A few days ago, someone from MAME wanted me to dump some old ROMs. I decided to do a picture story of the process!
In the above photo, you can see:
* Tandon full height 5.25" floppy drive
* Xebec hard disk controller
* IBM floppy disk controller
The system below the controller cards is an IBM 5160- aka the PC XT. 8088 CPU at 4.77 MHz with 8 expansion slots and 640kB RAM.
The machine I use to dump/burn (EP)ROMs at present is an IBM 5170, aka PC AT. This is a 1984 Model 1 variant. 6 MHz Intel 80286 CPU with Intel 80287 FPU. 640kB conventional memory, 640kb EXPANDED memory, and 768kb extended memory.
The EPROM burner/programmer I use is a Needham's PB-10. It was a gift from a professor at Uni, who knew I could give it a good home :3; I have plenty of systems with ISA slots, after all!
First ROM to dump is original to the Xebec card. These ROMs are so old, they predate the JEDEC pinout of the 27xx-series EPROMs. The equivalent EPROM of this type goes under the name of "23xx-series" or "Motorola 68764".
This is the primary GUI of the ROM dumping program. Notice base addr, ROM type, range, etc.
Aaaaand success for the first ROM! It's an 8086 binary that implements the hard drive portion of Int 0x13 :D.
And now, the second of the two ROMs. This is not original; looks like a previous owner replaced it with an equivalent EPROM. Maybe the original ROM went bad?
This binary is z80 code; my Xebec controller is the third revision IBM made:
The first revision doesn't have a z80 and only supports a 10MB hard drive; other revisions support up to 4 types of hard drive. The z80 binary also has many empty patches. This leads me to believe the z80 is only there to set the controller IC registers at boot.
So now, I have both ROMs dumped, and need to xfer them to the Internet. How should I go about this? Let's make it fun!
I'm going to run an FTP server on my 6 MHz 286 and retrieve the ROMs to upload to my website! :D
I connect my AT to the Internet using Thinnet aka 10BASE2 Ethernet; 10Mbps Ethernet over RG-58 coaxial cable. No modern router understands Thinnet so you need either an old router/hub or a converter box :).
Yes, the converter is sitting on a DDS4 tape drive :P...
And hey, look at that! The FTPSRV works! :) I love mTCP (TCP stack for DOS)!
Pictures of all 3 variants of Xebec controller can be found here: http://www.minuszerodegrees.net/ibm_xebec/ibm_xebec.htm
Oh damn. It looks like the original revision of this card _does_ in fact have a z80 and I missed it b/c it's not marked well.
I still stand by my prediction for what the z80 is actually used for until I can take a look though!
Credit to TubeTimeUS on Twitter for pointing this out! :D
@cr1901 i cannot remember the last time i saw a 286. does Indiana Jones ever show up and yell at you "it belongs in a MUSEUM!"
@cr1901 this thread rules, thanks for sharing!
@cr1901 at this point wouldn't it be easier just to reverse engineering and reprogramming the whole Game?
@bithive Not a game, it's hard disk controller firmware for the IBM 5160; it probably already matches an existing set, tbh.
But a MAME dev wanted me to dump it just in case.
"A few days ago, someone from MAME wanted me to dump some old ROMs. I decided to do a picture story of the process!"
*Dumps ROM chips in the trash*
Sorry, couldn't resist 😅
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