BillG wrote:
* Microsoft BASIC for the Altair 680
Unfortunately as fr I know there are no sources available. Making it run on my hardware will be tricky and above my skill I am affraid...
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* Robert Uiterwyk's 4K and 8K BASIC for the SWTPC 6800. I think the MicroBASIC you have is the 4K version. The source code for the 8K version may have been made available as well.
* Technical Systems Consultants (TSC) BASIC and Extended BASIC for FLEX
According to the info printed on screen at startup, In fact I am using TSC Basic. For some reason the place where I found it on line described it as a "MicroBasic".
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Microsoft may be the best bet for something ROMable.
There is no source code so I can neither relocate it to the EPROM address space nor provide my own I/O routines. I was only able to find assembled S19 files on-line, but they were made for some particular system.
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6800 code is not position independent. Did you assemble the code ORGed where it is to run or where it resides in ROM? I am surprised it got that far if the latter.
Yes. I assembled it with ORG statement set up for 0x0200. I generated S19 file and loaded it to RAM. Everything worked. Then I took the same file, converted it to intel hex with srec_cat, shifting entire blob of hex data to 0xD000. In the next step I used srec_cat to combine three hex files into one. So I have:
* Smithbug monitor (at address 0xC000)
* Short code for copying Basic interpreter from 0xD000 to 0x0200 (at address 0xC900)
* Basic interpreter (at address 0xD000)
After launching computer I am able to execute jump to 0xC900 and apparently it works, because while dissasembling memory content above 0x0200, I see proper instructions. Copied Basic executed from 0x0200 launches itself (I can see welcome message and prompt) but it is extremely unstable - usually it freezes or gets stuck in reset loop just when I start to type.