What’s the deal with that 88-ACR documentation?

General discussions related to the Altair 8800 Clone

What’s the deal with that 88-ACR documentation?

Postby MajorClements » October 7th, 2022, 1:13 pm

If Jerry Seinfeld was into 8-Bit Microcomputers, I’d imagine that is what he’d probably ask on stage.

Jokes aside, I have been dealing with this head scratcher of a problem for a few weeks now. Last month, I decided to get back into the Altair 8800. I actually haven’t used my system since 2015. Now that I had some time to mature my knowledge of how computers fundamentally work, I wanted to takle my ultimate goal, program with the front panel! I probably would’ve done this a lot sooner, had I read the original manual from the mid-70s, as per Mike’s instructions in the build guide.

Anyway, I inputted a bunch of instructions into the system, mainly dealing with registers and memory reading and writing. For some reason, I assumed the clone had the ability to perform a memory dump, like being able to insert and take out floppy disks through the monitor. It was only after I had finished working on my experiments that I didn’t have an easy way of getting that data back. I tried looking for a program that could dump the contents through the serial port, but I couldn’t really find any information online. Instead, I consulted with the 88 – ACR manual, and I located exactly what I was looking for: two programs, one for saving and the other for loading through the cassette interface. Sadly, after I had attempted to write the write program and execute it, it rewrote my code over with a pattern, which I can’t recall what it was, though. Leaving it partially destroyed. Thankfully, I decided to copy down everything that I had written up to that point on paper.

Well, I tried everything to verify that I had entered the code correctly, I single stepped the program, and everything looked OK. When I did run the program that time, the output of the cassette interface did change to,
what I assume was, that pattern. Changing the address of the cassette interface in the write program did stop the output, so it is using the correct address. Maybe it doesn’t like how much code I have? I’m curious if anyone ran into similar problems? Honestly, I recall Mike saying that even the MITS documentation had mistakes too.
Sincerely,
Daniel
________________________________________________________________________________
“THINK!”
If you had to remember only one thing about me, just know that I’m the guy with too many ThinkPads to count.
MajorClements
 
Posts: 18
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Location: McLean, Virginia

Re: What’s the deal with that 88-ACR documentation?

Postby toml_12953 » October 7th, 2022, 5:09 pm

MajorClements wrote:If Jerry Seinfeld was into 8-Bit Microcomputers, I’d imagine that is what he’d probably ask on stage.

Jokes aside, I have been dealing with this head scratcher of a problem for a few weeks now. Last month, I decided to get back into the Altair 8800. I actually haven’t used my system since 2015. Now that I had some time to mature my knowledge of how computers fundamentally work, I wanted to takle my ultimate goal, program with the front panel! I probably would’ve done this a lot sooner, had I read the original manual from the mid-70s, as per Mike’s instructions in the build guide.

Anyway, I inputted a bunch of instructions into the system, mainly dealing with registers and memory reading and writing. For some reason, I assumed the clone had the ability to perform a memory dump, like being able to insert and take out floppy disks through the monitor. It was only after I had finished working on my experiments that I didn’t have an easy way of getting that data back. I tried looking for a program that could dump the contents through the serial port, but I couldn’t really find any information online. Instead, I consulted with the 88 – ACR manual, and I located exactly what I was looking for: two programs, one for saving and the other for loading through the cassette interface. Sadly, after I had attempted to write the write program and execute it, it rewrote my code over with a pattern, which I can’t recall what it was, though. Leaving it partially destroyed. Thankfully, I decided to copy down everything that I had written up to that point on paper.

Well, I tried everything to verify that I had entered the code correctly, I single stepped the program, and everything looked OK. When I did run the program that time, the output of the cassette interface did change to,
what I assume was, that pattern. Changing the address of the cassette interface in the write program did stop the output, so it is using the correct address. Maybe it doesn’t like how much code I have? I’m curious if anyone ran into similar problems? Honestly, I recall Mike saying that even the MITS documentation had mistakes too.


The ACR manual is correct. Did you enter the start and end addresses in low byte high byte order? The write program writes memory to cassette so it wouldn't affect a program in RAM. If you lost your program when you ran the write program, there was an error made in entering the program. The read program reads cassette and saves the input to RAM.
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Re: What’s the deal with that 88-ACR documentation?

Postby MajorClements » October 8th, 2022, 11:02 am

Hey toml_12953! That is what I figured. Evidently, I more than likely made a mistake. I wrote the write program at address 017000, as indicated in the manual. As for the start and end address, I chose 000000 to 000377. I probably flipped them. I don’t know what else it could be.

Well, I’ll give it another go sometime this weekend. I wanted to throw together a “clear memory” program in Assembly, so I will test it again and let you know.
Sincerely,
Daniel
________________________________________________________________________________
“THINK!”
If you had to remember only one thing about me, just know that I’m the guy with too many ThinkPads to count.
MajorClements
 
Posts: 18
Joined: January 30th, 2014, 9:18 am
Location: McLean, Virginia


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