Hello, guys.
I've just soldered my Xi 8088 board (after about a month waiting for spare parts) and it doesn't work 🙁
When I boot my system nothing happens (no beeps, no video signal and so on), POS error system shows 00 code. After several attempts (when I changed everything I can, especially old IC bought from eBay), incidentally I clicked of board's reset switch and POS error became 01. I found BIOS source code and found in it, that it can happen only in one place just after CPU warm boot:
errno.inc:
25 e_boot equ 00h ; Boot the OS
26 e_start equ 01h ; BIOS POST started
27 e_cpu_ok equ 02h ; CPU test passed
bios.asm:
1004 warm_start:
1005 cli ; disable interrupts
1006 cld ; clear direction flag
1007 mov al,e_start
1008 out post_reg,al ; POST start code
1009
1010 ;-------------------------------------------------------------------------
1011 ; test CPU's FLAG register
1012
1013 xor ax,ax ; AX = 0
1014 jb cpu_fail
To approve my guess and changed e_start code to 0x79, recompiled BIOS and reran it. After cold and then warm boot I got "79" on POS error screen!
After that instruction, it turns out that BIOS trying test CPU and after then it will send new POST code e_cpu_fail or will make new checks. But it doesn't happen! It seems that just after first "out" command CPU hangs.
I have no idea what I need to check/replace further.