On Wed, 05 Apr 2000, Hans-Peter Zeedijk wrote:
> Second, there is a 1Mb pc SIMM module with a homemade PCB with the texts
> F.U.C. JIPE OCT1994.
French United Coders, the name they had before they joined IOD.
The 1Mb was probably installed by Martial Benoit.
> Third, a small homemade PCB with 4 74HCTXXX chips on it connected with a lot
> of wires all over de mainboard.
There many different 74HCT chips. I used several for making an ESE-SCC.
Your device could be part of the 1Mb memory mapper, it could be an expanded
slot, it could be a mega RAM of some kind or it could be something else.
> 1) How do I connect an external floppydrive on that 15 pin D-sub female
> connector and can I make the drive select switchable between 1st and 2nd
> floppy?
I have a description with the pin numbers from the turbo R mainbord. So if
you write down the mapping from the mainbord to that 15 pin connector, you
can combine the two and you know the mapping of the connector.
I don't think there is any offical standard of mapping floppy signals to
such a connector.
By the way, connecting a PC drive to a turbo R is not easy. The problem is
that the turbo R requires both a "ready" (RDY) and a "disk change" (DC)
signal. Recent PC drives no longer have these signals.
Preferably, you find an old PC drive (286 era) which does support this
signals. If you cannot find it, you can use a modern drive, although
it's suboptimal.
To fake a ready signal, connect it to the "disk inserted" sensor. It will
always report ready when a disk is inserted. This makes the drive operate a
bit slower and more noisy because it needs some retries when the drive was
in fact not ready, but it does work. If your drive doesn't have a "disk
inserted" sensor, use the HD sensor instead and use only DD disks or HD
disks with the HD hole taped over.
To fake a disk change signal, always return "disk changed". This means the
DOS2 cache for the floppy is always flushed, so it will cost some
performance. As far as I remember, disk change is low active, so to return
"disk changed" at all time, you must connect it to the ground.
> 2) Will I have to use a floppydrive with its own powersupply or does this
> come with these wirering?
Most floppies only need +5V, you can get that from the turbo R floppy
connector. If your floppy does need +12V, you can get it from the power
supply of the turbo R.
> 3) What is happened to the original 512kb memory? The total memory reported
> while booting is 1Mb and that is same as the 1Mb SIMM.
Maybe is was put in a different slot? Try loading Memman or another program
that counts memory in all slots and see how much it reports.
Bye,
Maarten
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