Extended clone of the great Vortex F1-D/M1-D Floppy Disc Controller!

Started by GUNHED, 20:09, 08 August 21

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Would you be interested in an additional FDC for your CPC/Plus supporting 4 drives (DOS exists)?

Yes, that would be awesome!
Maybe, let's see...
No, but I'm reading this thread nevertheless, because it's cold out there

GUNHED

Somebody able to clone the DDI-1 with changed I/O addresses?
This way we would have the Vortex F1-D controller, AND SOFTWARE IS ALREADY THERE :-)
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eto

If the link you provided is already a DDI clone, it would be an option to get the PCB from Wolfgang Harvard, assemble it and just bend one pin (the one that goes to A7) of one chip upward and connect it to A3 with a wire.

GUNHED

Yes, and than all a little 2 to 4 decoder (from the two DS pins of the FDC to the four signals DS0, 1, 2 and 3) to be able to use for drives. 
Sure and simple thing for somebody who is capable to do hardware.  :)
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eto

Quote from: GUNHED on 20:18, 06 April 22Yes, and than all a little 2 to 4 decoder (from the two DS pins of the FDC to the four signals DS0, 1, 2 and 3) to be able to use for drives. 
Maybe I don't get it: That controller is DDI compatible and already supports 4 drives. The developer is selling the PCBs and the chips are easily available. What's still missing? 

Audronic

Quote from: eto on 23:23, 06 April 22
Quote from: GUNHED on 20:18, 06 April 22Yes, and than all a little 2 to 4 decoder (from the two DS pins of the FDC to the four signals DS0, 1, 2 and 3) to be able to use for drives.
Maybe I don't get it: That controller is DDI compatible and already supports 4 drives. The developer is selling the PCBs and the chips are easily available. What's still missing?
@eto 
Do you have a link to the developer please

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TotO

May be I'm wrong, but if DS0 = on/off to select drive A and DS1 = on/off to select drive B at best you will have drive A and drive B off with 00, drive A only with 01, drive B only with 10 and drive A+B with 11 (drive C if it is not possible to have both at the same time) so 2 or 3 drives but not 4. No?
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eto


eto

Quote from: TotO on 08:44, 07 April 22May be I'm wrong, but if DS0 = on/off to select drive A and DS1 = on/off to select drive B at best you will have drive A and drive B off with 00, drive A only with 01, drive B only with 10 and drive A+B with 11 (drive C if it is not possible to have both at the same time) so 2 or 3 drives but not 4. No?


DS0 and DS1 on the chip are not the DS0 and DS1 on the cable. I found some other docs (http://cpctech.cpc-live.com/docs/upd765a/necfdc.htm), where these pins are called US0 and US1 - Unit Select, 2 bits which encode 4 values, and they are meant to be decoded externally.

US0,US1 (Unit Select 0,1)
The US0 and US1 outputs select up to 4 floppy disk drive units an external decoder.
From the schmeatics of the DDI I understand that 00=A, 01=B. 10 and 11 are not used. On the controller that Gunhed found, DS0 and DS1 are both used and decoded, so it support 4 drives.

TotO

So, you have US0 and US1 as input of a demux (74HCT139) to decode 00, 01, 10, 11 to output 4 drive select, that mean there is always one drive selected and you can't use more that one drive at the same time. It can be good as you only have one motor-on signal for all the drives at end... Probably "/RW /SEEK" can allow to trigged the demux IC to be able to have all the drive disabled if needed.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

eto

Quote from: TotO on 09:47, 07 April 22So, you have US0 and US1 as input of a demux (74HCT139) to decode 00, 01, 10, 11 to output 4 drive select, that mean there is always one drive selected and you can't use more that one drive at the same time. It can be good as you only have one motor-on signal for all the drives at end... Probably "/RW /SEEK" can allow to trigged the demux IC to be able to have all the drive disabled if needed.

I guess that's exactly how the CPC/DDI works, right? Always one drive selected, and motor on for all drives at the same time. 

GUNHED

Quote from: TotO on 09:47, 07 April 22So, you have US0 and US1 as input of a demux (74HCT139) to decode 00, 01, 10, 11 to output 4 drive select, that mean there is always one drive selected and you can't use more that one drive at the same time. It can be good as you only have one motor-on signal for all the drives at end... Probably "/RW /SEEK" can allow to trigged the demux IC to be able to have all the drive disabled if needed.
I'm not sure to understand you. The 2 to 4 decoder is used in lot of Z80 computers with FDC765. It's standard, just Amstrad didn't do it so save few bucks. Back the day it was probably ok, to have two drives of 3" only. But then 5,25" and 3,5" become more important and suddenly one does miss few more drives.

Switching between the drives is not needed, because the commands for the FDC do contain a drive number (00..11 binary). So you can access every drive, there is no switch. Only few command are for all drives.

Having a motor-on signal for every drive would be nice somehow, but it would make everything incompatible (like the existing VDOS 2.11 for the F1-D controller).
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TotO

Just give me an example of computer using a standard FDC that natively support more than 2 floppy disc drives? I don't get it.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

GUNHED

Quote from: TotO on 16:37, 07 April 22Just give me an example of computer using a standard FDC that natively support more than 2 floppy disc drives? I don't get it.
NEC Decision mate
TRS80 Model IV, III, others
Genie IIIs, III, II, IIs
and most Z80 CP/M computers
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TotO

I will take a look. Thank you. I'm surprised that you said "most Z80 CP/M computers" while the OS support floppy drives on A and B letters.
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

GUNHED

Seems to be common for most home computers to be able to use two floppies only, because they needed to be produced cheap to fill the companies purse. 
In business, where computers are more expensive anyway, the possibility of four drives was common. However the majority of them came with one or two drives. Back the day a drive was something around $1000. Floppy 3 and 4 could be added externally.
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TotO

I couldn't find anything about that. All the computers you list use 1 or 2 floppy drives.

However, I have seen that IBM PCs are able of use 4 floppy drives under DOS by plugging two drives into the internal connector and two drives into the external connector. It require to move the hard drive to E: and they take place in A:, B:, C:, D: letters!

Now I think it is necessary to do what I explained before to be able to connect 4 floppy drives to an external Vortex interface clone.
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GUNHED

If you can't find it... stop searching the internet (it's too young!) get startet with real paper. 

Back on topic... We want to clone the DDI-1 controller with two simple alteratioins:
- 2 to 4 decoder, from 2 DS signals of the FDC to four DS signals at the floppy (Shugart) cable.
- Adapted base address

Basically it's very simple to do this - for an hardware person.
Well, I'm not - I do software.
Is somebody capable of doing such an floppy controller ?
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TotO

Quote from: GUNHED on 00:48, 08 April 22Back on topic... We want to clone the DDI-1 controller with two simple alterations:
- 2 to 4 decoder, from 2 DS signals of the FDC to four DS signals at the floppy (Shugart) cable.
It is what I have said (may be using RW /SEEK as trigger).
"You make one mistake in your life and the internet will never let you live it down" (Keith Goodyer)

GUNHED

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Prodatron

Quote from: TotO on 19:03, 07 April 22I couldn't find anything about that. All the computers you list use 1 or 2 floppy drives.
That's not a surprise. It was an oddity to have more than 2 floppy discs, as instead of having 4 disc drives you choosed a harddrive already in the late 80ies.
In 2022, when many CPCs even don't use their original internal 3" drive anymore, but a HxC/Gotek/M4/SF3 etc. it sounds even more strange to have 3 or 4 floppy disc drive. And as it wasn't usual in the 80ies I don't think that 3 or 4 floppy drives are really a typical retro thing.

GRAPHICAL Z80 MULTITASKING OPERATING SYSTEM

GUNHED

It's a big difference to have two drives connected and have the possibility to use four at the same time (regular Z80 computer setup) - or to have one/two drives connected and have the possibility to use NOT more then two at the same time (setup of cheap home computers).

This topic is for recreating the Vortex F1-D floppy disc controller. But if I look at the recent posts I guess it's the wrong forum: No help, just strange comments. How sad!
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GUNHED

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GUNHED

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