Matching the data read from virtual 2315 image file to the 1130 disk file - more validation of the functionality

DISK FILE FORMATS FOR USE WITH THE VIRTUAL 2315 CARTRIDGE FACILITY

The IBM 1130 Simulator(s) use a version of the simh disk format which stores each word as two bytes in little endian 8086 format. Each sector is 321 words of 16 bits on the 1130, thus 642 bytes in the disk file. These are stored sequentially in the file, sectors 0 to 3 within each of the two heads, within the 203 cylinders. Thus cylinder 1, head 0 sector 0 begins at byte 5,135 in the file. The entire file is 1,042,608 bytes in size.

The Virtual 2315 Cartridge Facility has a header with information about the cartridge followed by the data in big-endian format. The data is sector 0 to 3, within heads 0 to 1, within cylinders 0 to 203. The header is 365 bytes long and the entire file is 1,042,973 bytes in size. Thus, cylinder 1, head 0, sector 0 begins at byte 5500 in this type of file. 

FINDING THE SECTOR DATA FOR CYL 10, HEAD 1, SECTOR 2

Opening the IBM 1130 Simulator format disk file, I calculated the start location for Cylinder 10, Head 1, Sector 2 which is the data I emitted in the debug log when testing the system. This starts at byte 55,212 which is hex 0xD9A0. Below is a hex editor showing the contents of locations 0xD9A0 to 0xDA2D so that we can compare it to the debug log. 

THE DATA MATCHES UP

The only conversion needed when comparing these is to swap the two bytes of each word in the sector, since the file I dumped is in little-endian integer mode while the Virtual 2315 Cartridge Facility implements big-endian integers as does the IBM 1130 hardware. 

The first two words from the dump are 5600 and 2461. The debug log shows these are 0056 and 6124. The final word of the dump is 204C and the final word from the debug log is 4C20.