pritch@osu-eddie.UUCP (Norman Pritchett) (06/22/86)
I have been under the impression that the floppy controller for the Color Computer (the one sold with the slim-line drives if it makes a difference) supported 4 single-sided drives. After adding my fourth drive I found that it wouldn't select the 4th drive but it would select the second side of my double-sided drives. Have my impressions been mistaken? Do I max at three drives and get double-sided support or am I supposed to get four drives and something isn't working? -- Norm Pritchett, The Ohio State University BITNET: TS1703 at OHSTVMA Bellnet: (614) 422-0885 UUCP: cbosgd!osu-eddie!pritch CSNET: pritch@ohio-state ARPANET: NPRITCHETT%osu-20@ohio-state (or) pritch@ohio-state
dml@loral.UUCP (Dave Lewis) (06/25/86)
In article <1970@osu-eddie.UUCP> pritch@osu-eddie.UUCP (Norman Pritchett) writes: >I have been under the impression that the floppy controller for the Color >Computer (the one sold with the slim-line drives if it makes a difference) >supported 4 single-sided drives. After adding my fourth drive I found that >it wouldn't select the 4th drive but it would select the second side of my >double-sided drives. > Norm Pritchett, The Ohio State University Radio Shack did a funny thing when they made that controller. They used the first 3 drive select lines on the bus, then connected the /D3 select line to the side select. If you buy your disk cables from Radio Shack you find that they've connected each of these four lines, in turn, to the /D0 select line on one connector. All the drives are jumpered as drive 0, and the drive on the first connector actually responds to the /D0 select. They want you to buy THEIR cables you see (at $30 a shot too). Actually, you're better off with three double-sided drives anyway (3 * 2 == 6, 4 * 1 == 4) IF both your drives and your software will support it. None of Radio Shack's standard software, including OS-9, will support double sided disks. While I will readily agree that they picked a strange way to handle the thing it does make it simpler to rewrite their software for double sided drives. ------------------------------- Dave Lewis Loral Instrumentation San Diego sdcsvax--\ gould9 --\ ihnp4 ---->-->!sdcc3 ---->--->!loral!dml (uucp) sdcrdcf -/ crash ---/ "...got the most in you and use the least. Got a million in you and spend pennies. Got a genius in you and think crazies. Got a heart in you and feel empties." -------------------------------
jimomura@lsuc.UUCP (Jim Omura) (06/27/86)
In article <1970@osu-eddie.UUCP> pritch@osu-eddie.UUCP (Norman Pritchett) writes: >I have been under the impression that the floppy controller for the Color >Computer (the one sold with the slim-line drives if it makes a difference) >supported 4 single-sided drives. After adding my fourth drive I found that >it wouldn't select the 4th drive but it would select the second side of my >double-sided drives. > >Have my impressions been mistaken? Do I max at three drives and get >double-sided support or am I supposed to get four drives and something isn't >working? > >-- No, you aren't mistaken. You can use 4 single sided drives or you can use 3 double sided. But as you have noticed, the standard side select line is used to select drive 4 on the single sided RS drives. You can even mix single and double sided, as long as you don't use the last drive position for anything but side select. -- James Omura, Barrister & Solicitor, Toronto ihnp4!utzoo!lsuc!jimomura Byte Information eXchange: jimomura (416) 652-3880
mikey@bbimg.UUCP (07/02/86)
The problem was that back in the late 70's, when the Model I was first coming out, Tandy wanted to be able to have 4 drives, the there were only 3 selects. The line they picked for the 4th select later was defined as the side select. They get around the problem in the Model 3/4 by using only 2 selects. The internal drives are selected as 0 and 1, and the external drives are selected as 0 and 1 on a totally different cable! Unfortunately, Tandy didn't put in the pin in the cable on the early 3s and 4s for the side select signal. Tandy uses all drives selected as all drives. The cable has pins installed for drive 0 only on the slot for drive 0. This makes it easy for the usually non-technical customer. The only difference that customer must concern himself with is one drive should have a terminator pack. BTW, if you want to put DS drives on a 3/4, just flip over the cable and then jumper the drives for 0 and 1 on the drives. The other side is just grounds and can stand a few missing pins. I'll bet the problem with the drive 4 select vs side select is you are using an aftermarket supplier of drives. (Maybe the new Tandy drives are standard, as I think the cable with the disk cartridge now only comes with two slots, and the 4 slot cable must be ordered from NP) Mike Yetsko trsvax!techsup!bbimg!mikey