From [http://minuszerodegrees.net/bios/BIOS_5170_10JAN84_6MHZ/README.TXT](http://minuszerodegrees.net/bios/): This is the first BIOS for the IBM 5170. It is dated 10JAN84. It is found in type 1 motherboards running at 6 Mhz. U27 has the IBM part number of 6181028, and is 32K in size U47 has the IBM part number of 6181029, and is 32K in size 8 bit checksum of 6181028 = 36 8 bit checksum of 6181029 = CA -- added = 00 There are two BIN files in this ZIP file: 1. BIOS_5170_10JAN84_U27_6181028_27256_6MHZ.BIN --> Use this to create a U27 using a 27256 EPROM (rated at 150nS or faster) 2. BIOS_5170_10JAN84_U47_6181029_27256_6MHZ.BIN --> Use this to create a U47 using a 27256 EPROM (rated at 150nS or faster) The JSON-encoded ROM image that PCjs uses was created using the *FileDump* command-line *merge* option: filedump --file=http://static.pcjs.org/devices/pc/bios/5170/BIOS_5170_10JAN84_U27_6181028_27256_6MHZ.BIN --merge=http://static.pcjs.org/devices/pc/bios/5170/BIOS_5170_10JAN84_U47_6181029_27256_6MHZ.BIN --output=1984-01-10.json --overwrite Since a MAP file ([1984-01-10.map]()) exists as well, it is automatically appended to the JSON file ([1984-01-10.json]()) when using a ROM input file (or JSON output file) with a matching filename. It is also possible to create a merged binary ROM image ([1984-01-10.rom](http://static.pcjs.org/devices/pc/bios/5170/1984-01-10.rom)) by adding *--format=rom* to the command-line (the default is *--format=json*). These operations can only be performed using the *FileDump* command-line interface; the *FileDump* API does not support either the *merge* option or the appending of MAP data. For the moment, the API can only dump unadorned ROM images; eg: http://www.pcjs.org/api/v1/dump/?file=http://static.pcjs.org/devices/pc/bios/5170/1984-01-10.rom