Bill Beech and and IDE/ATA drives on Multibus

Last edit Nov 14 2011 (c) Herb Johnson


[Bill Beech NJ7P contacted me in June 2009 to exchange manuals and resources about our Intel System 310 Multibus systems. We've talked about a number of Multibus 8080 and 8088 subjects. See the linked Web for links to all those activities, and about Bill and his other work on the Web.

In the fall of 2011, Bill is working on an Intel 80/10 CPU board and related Multibus boards, to get a CP/M system in operation. After getting most of the kinks out of a floppy based CP/M-80, he's now working on operating an IDE (lately called ATA or PATA) hard drive to operate. That's the topic of this Web page. - Herb

floppy and CP/M-80 2.2

Note: Bill's work on the floppy controller and CP/M is described with his Intel 80/10 work on that Web page. That work is necessary and preliminary to adapting an IDE drive to CP/M. - Herb

Maybe I need to put more of the current software and some of the debug runs on [my Web site] you to look at. Also, maybe more pictures. I have also got a write up about bringing up the iSBC 80/10, that's better than the original journal that is currently on my web site.

I am now debugging the BIOS write routines, which are failing. The iSBC 208 driver write works solid. So it is internal to BIOS. The BIOS deblocking read is working correctly.

[At this Web link] is a debug run from today. First load is CPM80, then SYSGEN to load it onto the floppy and format the directory entries, then I load BOOT and run it. My boot routine in the ROM still needs work. You see the FDC interrupt messages and a lot of BIOS debugging as it happens. Once CCP is called, then the directory of drive A is read in. You see 4 cpm sectors being handled per one host sector (512B).

IDE drive

The 8255 interface off-card on the iSBC 80/10, and on the iSBX 350, is a 50-pin card edge connector. I am using an 8-inch floppy cable to convert that to a 50-pin connector on a proto-board. I'll mount that and a 40-pin IDE connector to build the adapter I discussed previously. Basically, I'm connecting the 8255 to the IDE HD using standard 8-inch floppy and IDE cables.

later:I built the scrambler for the IDE and did write version 1.0 of the IDE disk exerciser. Debugging it as it is a stand alone port of the CPM80 version used on the N8VEM. I am using modern IDE drives, and using the ATA-3 implementation of the interface. LBA all the way.

Not long after...: "The IDE drive is working correctly off the 8255 on the iSBC 80/10 board. I get the identity sector and am able to read and write random sectors to the hd with the hd exerciser. Now back to debugging BIOS write...

[Meanwhile it] looks like the FDC is reading and writing correctly. Now to play with format on it a bit, integrate the low-level IDE routines into the monitor ROM, and add IDE support to the BIOS. Then I will look at the BDOS [sources] and see where some 20- or 24-bit math would increase the maximum disk size to the 512 MB of CPM 3.0 . CPM3 seems like a hassle to run on a basic system and the old 2.2 was reliable and fairly small.

Contact information:

Herb Johnson
New Jersey, USA
To email @ me, see see my ordering Web page.

Copyright © 2011 Herb Johnson