8-bit IDE

please see embedded comments below. Dick ----- Original Message ----- From: allisonp &lt;allisonp(a)world.std.comTo: &lt;classiccmp(a)classiccmp.orgSent: Sunday, April 16, 2000 6:44 PM Subject: Re: 8-bit IDE be CP/M3. The really good thing about the latchless and bufferless interface to the 8-bit channel is also readily adaptable to a RAMDISK via the same channel. That's what makes me hope for the availability of the 8-bit mode as described in the ATA standard. Using LBA, it's possible to write a 24-bit sector address to a RAMDISK. An old 8-bit SIMM would do the job nicely. I'm not fired up about these various OS' (yet) and won't be until I'm sure I know how to exploit their features. In any case, in a system where I've got 2 floppies, a dummy FDD, and a ramdisk, I can only use 12 logical drives at a time, since the max is 16, which, if it were all in HDD's would be 96 MB. Since it appears to be the consensus that all the doc's + all the software and such for CP/M 2.2 and earlier, take up less than 50 MB, a big drive in excess of 120 MB would make no sense at all. The Walnut creek CD has only about 1/5 of its capacity used. So, while it may be possible with a lot of effort and with the certainty that you'll be out there all by yourself, to use a bigger drive, what's the point? I mentioned I had a 44MB drive back in the '80's and even though I had several copies of everything, it was never even close to half full. So, while I don't doubt that someone could figure out a way to use a bigger drive rationally, I don't feel motivated to go out of my way. If the pico-drives I already have will work in 8-bit mode, then the code I already have will work to operate them. If not, I'll build up a circuit equivalent to the Tilmann Reh GIDE interface, less RTC. It's less RTC because I have a different RTC device if I ever want to use one. The two 2-1/2" IDE drives I've got for this hard-card thing are both 250 MB, nominally. If you have a good and inobtrusive way to accomodate that without reducing the size of the TPA to such extent that I can't run a normal 64K CP/M and such that I can still use the MT+ v5.5 or so Pascal compiler for serious work, I'd be interested. I've also got a couple of 2-1/2" (IBM)drives with a 2mm-pin pitch connector with enough pins to be a SCSI device. I don't know what their pinout is likely to be. I'll have to look in the standards, since IBM doesn't have them on their site. These are 120 MB in size. The standard v2.2 CP/M doesn't like logical drives (partitions) bigger than 64K 128-byte sectors. That's 8192 KB. What I'm after is something that will paste easily into a pretty standard CP/M 2.2. All the other whatever-dos will have to be denonstrated working properly and properly documented as well before I'll be interested. > >handle that much. Back when I used CP/M every day, I owned the largest > hard > >disk system on CP/M that I'd ever seen, at 44MB. > Obviously you've never seen many of the systems I ran or have aquired. > Likely > the 44mb limit was based on inavailability of really large drives. Even my > AmproLB has a 45mb SCSI on it and I plan to bump that up to a 160mb. The > current system I'm building I'm planning will have IDE 250mb drive. Space > is handy as I can have a 8mb partition for pascal and another for C or > whatever. You're right, I haven't seen the systems of the type you describe. That's because I switched to PC's in about '84. Most of the hard disks I saw in commercial use with CP/M were about 20 MB. These were sufficient. Apparently that was a practica size for DEC machines of the time too, since most of my partner's DEC clients had 11's of some sort, mostly with single 20 MB drives. <snip> Allison