Okay thanks.
I'll be working strictly with uncompressed ROMs.

There's something strange going on with a couple of Award V4.50 386 BIOSes I downloaded. I cannot open them with modbin as it claims there is a file checksum error.
However, the ROM checksum seems to be correct. Apparently Award BIOSes that have been opened with awdbedit exhibit the same problem. Anyone know what the deal is there?
Is there already a thread about this problem, or should I start a new one?

Have any of you looked at HDD translation/autodetection for the 64k AMI BIOS versions?

I don't know how late the 64k AMI BIOSes were used on a given board. If any of them received an update for larger drive translation or an update to the autodetect function courtesy of AMI and a generous board manufacturer, a byte comparison between an older version to the newer version may help zero-in on the replacement code. From there, you'd have to update any jump addresses for the BIOS you want to update - unless AMI BIOSes followed a standard layout/address structure, I suppose.

I am just spitballing. Not new to hex editors or assembly, but the contents of an AMI BIOS? My knowledge is maybe a couple of days old.

Totally possible that there is a hard cut-off date from moving from 64k uncompressed to LHA'ed 128k (or whatever it is) in order for AMI to even consider updating their drive calculations.

CkRtech wrote on 2025-05-02, 04:16:

Have any of you looked at HDD translation/autodetection for the 64k AMI BIOS versions? […]
Show full quote

Have any of you looked at HDD translation/autodetection for the 64k AMI BIOS versions?

I don't know how late the 64k AMI BIOSes were used on a given board. If any of them received an update for larger drive translation or an update to the autodetect function courtesy of AMI and a generous board manufacturer, a byte comparison between an older version to the newer version may help zero-in on the replacement code. From there, you'd have to update any jump addresses for the BIOS you want to update - unless AMI BIOSes followed a standard layout/address structure, I suppose.

I am just spitballing. Not new to hex editors or assembly, but the contents of an AMI BIOS? My knowledge is maybe a couple of days old.

Totally possible that there is a hard cut-off date from moving from 64k uncompressed to LHA'ed 128k (or whatever it is) in order for AMI to even consider updating their drive calculations.

Yes, I have thought of this 😁
Here, the 10/16/94 one here does not have LBA, and the 01/09/95 one does: https://theretroweb.com/motherboards/s/efa-4dmu-hl3s#bios
But, everything is shifted around, they didn't just simply patch in the LBA support, unfortunately.

jakethompson1 wrote on 2025-05-02, 04:20:

Here, the 10/16/94 one here does not have LBA, and the 01/09/95 one does: https://theretroweb.com/motherboards/s/efa-4dmu-hl3s#bios
But, everything is shifted around, they didn't just simply patch in the LBA support, unfortunately.

Yuck. Looks like they reclaimed some space above the $8000 BIOS copyright info and from the big block of $00 @ $DD42-$DFB1 and used it for some serious rewrite/replace under the BootSector Write/Possible Virus warning.

Anonymous Coward wrote on 2024-07-19, 02:35:

Okay thanks. I'll be working strictly with uncompressed ROMs. […]
Show full quote

Okay thanks.
I'll be working strictly with uncompressed ROMs.

There's something strange going on with a couple of Award V4.50 386 BIOSes I downloaded. I cannot open them with modbin as it claims there is a file checksum error.
However, the ROM checksum seems to be correct. Apparently Award BIOSes that have been opened with awdbedit exhibit the same problem. Anyone know what the deal is there?
Is there already a thread about this problem, or should I start a new one?

That should read 'open and saved with awdbedit'. This is an issue I've known about for some time. Best to do all modding with Modbin rather than awdbedit, although awdbedit has that convenient PCI routing table open for editing and the ability to swap the Energy Star logo.

On another front, has anyone had success in adding PS/2 mouse support to old Phoenix BIOSes? I have one from 1994, rev. 4.03c which doesn't work with a KBC-PS/2 mouse mod. It's an ALi 1429 board - EXP4349.

Anonymous Coward wrote on 2024-07-16, 14:24:

I'm not much of a software guy, but if you could get the script to actually patch the ROM image automatically, that would be ever better!

feipoa wrote on 2024-07-18, 07:07:

Indeed, this seems cleaner. Thanks!

I also think an option to have the script modify the BIOS would be a nice to have. e.g. "do you want this programme to amend your BIOS with this information: Y or N?"

Finally your wish is fulfilled 😁 I got back here due to some AMI 286 BIOS tinkering.

Here's the new Python code for the AMI "color" BIOS checksum calculator script with auto-patching option for 64 kB BIOS-dump file - just as you suggested. It also have some basic checks if given BIOS-dump file exists and if it is exactly 64 kB in size. And don't worry, the script does not messes with the original BIOS-dump file, but creates a copy with corrected checksum bytes (with ".NEW" file extension):

1#!/usr/bin/env python3
2# amichksumcalc v.2
3# loads ami color bios dump-file, calculates checksum (16-bit sequential) and values needed to validate (if checksum != 0), and patches file if chosen to
4
5import sys
6import os.path
7import shutil
8
9if len(sys.argv) != 2:
10    print(f'Usage: {sys.argv[0]} <64 kB BIOS ROM-dump file>')
11    sys.exit()
12
13bios_file_name = sys.argv[1]
14
15if not os.path.isfile(bios_file_name):
16    print(f'Error: "{bios_file_name}" file does not exist!')
17    sys.exit()
18
19if os.path.getsize(bios_file_name) !=65536:
20    print(f'Error: "{bios_file_name}" file is not 64 kB in size!')
21    sys.exit()
22
23try:
24    with open(bios_file_name, mode='rb') as file:
25        bios_data = file.read()
26        file.seek(65360, 0)
27        first_checksum_byte = file.read(1)
28        second_checksum_byte = file.read(1)
29        print(f'Checksum bytes read from "{bios_file_name}" file at address 0xFF50 (hex, LE): "{first_checksum_byte.hex().upper()} {second_checksum_byte.hex().upper()}".')
30except:
31    print(f'Error while reading "{bios_file_name}" file!')
32    sys.exit()
33
34block_count = int(len(bios_data) / 16)
35checksum = 0
36
37for block in range(0, block_count):
38    bios_block = bios_data[block * 16: block * 16 + 16]
39    block_checksum = 0
40
41    for byte_pair in range(0, 8):
42        byte_pair_hex = (bios_block[byte_pair * 2 + 1: byte_pair * 2 + 2].hex() + bios_block[byte_pair * 2:byte_pair * 2 + 1].hex())
43        byte_pair_dec = int(byte_pair_hex, 16)
44        block_checksum += byte_pair_dec
45
46    block_checksum %= 65536
47    checksum += block_checksum
48
49checksum %= 65536
50
51if checksum == 0:
52    print(f'Checksum for "{bios_file_name}" file equals zero.')
53    print('No actions needed.')
54else:
55    print(f'Checksum for "{bios_file_name}" file does not equal zero!')
56    print(f'Current checksum (dec): {str(checksum)}; (hex, LE): "{int(checksum).to_bytes(2, "little").hex(" ").upper()}".')
57
58    two_byte_addition_strhex = int(65536 - checksum).to_bytes(2, "little").hex(" ").upper()
59    print(f'2 bytes addition to current checsum needed to validate it (hex, LE): "{two_byte_addition_strhex}".')
60

61    new_first_byte_sum_dec = int(bytearray.fromhex(two_byte_addition_strhex)[0] + int.from_bytes(first_checksum_byte, "little"))
62    correction_sum_strhex = new_first_byte_sum_dec.to_bytes(2, "little").hex(" ").upper()
63    new_second_byte_sum_dec = int(bytearray.fromhex(two_byte_addition_strhex)[1] + int(bytearray.fromhex(correction_sum_strhex)[1]) + int.from_bytes(second_checksum_byte, "little"))
64
65    new_first_byte_strhex = new_first_byte_sum_dec.to_bytes(2, "little").hex(" ").upper().split(" ")[0]
66    new_second_byte_strhex = new_second_byte_sum_dec.to_bytes(2, "little").hex(" ").upper().split(" ")[0]
67
68    choices = ('', 'n','y')
69
70    while True:
71        ch = input(f'Do you want to auto-patch the checksum bytes in "{bios_file_name}" file? Enter [y/N]: ')
72        if ch.lower() not in choices:
73            print(f'Error: Invalid choice "{ch}". Try again!')
74            continue
75        else:
76            break
77
78    if not ch or ch.lower() == 'n':
79        print('No actions taken.')
80        print(f'Manually hex-edit checksum bytes in "{bios_file_name}" file at address 0xFF50 with these values (hex, LE): "{new_first_byte_strhex} {new_second_byte_strhex}".')
81    else:
82        new_bios_file_name = bios_file_name.split('.')[0] + '.NEW'
83        shutil.copy(bios_file_name, new_bios_file_name)
84        print(f'Original "{bios_file_name}" file was copied to "{new_bios_file_name}".')
85
86        try:
87            with open(new_bios_file_name, mode='rb+') as file:
88                file.seek(65360, 0)
89                file.write(bytearray.fromhex(new_first_byte_strhex))
90                file.write(bytearray.fromhex(new_second_byte_strhex))
91                print(f'Checksum bytes replaced in "{new_bios_file_name}" file at address 0xFF50 with these values (hex, LE): "{new_first_byte_strhex} {new_second_byte_strhex}".')
92        except:
93            print(f'Error while writing "{new_bios_file_name}" file!')
94            sys.exit()
95        print(f'Original unmodified "{bios_file_name}" file is still intact.')
96        print(f'Now you can use freshly created "{new_bios_file_name}" file with corrected checksum bytes.')

The newest final version (added BIOS checksum check skip simple hack revert and other extras) of this script is HERE.

I think I tested everything in this script without problems.

Nice.

For dozens of 286 through 386 boards, I have already modified my BIOSes with jake's process to skip the checksum. Does your script check for this condition and not skip the checksum? Or are users of this script needing to manually revert their checksum skip procedure?

feipoa wrote on 2025-06-21, 01:39:

Nice.

For dozens of 286 through 386 boards, I have already modified my BIOSes with jake's process to skip the checksum. Does your script check for this condition and not skip the checksum? Or are users of this script needing to manually revert their checksum skip procedure?

Nope, the script does not check for any BIOS executable code patching. It checks only if the given (path + ) filename exists as file and if there is such file it checks it's size. Then if the size of given file is exactly 64 kB the it proceeds - reads the two checksum bytes starting at address 0xFF50, calculates the checksum for the file and checks if it's equal to 0 - if not: asks to auto-correct the two checksum bytes (at same address 0xFF50) in a copy of the original given file (with file extension ".NEW").

P.S. I found the info needed for this patch in the first post of the thread. So, the byte "FA" that is patched to "EB" can be found by searching for "00 80 33 F6 2E AD 03 D8 E2 FA 74 06 BD 09 00" pattern. I need someone with more machine code reading skills to confirm if this pattern is suitable for searching (i.e. is it constant?) in all AMI "color" BIOSes, so I can try to implement the anti-bypassing-checksum-check-autopatch in the checksum correction script.

Double plus good. Thanks!

analog_programmer wrote on 2025-06-21, 04:40:

P.S. I found the info needed for this patch in the first post of the thread. So, the byte "FA" that is patched to "EB" can be found by searching for "00 80 33 F6 2E AD 03 D8 E2 FA 74 06 BD 09 00" pattern. I need someone with more machine code reading skills to confirm if this pattern is suitable for searching (i.e. is it constant?) in all AMI "color" BIOSes, so I can try to implement the anti-bypassing-checksum-check-autopatch in the checksum correction script.

The byte string 2E AD 03 D8 E2 FA 74 06 does not have any absolute addresses in it, and captures the "essence" of the 16-bit checksum calculation. I suggest you use that in your script to verify that what's being passed in is actually an AMIBIOS that uses this calculation, before doing the checksum change at ff50. And changing 74 to EB is the easiest, but not the only way to patch out the check, but since it's the one most openly discussed here, perhaps it's worth supporting.

jakethompson1 wrote on 2025-06-21, 18:24:

The byte string 2E AD 03 D8 E2 FA 74 06 does not have any absolute addresses in it, and captures the "essence" of the 16-bit checksum calculation. I suggest you use that in your script to verify that what's being passed in is actually an AMIBIOS that uses this calculation, before doing the checksum change at ff50. And changing 74 to EB is the easiest, but not the only way to patch out the check, but since it's the one most openly discussed here, perhaps it's worth supporting.

Thanks for your response, jakethompson1.

Then I'll use "2E AD 03 D8 E2 FA EB 06" bytes pattern to check if the dump-file was patched with the simplest possible checksum checking bypass hack which is described in this thread, and if found - the "EB" byte will be reverted back to "74". Probably there is a possibility for patching the BIOS function checksum calculating to return always 0, but the primary goal of the checksum calculator was not to remove the BIOS executable code patches. This "simple checksum bypass patch" check and depatching when restoring a valid checksum will be a bonus 😉

I didn't bother to think for some complex checking if the processed file is a real AMI "color" BIOS, 'cause I don't believe that someone sane will use it on 64 kB Award dump-file expecting to achieve something usable out of it. And in the end the original processed file remains unchanged. But if you have some clue on what to check for - for example some exact string or some other constant thing that is unique and can be found only in all of this AMI "color" BIOSes, I'm open for suggestions to improve the script reliability.

That's my suggestion, to require that the input file have 2E AD 03 D8 E2 FA 74 06 in it somewhere, and if so, you presume there is a 16-bit checksum stored at FF50. This is better than trying to do it based on the copyright message or BIOS date IMO.

jakethompson1 wrote on 2025-06-21, 19:29:

That's my suggestion, to require that the input file have 2E AD 03 D8 E2 FA 74 06 in it somewhere, and if so, you presume there is a 16-bit checksum stored at FF50. This is better than trying to do it based on the copyright message or BIOS date IMO.

So the check for a real AMI "color" BIOS-dump file will be If the file contains one of these two patterns: "2E AD 03 D8 E2 FA 74 06" (for unpatched) or "2E AD 03 D8 E2 FA EB 06" (for patched). And of course the 64 kb length check. As simple as that. And if the second pattern is found, then the file will be first de-patched (before any checksum calculations).

Tomorrow will be a good day for new script version 😉

Thanks for adding code to revert the previous'skip checksum' mod. Looks like I will have a lengthy upgrade project for my 286-386 systems. They all have been retro-fitted with PS/2 headers.

feipoa wrote on 2025-06-22, 07:27:

Thanks for adding code to revert the previous'skip checksum' mod. Looks like I will have a lengthy upgrade project for my 286-386 systems. They all have been retro-fitted with PS/2 headers.

Anonymous Coward wrote on 2025-06-21, 12:19:

Double plus good. Thanks!

As I promised yesterday the final Python script for the amichksumcalc v.3. is ready.

The code is rewritten so it can be more readable and reusable. The script now checks if given file is real AMI "color" BIOS and also reverts the well known simple hack for BIOS checksum check bypass if found - as suggested by jakethompson1 . The script works with a copy of the original given file - a temporary .TMP file and if all the auto-patching process is completed successfully renames the temp file to one with .PCH extension (for the final fully patched file), otherwise the temporary file remains, if process is interrupted by some reason. The original given BIOS-dump file is never altered.

Just read the messages carefully when using the script!

It took me a couple of hours to test and adjust everything, and here is the new code:

1#!/usr/bin/env python3
2# amichksumcalc v.3 by analog_programmer, based on ahyeadude's AMI "color" BIOS checksum algorithm
3# Thanks to ahyeadude, jakethompson1, feipoa and Anonymous Coward from vogons.org
4
5import sys
6import os
7import shutil
8
9def checksum_calc(bytes_data):
10    block_count = len(bytes_data) // 16
11    checksum = 0
12    for block in range(0, block_count):
13        bios_block = bytes_data[block * 16:block * 16 + 16]
14        block_checksum = 0
15        for byte_pair in range(0, 8):
16            byte_pair_hex = bios_block[byte_pair * 2 + 1:byte_pair * 2 + 2].hex() + bios_block[byte_pair * 2:byte_pair * 2 + 1].hex()
17            byte_pair_dec = int(byte_pair_hex, 16)
18            block_checksum += byte_pair_dec
19        block_checksum %= 65536
20        checksum += block_checksum
21    checksum %= 65536
22    return  checksum
23
24def confirm_choice(question):
25    choices = ('', 'n','y')
26    while True:
27        choice = input(f'{question} Enter [y/N]: ')
28        if choice.lower() not in choices:
29            print(f'Error: Invalid choice "{choice}". Try again!')
30            continue
31        else:
32            break
33    if not choice or choice.lower() == 'n':
34        return False
35    return True
36
37def hex_str2byte(hex_str):
38    return bytearray.fromhex(hex_str)
39
40def hex_str2int(hex_str):
41    return int.from_bytes(bytearray.fromhex(hex_str), "little")
42
43def int2hex_str(int_num, idx=None):
44    if idx or idx == 0:
45        return int_num.to_bytes(2, "little").hex(" ").upper().split(" ")[idx]
46    return int_num.to_bytes(2, "little").hex(" ").upper()
47
48def byte2int(bytes_data):
49    return int.from_bytes(bytes_data, "little")
50
51def byte2hex_str(bytes_data):
52    return bytes_data.hex().upper()
53
54def print_no_further_actions():
55    print('No further actions will be taken.')
56
57def file_op_error(file_name, action):
58    print(f'Error while {action} "{file_name}" file!')
59    sys.exit()
60

61def check_file_exists(file_name):
62    if os.path.isfile(file_name):
63        return True
64    return False
65
66def file_delete(file_name):
67    if check_file_exists(file_name):
68        try:
69            print(f'Deleting "{file_name}"...')
70            os.remove(file_name)
71            print(f'"{file_name}" file was deleted.')
72        except:
73            file_op_error(file_name, 'deleting')
74
75def file_copy(file_name1, file_name2):
76    if check_file_exists(file_name2):
77        print(f'Warning: "{file_name2}" file already exists!')
78        if not confirm_choice(f'Do you want to overwrite "{file_name2}" file with "{file_name1}"?'):
79            print_no_further_actions()
80            sys.exit()
81    try:
82        print(f'Copying "{file_name1}" file to "{file_name2}" file...')
83        shutil.copy(file_name1, file_name2)
84        print(f'"{file_name1}" file was copied to "{file_name2}" file.')
85        return file_name2
86    except:
87        file_op_error(file_name2, 'creating')
88
89def file_rename(file_name1, file_name2):
90    if check_file_exists(file_name2):
91        file_copy(file_name1, file_name2)
92        if check_file_exists(file_name1):
93            file_delete(file_name1)
94        return file_name2
95    else:
96        try:
97            print(f'Renaming "{file_name1}" file to "{file_name2}"...')
98            os.rename(file_name1, file_name2)
99            print(f'Original "{file_name1}" file was renamed to "{file_name2}".')
100            return file_name2
101        except:
102            file_op_error(file_name1, 'renaming')
103
104def write_file_single_byte(file_name, byte_position, byte_data):
105    try:
106        with open(file_name, mode='rb+') as file:
107            file.seek(byte_position, 0)
108            file.write(byte_data)
109    except:
110        file_op_error(file_name, 'writing')
111
112def read_file_single_byte(file_name, byte_position):
113    try:
114        with open(file_name, mode='rb') as file:
115            file.seek(byte_position, 0)
116            return file.read(1)
117    except:
118        file_op_error(file_name, 'reading')
119
120def read_file_binary_contents(file_name):
121    try:
122        with open(file_name, mode='rb') as file:
123            return file.read()
124    except:
125        file_op_error(file_name, 'reading')
126
127def check_ami(file_name):
128    global hacked
129    file_bytes_data = read_file_binary_contents(file_name)
130    idx = 0
131    # search for unpatched string "2E AD 03 D8 E2 FA 74 06"
132    idx = file_bytes_data.find(b'\x2e\xad\x03\xd8\xe2\xfa\x74\x06', idx)
133    if idx != -1:
134        print(f'"{file_name}" file seems like authentic 64 kB AMI "color" BIOS.')
135        return True
136    idx = 0
137    # search for patched string "2E AD 03 D8 E2 FA EB 06"
138    idx = file_bytes_data.find(b'\x2e\xad\x03\xd8\xe2\xfa\xeb\x06', idx)
139    if idx != -1:
140        hacked = True
141        print(f'"{file_name}" file seems like hacked 64 kB AMI "color" BIOS.')
142        print(f'Restoring "{file_name}" file to authentic 64 kB AMI "color" BIOS...')
143        # restoring unpatched string "2E AD 03 D8 E2 FA 74 06"
144        file_address = idx + 6
145        byte4patch = read_file_single_byte(file_name, file_address)
146        write_file_single_byte(file_name, file_address, b'\x74')
147        print(f'Byte "{byte2hex_str(byte4patch)}" replaced in "{file_name}" file at address 0x{hex(file_address)[2:].upper()} with this value (hex): "74".')
148        print(f'"{file_name}" file restored to authentic 64 kB AMI "color" BIOS.')
149        return True
150    return False
151
152# main code:
153# check CL parameters
154if len(sys.argv) != 2:
155    print(f'Usage: {sys.argv[0]} <64 kB BIOS ROM-dump file>')
156    sys.exit()
157
158# gets BIOS ROM-dump file name
159bios_file_name = sys.argv[1]
160
161# check if BIOS ROM-dump file exists
162if not check_file_exists(bios_file_name):
163    print(f'Error: "{bios_file_name}" file does not exist!')
164    sys.exit()
165
166# check if BIOS ROM-dump file is 64 kB in size
167if os.path.getsize(bios_file_name) !=65536:
168    print(f'Error: "{bios_file_name}" file is not 64 kB in size!')
169    sys.exit()
170print(f'"{bios_file_name}" file is 64 kB in size!')
171
172# copy BIOS ROM-dump file to BIOS ROM-dump file with ".TMP" extension
173new_bios_file_name = bios_file_name.split('.')[0] + '.TMP'
174print(f'Original "{bios_file_name}" will be copied to "{new_bios_file_name}" file.')
175file_copy(bios_file_name, new_bios_file_name)
176
177# check if BIOS ROM-dump file is genuine AMI "color" BIOS or hacked AMI "color" BIOS
178hacked = False
179if not check_ami(new_bios_file_name):
180    print(f'Error: "{new_bios_file_name}" file is not AMI "color" BIOS ROM-dump!')
181    file_delete(new_bios_file_name)
182    print_no_further_actions()
183    sys.exit()
184
185# print two checksum bytes from BIOS ROM-dump file at address 0xFF50
186first_checksum_byte = read_file_single_byte(new_bios_file_name, 65360)
187second_checksum_byte = read_file_single_byte(new_bios_file_name, 65361)
188print(f'Checksum bytes read from "{new_bios_file_name}" file at address 0xFF50 (hex, LE): "{byte2hex_str(first_checksum_byte)} {byte2hex_str(second_checksum_byte)}".')
189
190# calculating BIOS ROM-dump file checksum
191bios_file_checksum = checksum_calc(read_file_binary_contents(new_bios_file_name))
192
193# validating BIOS ROM-dump file checksum
194if bios_file_checksum != 0:
195    print(f'Checksum for "{new_bios_file_name}" file does not equals zero.')
196    print(f'Current checksum (dec): {bios_file_checksum}; (hex, LE): "{int2hex_str(bios_file_checksum):}".')
197    # calculating addition sum for correction
198    two_byte_addition = 65536 - bios_file_checksum
199    print(f'2 bytes addition to current checksum needed to validate it (dec) {two_byte_addition}; (hex, LE): "{int2hex_str(two_byte_addition)}".')
200    # calculating two new checksum bytes for BIOS ROM-dump file
201    new_first_checksum_byte = hex_str2int(int2hex_str(two_byte_addition, 0)) + byte2int(first_checksum_byte)
202    correction = hex_str2int(int2hex_str(new_first_checksum_byte, 1))
203    new_second_checksum_byte = hex_str2int(int2hex_str(two_byte_addition, 1)) + byte2int(second_checksum_byte) + correction
204    # ask to proceed with auto-patching of BIOS ROM-dump file
205    if confirm_choice(f'Do you want to auto-patch the checksum bytes in "{new_bios_file_name}" file?'):
206        write_file_single_byte(new_bios_file_name, 65360, hex_str2byte(int2hex_str(new_first_checksum_byte, 0)))
207        write_file_single_byte(new_bios_file_name, 65361, hex_str2byte(int2hex_str(new_second_checksum_byte, 0)))
208        patched_bios_file_name = file_rename(new_bios_file_name, bios_file_name.split('.')[0] + '.PCH')
209        print(f'Checksum bytes replaced in "{patched_bios_file_name}" file at address 0xFF50 with these values (hex, LE): "{int2hex_str(new_first_checksum_byte, 0)} {int2hex_str(new_second_checksum_byte, 0)}".')
210        print(f'Original unmodified "{bios_file_name}" file is still intact.')
211        print(f'Now you can use freshly created "{patched_bios_file_name}" file with corrected checksum bytes{" and removed checksum hack" if hacked else ""}.')
212    else:
213        print_no_further_actions()
214        print(f'Manually hex-edit checksum bytes in "{new_bios_file_name}" file{" with removed checksum hack" if hacked else ""} at address 0xFF50 with these values (hex, LE): "{int2hex_str(new_first_checksum_byte, 0)} {int2hex_str(new_second_checksum_byte, 0)}".')
215else:
216    print(f'Checksum for "{new_bios_file_name}" file equals zero.')
217    file_delete(new_bios_file_name)
218    print('No actions needed.')
219    print(f'Original unmodified "{bios_file_name}" file is still intact.')

I'm waiting for your feedback...

UPDATE: Attached "amichksumcalc3.py" script in zip-archive:

There will be no further updates to the script as there's zero feedback as it seems useless and of no interest to anyone. I've already lost enough time in writing and testing it, so this is the final version and if in the future someone decides to use it - it's still here.

If you're waiting for me, I won't have time to do any computer work until the Fall. I'm in summer home repair mode and have lots going on.

feipoa wrote on 2025-06-24, 06:30:

If you're waiting for me, I won't have time to do any computer work until the Fall. I'm in summer home repair mode and have lots going on.

I'm waiting for someone to test the script and give some feedback, 'cause there's always a possibility that I've missed or messed something.