While I am waiting for Apple 1 PCB to show up so I can begin my build, I decided to read the manual. In the manual is a test program written in 6502 machine lanuage.
So I decided to disassemble that code and turn it into readable 6502 assembly language. So for those of you who are interested in what the test program does or is looking to learn 6502 assembly language, here something to get you started.
AA9 00 LDA #$0 Load A (Accumulator) register with 0
AA TAX Transfer what is in the A register to the X Register. The contents of the A register are unaffected
20 EF FF JSR $FFEF This is the output character routine in the Apple 1 monitor. Let the monitor do the work for you
E8 INX Increment the X register
8A TXA Transfer the contents of the X register and put it in A register
4C 02 00 JMP $0002 Jump to the TAX instruction to get the Next Character and after we get to the last character the program starts over
All the instructions and numbers are in hexidecimal.
I hope this will peak your interest and you will want to learn 6502 assembly language.
If you have any questons, please ask.
This is good stuff, thank you. I am closer by the year to acutally understanding this :P
I know you mentioned you are building a Replica1 as well. If you have not already, the downloads for the Replica 1 also have good docmentation and some programs available http://www.brielcomputers.com/files/r1pluscd.zip
The KRUSADER assembler documentation may also be of interest to you, as it is in ROM on the Replica 1.
If you have questions along the way, particlarly with the Replica 1 or SD card from P-LAB, I'll have my eye on this forum and help if/when I can.
Glad you liked it :)
Thanks for your help! After looking at the docs for the Apple 1 Micro SD card, you have to disable all the built-in full RAM expansion. So I decided to build a full Apple 1 replica, so I can take full advantage of P-labs SD storage card.
There are no shortcomings of the P-LAB card on the Briel. Per Claudio, the jumper you are talking about:
"It disallocates RAM from 4000 to 7FFF from being handled by sdcard board, leaving it handled by Replica-1 builtin RAM."
The ram is still available to the user just handled differently. Claudio had me run some tests before also testing it himself I believe. Here is some info from our email exchange:
To be sure that everything is OK with RAM you could run the MEMORYTEST in UTILS folder.
It's the classic Willegal's RAM test:
This will test the entire RAM from 0500 to 7FFF.
Output on Briel Replica 1:
$0280-$03A1 (290 BYTES)
0:0 5 0 80
0280: A9PASS 01
regarding the microSD card you are both right.... :-)
Alex got the first version (1.13), which did not yet have RAM partitioning designed for Briel's Replica-1, in fact he had to make some "adjustments" by hand.
Bill will get version 1.18, that only needs the removal of the 3 jumpers to be compatible with the Replica-1:
It is all in the latest version of the docs:
@Bill: I've added a handwritten note to you in the package as a reminder, since you'll be using the card on both machines.