Gotcha. In fact, the buffer fill byte was FF so that was it. 

Sent from my iPhone

> On Dec 21, 2014, at 3:27 PM, John Monahan <[email protected]> wrote:
> 
> Again traveling David, so going on memory. You will see that the MemoryMap 
> routine in either the Z80,8086 or 80386 monitors simply looks to see if the 
> RAM area is a 0FFH if so it’s assumed to be non RAM or non ROM area.  So if 
> FF happens to be at an 100H boundary then it would be flagged as a RAM hole.  
> The test could be clearly more extensive such as looking at surrounding bytes 
> (or words).  However the original code was for a Z80 ROM where space is 
> limited.   The test simply see if the address is 0FFH,  If not can the byte 
> be inverted if RAM if not ROM!  Some day I will add more tests for the 80386 
> monitor
> John
>  
>  
> From: [email protected] [mailto:[email protected]] On 
> Behalf Of Richard Cini
> Sent: Sunday, December 21, 2014 2:28 PM
> To: S100-Post
> Subject: Re: [N8VEM-S100:5874] Re: S100 Board anomalies
>  
> David —
>  
>               Thanks for the tips. I will look at the ROM later today. That’s 
> probably it since it works fine.
>  
>               On the RTC, that’s an interesting thread. I guess it makes 
> sense to ship the chip essentially “off”. I’ll have to look at the time 
> setting code in the 8086 monitor, though, to see if it actually enables the 
> clock or not. Otherwise I’ll grab the z-rtc program and give that a try.
>  
> Thanks!
>  
> Rich
>  
> --
> Rich Cini
> Collector of Classic Computers
> Build Master and lead engineer, Altair32 Emulator
> http://www.classiccmp.org/cini
> http://www.classiccmp.org/altair32
>  
> From: David Fry <[email protected]>
> Reply-To: S100-Post <[email protected]>
> Date: Sunday, December 21, 2014 at 3:46 AM
> To: S100-Post <[email protected]>
> Subject: [N8VEM-S100:5874] Re: S100 Board anomalies
>  
> Hi Rich,
>  
> I can probably answer two of your problems,
> the memory map showing a '.' in the prom area is probably where the memory 
> map routine samples a memory value and the value sampled turns out to be FFH, 
> I've just completed my 80386 board and have been chasing my tail all last 
> evening on the same issue where that also prints two '.'s in the prom area.
>  
> Open your  Z80 v4.8 monitor in your programmer software or hex editor and 
> look at memory location 0F00H which would correspond to EF00H in your memory 
> map,
> I guessing it will be an FFH. you can confirm this behaviour by examining the 
> monitor code for memory map generation.
> I use Z80 monitor version 5.02 and that one displays the memory map fine as 
> it doesnt contain FFH in the sampled locations.
>  
> With regard to your Real Time clock not working, the RTC chips are shipped 
> with the internal register set to stop clock, view the following thread, 
> particularly Gary's last post to figure out how to start the clock
>  
> https://groups.google.com/forum/?fromgroups#!searchin/n8vem-s100/ds12885/n8vem-s100/Ba5_Gwva170/H6AD-JOSQXgJ
>  
>  
> hope this helps
>  
> David Fry
> On Sunday, December 21, 2014 2:56:14 AM UTC, AltairManRich wrote:
> All —
>  
> I was playing around, again, with my Z80/8088/PropIO/4MB/PC-AT board set and 
> I still really can’t get it working properly. I have gone over the boards and 
> I’m pretty sure that there aren’t any soldering issues. I’ve also re-flashed 
> the ROMs just in case. Z80 version is 4.8. 8086 version is 10.33a. I will say 
> that I’ve never had a problem with the Z80 board in my old configuration of a 
> legacy 8-bit serial card and CompuPro 64k RAM board.
>  
> Here are some of the oddities I’m seeing:
> When doing a memory map from the Z80, the ROM is shown as all “p” except for 
> the xxFx address which is a “.”. For RAM, it does show “R”. It doesn’t matter 
> where I locate the ROM. So…
> D000 R R R R R R R R R R R R R R R R
> E000 p p p p p p p p p p p p p p p .
> F000 R R R R R R R R R R R R R R R R
> In the 8086 monitor, if I use the “R” command, it goes into lala land when 
> printing the flags, printing a continuous stream of “0” after half of the 
> flags are printed
> In the 8086 monitor, if I use the “A” memory map command, I get something 
> that looks like a map, but I get addresses like 00000,00000,80000,C0000 and 
> then each line is a mix of R and p. Finally it goes into lala land at the 
> end, continuously printing spaces.
> The RTC on the MSDOS board will not store the date/time and it returns 
> garbage when using the monitor commands which read them. I’ve swapped the 
> chip and the battery is installed. As an example time “25:06:00” and date 
> "20<7/26/14”. It appears that the clock isn’t running and can’t be set.
> I reduced the system to the PropIO, 4mb RAM and Z80 card so I could test the 
> RAM (at least the first 1mb) using a combination of the N and J commands. It 
> reported bad memory in each segment in the E000-EFFF range. This corresponds 
> to where my monitor resides in the first 64k, so maybe this is expected 
> behavior. No other memory errors were reported. I’d have to say that the 
> first 1MB is probably OK
>  
> So that leaves the 8088 or MSDOS boards as being the problem. Since the 
> monitor anomalies occur without the MSDOS board, it has to be a problem with 
> the CPU card.
>  
> John, by chance do you have one of the 8086 cards for sale?  Maybe I’ll start 
> from scratch using the 8086 card.
>  
> Rich
>  
> --
> Rich Cini
> Collector of Classic Computers
> Build Master and lead engineer, Altair32 Emulator
> http://www.classiccmp.org/cini
> http://www.classiccmp.org/altair32
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