The earliest versions of the HP 3456A voltmeter used six 32k bit program ROMs.  Later 
versions had only three 64k bit parts: U5, U7 and U8.

The final production versions used a single 256k bit program ROM:
HP Part Number: 03456-65501
Date Code: 9002
Type: TMS27PC256NL 
Checksum (lower 4 digits only): 9BE9
ROM Size: 32k Bytes (256k bits)
Memory Map:
     0000-1FFF = all FF data value (unprogrammed)
     2000-3FFF = the same data as U5 in the three chip ROM version
     4000-5FFF = the same data as U7 in the three chip ROM version
     6000-7FFF = the same data as U8 in the three chip ROM version


Included in this package are:
========================
readme.txt          this file

27c256.bin          raw binary file of 256k bit ROM (checksum = 9BE9)
27c256Intel.hex     Intel hex file of 256k bit ROM (checksum = 9BE9)

U5.bin              raw binary file of 64k bit ROM U5 (checksum = 9CF5)
U5Intel.hex         Intel hex file of 64k bit ROM U5 (checksum = 9CF5)

U7.bin              raw binary file of 64k bit ROM U7 (checksum = D212)
U7Intel.hex         Intel hex file of 64k bit ROM U7 (checksum = D212)

U8.bin              raw binary file of 64k bit ROM U8 (checksum = 4CE2)
U8Intel.hex         Intel hex file of 64k bit ROM U8 (checksum = 4CE2)
