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