I have 8K BASIC running in my emulator at 0x0000, but I'd like to move it to 0x8000 to see if I could run it from flash instead of sram on a device I'm building. I've heard that it has some self modifying code, but I could probably find that by having the emulator trap when anything is attempted to be written above 0x8000. I'm not sure I could get this working, but I'm tempted to try it. My understanding is that there is no real source for Altair 8K BASIC out there. My question is, is there an 8080 relocator that could attempt this? Or perhaps a disassembler that can disassemble it if an assembler could produce the same binary from the disassembly. The goal here would be to move as much of it as possible to flash memory at 0x8000 leaving only was is needed in sram in sram to increase the free space in sram.
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Relocator for Altiar 8K BASIC
- Thread starter alank2
- Start date
Chuck(G)
25k Member
That depends. If it uses the RST x vectors, you need SRAM in low memory at least for those.
deramp5113
Veteran Member
Altair ROM BASIC executes from PROM instead of RAM like you're trying to do by moving Altair 8K BASIC. Altair's ROM BASIC is Extended BASIC and runs at C000h. See the two "Extended BASIC..." files here: https://deramp.com/downloads/altair/software/roms/orginal_roms/
Mike
Mike
deramp5113
Veteran Member
If anyone is interested, I modified the extended ROM basic 4.1 to:
Replace the underscore functionality with backspace. When you type backspace, it will backspace, space, backspace so that it is destructive.
I also enabled most of the version/copyright. (I replaced the " BY MITS INC." with the code that does the backspace, space.)
It now says:
MEMORY SIZE?
LINEPRINTER? O
ALTAIR ROM BASIC VER 4.1
COPYRIGHT 1977
The file is pure binary beginning at 0x0000:
View attachment Extended ROM BASIC 4.1 (BS).zip
Replace the underscore functionality with backspace. When you type backspace, it will backspace, space, backspace so that it is destructive.
I also enabled most of the version/copyright. (I replaced the " BY MITS INC." with the code that does the backspace, space.)
It now says:
MEMORY SIZE?
LINEPRINTER? O
ALTAIR ROM BASIC VER 4.1
COPYRIGHT 1977
The file is pure binary beginning at 0x0000:
View attachment Extended ROM BASIC 4.1 (BS).zip
deramp5113
Veteran Member
Sounds like a fun little project!
Mike
Mike