old IC Masters books do list a Veronix and Texas device with a 2793 prefix as a single sided floppy controller device but that is no guarentee that the WD2793CL-02 is also a floppy controller and even if it is why use a single sided one when presumable the Mega already has a floppy controller chip that can handle single sided discs?

The Specrol UK item is I presume the square yellow item in the corner and is just a preset pot (variable resistor).

The round item in the corner next to that appears to be a variable capacitor and may be being used in conjunction with the resistor as part of a clock circuit.

 

Some IC's have poor printing in which case tilting the IC can sometimes make it easier to read or the information may have been ground off to prevent copying in any event they are not large and are probably just more simple logic devices.

[+DarkLord]

Okay thanks for all the info everyone.

 

Actually, I was only able to read 2 of the chips by tilting it sideways,

as you said, in strong sunlight.

 

Well, I dunno - since it doesn't read any 1.44 meg floppies I've

thrown at it here, I'm not sure what to think.

 

Does anyone know if the 1.44 meg upgrades required any software

(AUTO folder or whatever) to work correctly? I didn't think they did.

 

Thanks.

[Tempest]

Maybe the upgrade is broken?

 

Tempest

[+DarkLord]

Maybe the upgrade is broken?

 

Tempest

 

Yep, thats a thought that had crossed my mind. But without docs or anyone even

being able to recognize the darn thing, kinda hard to tell...