Some rights reserved! Vintage technology preserved.
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It's simple: vintage ibm pc booter games can be converted to boot rom image - eventually, just like in the following case. Had a little progress in the last year due to well-known reasons, so it's showtime again! Converted Boulder Dash ibm pc booter version to a 32k custom rom bios image. The steps were plausible: Original image ripped from one of my previous projects, see here: Booting from COM1 - part 2; and then splat into two parts: 200h (512) bytes of header and from beginning offset 700h to the end. Those ranges are loaded by a newly developed loader destination segment is a ram segment 1000h again as before. Before filling destination segment with data, it is initialised with zeroes. After linking, concatenating images, all 32k bytes inc. magic header must have 0 "checksum", which means mod 256 zero sum of all bytes ignoring overflow, carry, whatever. For the curious, this two^Woneliner could help determine what to add a byte to fix rom checksum errors:
$ od -v -t u1 boulder.rom \
| awk '{for(i=1;i++<NF;){a+=$i}a%=256}END{printf"%x\n",(256-a)%256}'
In case is someone would try this out, open an xterm, then invoke qemu with these options:
$ qemu-system-i386 -net none -option-rom boulder.rom
Bringing back memories from 1980s when playing nights with commodore 64
Here you are:
Reminder: use space in menue, player controls are arrows and left shift.
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