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F800 ROM error on 5150 16KB-64KB board
- Thread starter dreddnott
- Start date
modem7
10k Member
Luke's info is probably based on the BIOS info I put in Mike's '5150 vs. 5160 FAQ' thread.
When I added the "(U29 BIOS = 8K, U30-U33 BASIC = 8K each)" text in the 5150 BIOS listings post, the bit about U29 being the BIOS chip was based on an Internet site I located.
Now that I have a 5150 of my own (with Technical Reference on the way), I just proven to myself that U29 is not the BIOS - the BIOS is U33.
U29 = F600-F7FF = BASIC
U30 = F800-F9FF = BASIC
U31 = FA00-FBFF = BASIC
U32 = FC00-FDFF = BASIC
U33 = FE00-FFFF = BIOS/POST
And so Luke's, "This is first BASIC chip (there are three more in U31, U32 and U33)." should now be "This is second BASIC chip (there are three more in U29, U31 and U32)."
I've modified my post in Mike's '5150 vs. 5160 FAQ' thread, and I'll attempt to contact the author of the Internet site I mentioned.
modem7
10k Member
Dreddnott,
If you had a 5160 or a 5170, then I could have provided a replacement BIOS chip. Not the exact IBM part, but a clone.
Replacing a BIOS chip in a 5150 is a different story.
For those who will comprehend:
If a BIOS chip in a 5160 (U18/U19) or 5170 (U27/U47) fails, I can easily supply a replacement. I simply burn a commonly obtained 27256 EPROM. I have copies of those BIOS chips (as files) and I have spare 27256's. Obviously the replacement needs to be done as a matching set, and some BIOS' are motherboard specific (eg. 16/64K versus 64/256K).
Unfortunately, in the 5150, the BIOS chips are not so easy to replace. IBM used a PROM chip that nowadays is expensive to purchase. The AM9264DPC (or equivalent) only seems to be stocked by specialist IC supply companies that deal with orders worth $500 or more. Even if I obtained some, finding (or making) something to burn them is the second hurdle. Doable but a lot of expense/effort, particularly when you consider that periodically, 5150 motherboards can be obtained on eBay for around the $10 mark (plus shipping).
I can't find a pin-for-pin EPROM equivalent for the AM9264DPC.
A 'messy' EPROM based solution is on the Internet at: http://groups.google.com/group/comp.../a2a940c74751409e?hl=la&lr=&ie=UTF-8&oe=UTF-8
In that solution, a modified 2764 EPROM (after being burned) is used. The result will look bad. Not only will the chip have wires running over/around it, but a 28 pin chip is being fitted into a 24 pin socket (i.e. overhang on both ends).
Creating a binary file from a 5150 BIOS chip
--------------------------------------------
In this example, a binary file named F600_U29.BIN is created that contains the contents of U29 (8K block at F600:0)
C:\>DEBUG
-NF600_U29.BIN
-RCX
CX 0000
:2000
-MF600:0 2000 0100
-W0100
Writing 2000 bytes
-Q
If you had a 5160 or a 5170, then I could have provided a replacement BIOS chip. Not the exact IBM part, but a clone.
Replacing a BIOS chip in a 5150 is a different story.
For those who will comprehend:
If a BIOS chip in a 5160 (U18/U19) or 5170 (U27/U47) fails, I can easily supply a replacement. I simply burn a commonly obtained 27256 EPROM. I have copies of those BIOS chips (as files) and I have spare 27256's. Obviously the replacement needs to be done as a matching set, and some BIOS' are motherboard specific (eg. 16/64K versus 64/256K).
Unfortunately, in the 5150, the BIOS chips are not so easy to replace. IBM used a PROM chip that nowadays is expensive to purchase. The AM9264DPC (or equivalent) only seems to be stocked by specialist IC supply companies that deal with orders worth $500 or more. Even if I obtained some, finding (or making) something to burn them is the second hurdle. Doable but a lot of expense/effort, particularly when you consider that periodically, 5150 motherboards can be obtained on eBay for around the $10 mark (plus shipping).
I can't find a pin-for-pin EPROM equivalent for the AM9264DPC.
A 'messy' EPROM based solution is on the Internet at: http://groups.google.com/group/comp.../a2a940c74751409e?hl=la&lr=&ie=UTF-8&oe=UTF-8
In that solution, a modified 2764 EPROM (after being burned) is used. The result will look bad. Not only will the chip have wires running over/around it, but a 28 pin chip is being fitted into a 24 pin socket (i.e. overhang on both ends).
Creating a binary file from a 5150 BIOS chip
--------------------------------------------
In this example, a binary file named F600_U29.BIN is created that contains the contents of U29 (8K block at F600:0)
C:\>DEBUG
-NF600_U29.BIN
-RCX
CX 0000
:2000
-MF600:0 2000 0100
-W0100
Writing 2000 bytes
-Q