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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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