Trying to load a 1024 byte PROM

General discussions related to the Altair 8800 Clone

Trying to load a 1024 byte PROM

Postby Jethro82 » April 12th, 2020, 12:55 pm

I'm trying to recreate the Tape punching program that punches out a string of entered ASCII Characters that was created in the video. I have 8 byte images for each of the 96 non-control ASCII characters and the code to drive it, I decided to total it at a round 1024 bytes, since I don't know how big my code would be but figured it would definitely be less than that, and I wanted an exact address for my data block in the code. I try to load it by XModem, and sometimes there's a progress bar and sometimes there isn't. When I just send file I pretty consistently upload 256 bytes. When I try to load it by XModem I get all kinds of sizes, most often 0 and it just doesn't take. I did get 400h bytes once, but there was an error in the code and I haven't been able to upload it since to see if I've corrected it.

I've also tried a front panel program to dump the 1024 bytes into memory along with the sent file. This is my listing for that:
Code: Select all
0 in 21      333 021
2 lxi h,1000h   041 000 020
5 In 20      333 020
7 ANI 1      346 001
11 JZ 5      312 005 000
14 IN 21   333 021
16 MOV M,A   167
17 INX H   043
20 MVI A,14h   076 024
22 CMP H   274
23 JNZ 5   302 005 000
26 JMP 100   303 100 000
100 JMP 100   303 100 000


It never completes and also seems to cops out at 256 bytes, when I stop and enter a character through the terminal it writes the terminal character to 1100h, and the next to 1101h. Not sure how to upload my binary to this forum, if people think that would help.
Jethro82
 
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Re: Trying to load a 1024 byte PROM

Postby AltairClone » April 13th, 2020, 1:40 pm

I'm not sure I quite follow what you're trying to do when you say "I try to load it by XModem."

It appears you are trying to write a program that runs on the bare machine (i.e., no operating system). In that case, there is nothing in an Altair that's going to accept any sort of data transfer for you (e.g., XMODEM). In this case you can "cheat" and use the binary or hex file load option in the Altair Clone's configuration monitor, or you can write a binary loader like you've done and run it from the front panel. Your binary loader program looks fine to me. I assume you're doing a simple file send and not an XMODEM send to this loader, right?

Mike
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Re: Trying to load a 1024 byte PROM

Postby Jethro82 » April 13th, 2020, 5:41 pm

Since the 'send file' wasn't working for me while trying to create a PROM, I uploaded the binary a couple times through the PROM menu with X-Modem. I only used the send file function with the front panel code, true. I figured it out in the end that's a a teraterm problem. The first 256 bytes were loading correctly, so I just divided my binary into 4 parts, each of which uploaded correctly, and whose output seems to be correct(I don't have a teletype so I just logged the bytes and then poked them onto a monochrome VGA screen.). So my problem is basically solved. It would still be good to know how to modify tera term to send larger files, though.
Jethro82
 
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Re: Trying to load a 1024 byte PROM

Postby AltairClone » April 14th, 2020, 11:12 am

I'm still confused about what is happening for you. Teraterm does not limit the size of the file transferred with the "Send" option, so something else is wrong. Be sure both hardware and software handshaking are OFF in the Setup->Serial Port menu.

Also, the PROM upload option in the Configuration Monitor should be a simple file send, not XMODEM. Like it says in the manual, "initiate simple send file operation from the PC – not XMODEM." If you send an XMODEM packet, then the 1st packet sent by XMODEM is being stored, not just the binary data you want.

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Re: Trying to load a 1024 byte PROM

Postby Jethro82 » April 14th, 2020, 8:58 pm

I don't know what happened either, I think it has to do with the large block of nulls at the end of my code followed by eight nulls for the space character. I changed the last code byte to an FF and the full 1024 bytes loaded no problem. So maybe with all the nulls the terminal thought the file was over and had been mis-sized on the drive? Anyway I have it now as a single disabled PROM, which (after testing, which I've done) was what I wanted.
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