ibmapc
Veteran Member
I recently aquired an EPROM programmer from Chuck(G) (Thanks Chuck!), an el-cheapo Chinese UV EPROM eraser and a hand full of 27C256-20 EPROMS. So, I'm thinking I'd like to tweak the BIOS a little on my 5155. My first goal is to modify the POST to eliminate the test routine that causes the floppy drive head carriage to seek back and forth, this can be pretty noisy on a 5155 and causes unnecessary wear and tear on the stepper motor and carriage rails on both floppy drives. Most non-IBM BIOS's just turn on the motor on drive A and check to see if there is a disk to boot. My second goal is to change the routine that initializes the parallel port(s). I have a parallel port that I modified for bi-directional commuinication which works well with one exception. If the port is left in "recieve" mode when a CNTRL-ALT DEL is performed, the port is not initialized durring the reboot and the only remedy is to cycle the power switch. I've searched HI and low for the source code and have only found it in PDF documents that were scanned from the IBM Tech Ref. Obviously, these can not be compiled, and I haven't found a utillity that can reliably convert a PDF to text with zero errors, and I'm not to thrilled to try to Re-type over 2000 lines of code.
So, I'm hoping someone could help me find a text file (preferably with comments) that could be compiled with somthing like Microsoft Macro Assembler 3.01. I would prefer the 05/09/86 version of the IBM XT BIOS but the earlier versions would be OK if that's all that's available.
Thanks in advance
Greg
So, I'm hoping someone could help me find a text file (preferably with comments) that could be compiled with somthing like Microsoft Macro Assembler 3.01. I would prefer the 05/09/86 version of the IBM XT BIOS but the earlier versions would be OK if that's all that's available.
Thanks in advance
Greg
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