Hi John
The problem is the data does not stay valid long enough after pWR* goes high. It is discussed on pages 335-337 of book. Also the 8255 requires the data be valid at least 30 nsecs after write signal goes high. The same type of issues occur on propeller and IDE select on the IDE board. Substituting F logic fixes those but the timing restriction on the 8255 is not reliable. I may try an Oki 8255 and see if it is better. The symptom is basically you can never set a sector so the read sector always returns the same data.
Dave
Sent from my iPad
Never did gate back to that 68K board Dave. For what it is worth the board works fine for me with the (unmodified) propeller Console I/O board, serial board, SMB and parallel ports I/O board. I have not checked it out with my IDE board mainly because I have no software written. If you have 68K MYIDE equivalent code written I can check it out here with either a 6MHz 68K or 68010. At one point I considered doing a 68030 or 68040 (like our 80386 etc.), but the lack of software/OS really makes it dubious as to use. I must confess I never did dig into how Wilcox arranged the state machine/support chips. Do you know what exactly is the problem. Is there a workaround. Should we contact Wilcox directly? John From: yoda [mailto:yo...@r2d2.org]
Sent: Saturday, January 31, 2015 2:15 PM
To: n8vem...@googlegroups.com
Cc: mon...@vitasoft.org
Subject: Re: [N8VEM-S100:6153] 68000/68010 CPU board Hi John It is not the speed of the processor - it is the state machine timing. I believe Pontius (spelling?) walked through the state machine and proved the timing is independent of processor speed so until the timing in the S100 state machine if fixed or the IDE board sensitivity, it is pointless to proceed as I have never gotten it to work with the 68K board. In fact I had to add some additional F series chips to get it working with the propeller board as well to get the IDE board to switch drives. The 68K board works ok but is somewhat limited use when you can't reliably do I/O to S100 peripherals. Wilcox pointed out the problems in his book but never gave a reliable solution. Dave
On Saturday, January 31, 2015 at 11:19:28 AM UTC-6, monahanz wrote: The issue Rick is the current board while quite reliable at about 6MHz, has problems going to higher speeds. There also MAY be a problem accessing the 8255 on the IDE/CF card. I think it was Dave Fry that noticed this.( I may have the wrong person). Anyway we are so busy these days you may be best to place a small order yourself for the original board. The kiCAD files are at the bottom of this page:- http://s100computers.com/My%20System%20Pages/68000%20Board/68K%20CPU%20Board.htm John Are we anywhere closer to ordering the 68000/68010 CPU boards? I would like to add my name to your list for 2 of them. I have been collecting ICs to build one, and I really want to get started this year. I already have several flavors of 68000 (68000P8, 68HC000P-12), and a 68010P10. --
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