PC-DOS information updates

_posts/2014-10-17-improved-support-for-pc-at-machines.md

@@ -1,13 +1,13 @@
 ---
 layout: post
-title: Release of PCjs v1.15.5
+title: Improved support for PC AT machines
 date: 2014-10-17 11:00:00
 category: Releases
 permalink: /blog/2014/10/17/
 ---
 
-The [8Mhz IBM PC AT](/devices/pc/machine/5170/ega/1152kb/rev3/debugger/) machine configuration boots in
-v1.15.5 of PCjs now, which includes the following fixes:
+The [8Mhz IBM PC AT](/devices/pc/machine/5170/ega/1152kb/rev3/debugger/) machine configuration now boots in
+[PCjs v1.15.5](https://github.com/jeffpar/pcjs/releases/tag/v1.15.5), which includes the following fixes:
 
 + The BIOS expects memory refresh to occur roughly every 16us, which I've resolved by tying the state
 of the refresh bit in port 0x61 to bit 6 of the CPU cycle count (see *in8042RWReg()* in [chipset.js](/modules/pcjs/lib/chipset.js));

_posts/2014-10-23-improved-pc-dos-700-support.md

@@ -1,21 +1,22 @@
 ---
 layout: post
-title: Release of PCjs v1.15.6
+title: Improved PC-DOS 7.00 Support
 date: 2014-10-23 11:00:00
 category: Releases
 permalink: /blog/2014/10/23/
 ---
 
-This is a fairly minor update that fixes a few Floppy Disk Controller (FDC) issues and one CPU emulation bug
-that prevented PC-DOS 7.00 from working properly.
+[PCjs v1.15.6](https://github.com/jeffpar/pcjs/releases/tag/v1.15.6) is a fairly minor update that fixes a few
+Floppy Disk Controller (FDC) issues and one CPU emulation bug that prevented [PC-DOS 7.00](/disks/pc/dos/ibm/7.00/)
+from working properly.
 
 There are also some Debugger improvements; for example, if you turn on "fdc" and "int" messages in the
 Debugger using the "m fdc on" and "m int on" commands, all FDC (INT 0x13) software interrupts will be logged,
 including descriptions and register values.
 
 PC-DOS 7.00 still can't be setup from its specially-formatted 1.84Mb
-[XDF](http://www.os2museum.com/wp/the-xdf-diskette-format/) distribution disk images, "PC-DOS 7.00 (SETUP Disk 2)"
-through "PC-DOS 7.00 (SETUP Disk 5)", so your best bet is to boot from the 1.44Mb "PC-DOS 7.00 (Boot Disk)".
+[XDF](http://www.os2museum.com/wp/the-xdf-diskette-format/) distribution disk images, "PC-DOS 7.00 (Disk 2)"
+through "PC-DOS 7.00 (Disk 5)", so your best bet is to boot from the 1.44Mb "PC-DOS 7.00 (1.44M Boot)".
 
 Note that you must also use a fairly new 80286 machine configuration, like this
 [8Mhz IBM PC AT](/devices/pc/machine/5170/ega/1152kb/rev3/debugger/),

_posts/2014-10-28-limited-support-for-xdf-disk-images.md

@@ -0,0 +1,23 @@
+---
+layout: post
+title: Limited Support for XDF Diskettes
+date: 2014-10-28 11:00:00
+category: Releases
+permalink: /blog/2014/10/28/
+---
+
+[PCjs v1.15.7](https://github.com/jeffpar/pcjs/releases/tag/v1.15.7) adds support for the
+[XDF Diskette Format](http://www.os2museum.com/wp/the-xdf-diskette-format/), which was used in
+[PC-DOS 7.00](/disks/pc/dos/ibm/7.00/).
+
+However, this support is referred to as "fake" XDF support, because it requires using JSON disk images created
+by DiskDump *without* the experimental "--xdf" option, which is an option that attempts to encode XDF sectors as they
+existed on the original diskettes (ie, with varying lengths and non-standard sector IDs).
+
+"Fake" XDF support works by using conventional 80-track disk images with 23 sectors/track.  No standard PC floppy disk
+format ever used 23 sectors/track, but in this case, by distributing the XDF track data across 23 conventional 512-byte
+sectors, the PC-DOS 7.00 Setup code that reads XDF disks succeeds.  This was probably one of several fall-back options
+built into the PC-DOS XDF code.
+
+*[@jeffpar](http://twitter.com/jeffpar)*  
+*October 28, 2014*