Changeset 605 in xtideuniversalbios for trunk/Assembly_Library/Inc

Timestamp:

May 8, 2021, 6:55:56 PM (4 years ago)

Author:

Krister Nordvall

Message:

Changes:

• The "Remove other hard drives" option in the Boot settings menu in XTIDECFG is now exposed in all BIOS builds. This is needed because the system BIOS in at least two Zenith computer models (Z-161 and Z-171) does not clear the BDA HD count which causes it to increment on warm boot. Running "Auto Configure" in XTIDECFG now also tries to identify these machines by doing a CRC check on the system BIOS and sets the option to YES if a match is found.
• WORD_ALIGN is now 2 for XT builds. This should benefit XT class machines with 8086 and NEC V30 CPU:s and the cost is negligible (1 byte for the XT BIOS builds and 12 bytes for XTIDECFG.COM).
• Other minor optimizations.

Location:

trunk/Assembly_Library/Inc

Files:

• CMOS.inc (modified) (1 diff)
• Emulate.inc (modified) (1 diff)

trunk/Assembly_Library/Inc/CMOS.inc

@@ -31 +31 @@
 ; Almost all of the CMOS locations are vendor specific and
 ; there is very little standardation
-HARD_DISK_TYPES                 EQU     12h     ; Windows 95 reads this to check if IDE drives
+HARD_DISK_TYPES                 EQU     12h     ; Windows 9x reads this to check if IDE drives
                                                 ; are present so it should be safe to access this.
                                                 ; Bits 0...3 Hard Disk 1 type (Primary Slave)

trunk/Assembly_Library/Inc/Emulate.inc

@@ -60 +60 @@
     %endif
 %else ; XT
-    JUMP_ALIGN      EQU     1
-    WORD_ALIGN      EQU     1
+    JUMP_ALIGN      EQU     1   ; 2 is optimal for 8086 and NEC V30 CPUs but it's not worth the ROM space for most XT machines with 8088 or NEC V20 CPUs.
+    WORD_ALIGN      EQU     2   ; The same applies here but the cost of ROM space is negligible.
 %endif