Hi Josh,
Thanks for answering my questions as I know you are busy getting
ready for VCF-MW (along with everyday responsibilities). I am currently
using the 8080 board in my test bench setup which consists of an N8VEM
S-100 backplane, and an IMSAI front panel. The mask and plexiglass were
damaged so I removed them and am using the front panel bare until I
restore the machine it is going in. I hope to take some photos tomorrow
as you had said a few weeks ago that pictures would be nice.
I wound up using a 2GB Transcend Digital card formatted as FAT16.
Thank you for describing the boot process in detail. I may try loading
a CP/M image from another source like an emulator since the boot ROM
will not load the bios off the disk. One question I can think of is
that most the the emulators I have seen use the .DSK format for images
while you are using .BIN images. Do you know what the differences are
between the 2 formats?
Thanks for providing some syntax for the XMODEM & RAM test commands.
I now realize that I should have looked more closely at your monitor
listing as it was all described there. I will try to use the XMODEM
command to transfer some files and see how I make out. BTW, I do like
how you make use of the front panel output port LED's to act at a
progress indicator. Now I can also use the RAM test to test some
external boards I have by disabling blocks of onboard memory and
addressing the external boards in that address space.. Great! Thanks for
all your help!
Regards,
Jeff
On 9/1/2014 7:42 PM, Crusty OMO wrote:
Jeff,
Excellent! I'm really happy to hear your enjoyment in building this
card. I'm curious, what front panel are you using to operate the board?
I would really like to know which card(s) work for you.
The ROM is designed so the CP/M BIOS loads at a specific location.
Here's what the memory looks like when you boot to the welcome screen.
DA00: Code for Welcome Screen (3 choices)
Dxxx: Code for the Monitor (uses routines in BIOS)
EE00: CP/M BIOS
Now, when you load CP/M, a jump to the cold boot at EE00 causes the
first XX number of sectors to be loaded from the file in "Disk-A" at
DA00, so the memory now looks like this:
DA00: CP/M (CCP and BDOS)
EE00: CP/M BIOS (as loaded from Boot ROM, NOT from Disk-A).
So, you can have some other CP/M bios on "DISK-A" at sector XX+1, my
ROM will not load that other BIOS, because my ROM should have all the
BIOS you'll ever need for CP/M.
Now, back to loading files.... the only way I can think of doing it
with what's there is....
1. Boot system to Monitor
2. Transfer a file to Memory.
You can do this with XMODEM. from the Monitor, type:
X U 100 <Enter>
Then start an XMODEM transfer from your terminal program.
Step 3. You can either reset and boot to CP/M or from the monitor,
type G DA00 to Jump to DA00 (the CP/M cold boot).
Step 4. Rich Cini describes this CP/M instruction very well in his
paper, I hope I don't mess it up here...
The program you loaded at 0x100 is still there.
At the a> prompt, type
SAVE 10 filename.ext
This will write 10 pages of 256 bytes from 0x100 to the file name you
specify.
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