

This is one of a few revisions of motherboard BIOS for the IBM 5170 (IBM AT).
This revision is dated 15NOV85 (11/15/85).
It is found in type 3 motherboards (type 3 runs at 8 MHz).


+---------------------------------+
|  GENERAL                        |
+---------------------------------+

ROM chip U27 has the IBM part number of 62X0820, and is 32K in size
ROM chip U47 has the IBM part number of 62X0821, and is 32K in size


8 bit checksum of 62X0820 = 04
8 bit checksum of 62X0821 = FC
                           ----
                    added = 00


+---------------------------------+
|  FILES                          |
+---------------------------------+

File BIOS_5170_15NOV85_U27_62X0820_27256.BIN is a binary image of ROM chip U27.  [ 32 KB in size ]
File BIOS_5170_15NOV85_U47_62X0821_27256.BIN is a binary image of ROM chip U47.  [ 32 KB in size ]


+---------------------------------+
|  USING FILES TO MAKE EPROMS     |
+---------------------------------+

1. Obtain two blank 27256, or 27C256, EPROM's rated at 250 ns (or less [faster]).

2. Burn file BIOS_5170_15NOV85_U27_62X0820_27256.BIN to the first 27256, then label the 27256 as "U27".

3. Burn file BIOS_5170_15NOV85_U47_62X0821_27256.BIN to the second 27256, then label the 27256 as "U47".





