DocFlareon Posted March 15, 2018 Share Posted March 15, 2018 Can the PHP1240 FDC communicate with IBM-style half-height DSDD drives? Does the PEB's power supply have enough "oomph" to power two drives? I'm hoping to install a couple Atari XF551 drives or two random "IBM" half-height drives. Two drives are practically a must, and I have hopes to one day purchase a MyARC FDC to replace my current PHP1240. Quote Link to comment Share on other sites More sharing options...
RickyDean Posted March 15, 2018 Share Posted March 15, 2018 Can the PHP1240 FDC communicate with IBM-style half-height DSDD drives? Does the PEB's power supply have enough "oomph" to power two drives? I'm hoping to install a couple Atari XF551 drives or two random "IBM" half-height drives. Two drives are practically a must, and I have hopes to one day purchase a MyARC FDC to replace my current PHP1240. Yes two 'IBM' style half-height drives will work in a PEB, have used this setup alot in the past. Just be sure they are jumpered correctly and the last drive is terminated. The two drives are almost never operating at the same time anyhow, so the impact to the power-supply is negligible. Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted March 15, 2018 Share Posted March 15, 2018 Yes two 'IBM' style half-height drives will work in a PEB, have used this setup alot in the past. Just be sure they are jumpered correctly and the last drive is terminated. The two drives are almost never operating at the same time anyhow, so the impact to the power-supply is negligible. Not entirely correct. The interface only has a single motor control line (/MO or /MOT) and a lot of drives I have been testing will spin even if not selected*. Some computers depend upon this and will not wait for a newly-selected drive to spin up if the motor control is already active. Even so, the half-height drives usually draw far less power than the full-height monsters. * Some have a jumper to change this behavior. 1 Quote Link to comment Share on other sites More sharing options...
DocFlareon Posted March 15, 2018 Author Share Posted March 15, 2018 Okay, so if I install two half-height drives as dsk1 and dsk2, I can then have a floppy emulator such as an HxC acting as DSK3. Just one question here. How do I terminate the chain? Bonus question: Does the PHP1240 care if a twist-cable is used between it and the two internal drives? If the FDC does care, how can I find and purchase an untwisted two-drive cable? Quote Link to comment Share on other sites More sharing options...
atrax27407 Posted March 15, 2018 Share Posted March 15, 2018 I have been using two half height 3.5" IBM-type drives in my P-Box for about 15 years now. They are the old 720K drives so I don't have to worry about the density hole being covered. I also have a 5.25" half height drive as DSK3. All work without any issues. I might even have an extra cable (without the twist). Let me know if you need one and I'll look and see if I have a spare. Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted March 15, 2018 Share Posted March 15, 2018 If you are going to have three drives IN the box then you will need a custom cable, anyway, as standard PC cables are three position (one for the controller and two for the drives.) Though the drive positions may be both IEC header and card-edge. In any case, twisted or not, you have to pay attention to the drive select jumper settings. DSK1 = DS0 or SEL0, DSK2 = DS1 or SEL1, etc. Now, to be perfectly honest, I do not know for certain if you can use a twisted cable. I believe you can since usual twists just flip-flop the DS0, DS1, and ground lines in-between. Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted March 15, 2018 Share Posted March 15, 2018 What I learned was "no twisted cable on TI99". Means, I never got it running, in any jumper position on the drives. So I just opened the plug carfully and just turned the twisted cable back to straight, and closed it again by pressing together. Not a good & clean way, but works for me when having no correct straight cable. 1 Quote Link to comment Share on other sites More sharing options...
marc.hull Posted March 15, 2018 Share Posted March 15, 2018 Yes you can safely power 2 - 1/2 height drives in the PEB. No you can not use the twisted cable. If you want 3 drives in the box you will need 1/3 height drives. Hard to mount (physically) but can be done. 1 Quote Link to comment Share on other sites More sharing options...
+OLD CS1 Posted March 15, 2018 Share Posted March 15, 2018 If I could get these bloody Epson combo drives to run at 300RPM I could mount FOUR in my PEB!! 1 Quote Link to comment Share on other sites More sharing options...
DocFlareon Posted March 16, 2018 Author Share Posted March 16, 2018 Thankfully, Arcadeshopper sells untwisted cables and mounting adapters for half-height drives. So I'll be good to go once I source a couple drives. Now if only a DD-capable FDC were to make itself available for a sane price. 1 Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted March 16, 2018 Share Posted March 16, 2018 On the drives, do stay away from Qume 5.25 inch drives if you want to put two into the PEB--they draw too much power. On Myarc controllers, I'm working on that (I have some test boards that I need to troubleshoot so that I can finalize my updated layout). I should finish that sometime this year. . .probably late in the year, though, as my hobby time has been limited for quite a while due to work. 1 Quote Link to comment Share on other sites More sharing options...
apersson850 Posted March 16, 2018 Share Posted March 16, 2018 (edited) I've had two Teac FD-55B drives in my PEB since I bought it in 1983. Works fine. They are connected to the internal floppy control connector on the control card, with a flat cable. Drive selection DS0 and DS1, terminating resistor pack in the drive at the physical end of the ribbon cable. Drilled some extra holes inside the box to mount them. Then I have two full-height IBM drives in the additional expansion box on top. They are also connected with a straight ribbon cable, using the rear external connector on the controller card. Drive selection is DS2 and DS3, again with the terminating resistor pack in the drive at the physical end of the ribbon cable. Controller card is a CorComp one, hence the ability to use four drives. The extra expansion box is my own. The power supply inside is also of my own design. Installed drives Extra expansion box Computer showing list of all drives available (those with a # in front) Sorry for the rreflection from the window. For you who never used the p-system; this is the list of all available I/O-devices in the system. Edited March 16, 2018 by apersson850 1 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted March 16, 2018 Share Posted March 16, 2018 As we are talking about many drives here, I still have a question. If I use 2 internal and 1 (or 2) external drives, the latter connected to this external edge connector, do I have to terminate 2 drives (the internal and the external latest drive on each cable/connector), or only that one that stays outside the PEB ? Maybe this means: Is there a "pass-through" from the controllers internal to the external connector ? thx Quote Link to comment Share on other sites More sharing options...
RickyDean Posted March 16, 2018 Share Posted March 16, 2018 As we are talking about many drives here, I still have a question. If I use 2 internal and 1 (or 2) external drives, the latter connected to this external edge connector, do I have to terminate 2 drives (the internal and the external latest drive on each cable/connector), or only that one that stays outside the PEB ? Maybe this means: Is there a "pass-through" from the controllers internal to the external connector ? thx Schmitzi, if there are three drives on one cable and one is external, the one at the end of the cable , be it external or internal, should be the terminated drive. That's the way I always understood it, anyways. 1 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted March 16, 2018 Share Posted March 16, 2018 yes, but what if I connect 2 drives with a cable to the "inside" connector of the TI´s FD-Controller, and 1 (or 2) drives to the 2nd, the external connector of the controller, with a seperate, 2nd, external cable ? thx Quote Link to comment Share on other sites More sharing options...
+Ksarul Posted March 16, 2018 Share Posted March 16, 2018 I think you have to terminate both if you do it that way, Schmitzi: in this case, you'd terminate the last drive on each chain. 2 Quote Link to comment Share on other sites More sharing options...
+Schmitzi Posted March 16, 2018 Share Posted March 16, 2018 I think that - if at least one external drive is used - ONLY the last external drive should be terminated. This means, that there must be a kind of "pass-through" between the internal and the external connector. THIS would also mean, that you cannot connect a Lotharek EMU-drive a a single external drive, nor as a single internal drive, as it cannot be terminated.... Exception: Lotharek as the lonely internal drive, with a present, terminated external drive. For having the Lotharek drive as the very only drive, maybe there is an "external terminator pack" available, like seen on SCSI, just to plug it to the end of the internal cable, the latest drive connector, or onto the external connector from the controller. But never saw something like this... From the manual: Quote Link to comment Share on other sites More sharing options...
marc.hull Posted March 16, 2018 Share Posted March 16, 2018 Good practice is to terminate the end of every cable. Some drives will work with to much or to little termination as will some FDC cards so the applicable acronym is YMMV. But in the end termination at the end of every cable (AKA bus) is a wise choice. Pretty much assures that functional devices work as advertised. 1 Quote Link to comment Share on other sites More sharing options...
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