Any luck on this yet? If you're still stuck, let me know and I'll see
what I can do.
-Mark
On Aug 30, 2008, at 9:07 PM, Jonathan Gevaryahu wrote:
I'm looking for a specific rom for an IBM 5150 machine: rom 5700051
at location U33.
This rom was only used on the very earliest (16-64k MB) 5150 machines.
I know Rich Cini has a disassembly of it on his site:
http://highgate.comm.sfu.ca/~rcini/classiccmp/files/PCBios.ASM
but does anyone have the original binary image?
It can easily be dumped from a working 5150 using a dos boot
diskette and the instructions at
http://mess.toseciso.org/dumping:dump_bios_using_debug/
The actual chip is an MK36xxx rom, which requires a pulse train on /
CE in order to read properly. Some eprom programmers will not read
these correctly at all, the first byte will fill the entire rom
image because the address is never re-latched. (MK36xxx roms will
not read properly without a pulse train of HIGH LOW <read data bus
then set next address> HIGH LOW <read data bus then set next
address>, etc. IBM loved to use these, for some reason, and only
switched to real 2364/23256/2764/27256/etc on the ps/2 machines and
the later ATs, and on certain expansion cards such as the Xebec hdd
controller on the XT,which uses a 2764 for the z80 rom.)
The chip can be read in an incompatible eprom programmer by sticking
the chip in some solderless breadboard and wiring it to the rom
socket in the following way:
programmer A0 through an inverter(7404 will work fine) and
connecting to rom /CE
programmer A1 to rom A0
programmer A2 to rom A1
etc.
Data lines connect directly. read the rom as a 27128, then toss the
first(0x00), third(0x02), and every odd(0x0x where x is even) byte
thereafter, and keep the rest.
other than the /CE change, the mk36xxx is pinout compatible to a
2364, which has a different pinout than a 2764 or 27128 does:
+--------------+
A7 |1 +--+ 24| Vcc
A6 |2 23| A8
A5 |3 22| A9
A4 |4 21| A12
A3 |5 20| /CE
A2 |6 2364 19| A10
A1 |7 18| A11
A0 |8 17| D7
D0 |9 16| D6
D1 |10 15| D5
D2 |11 14| D4
Vss |12 13| D3
+--------------+
P.S. does anyone have an IBM 5100 or other machine in the pre-PC
51xx series? I'm looking for info from those, too.
Thanks!
--
Jonathan Gevaryahu
jgevaryahu(@t)hotmail(d0t)com
jzg22(@t)drexel(d0t)edu