procedure main()

	header := reads(&input, 512)
	emptyblock := repl(char(16r6d)||char(16rb6), 256)

	type := ord(header[16r200])
	write(&errout, "type is ", type)
	case type of {
		3:	{ write(&errout, "EPS (DD) format")
			  offset := 16ra0 }
		16rcb:  { write(&errout, "ASR-10 HD format")
			  offset := 16r60 }
		16rcc:  { write(&errout, "TS-10/12 HD format")
			  offset := 16r60 }
		7:	{ write(&errout, "TS-10/12 DD format")
			  offset := 16ra0 }
		default:
			stop(&errout, "Unknown format")
	}

	blocknum := 0
	offset +:= 1
	map := ord(header[offset])
	bit := 16r80

	repeat {
		if iand(map, bit) = 0 then {
			if block := reads(&input, 512) then 
				writes(block)
			else
				break
		} else
			writes(emptyblock)

		bit /:= 2
		if bit = 0 then {
			offset +:= 1
			map := ord(header[offset])
			bit := 16r80
		}
		blocknum +:= 1
	}

	write(&errout, blocknum, " Blocks")

end