romdisk: specification

diff --git a/romdisk.txt b/romdisk.txt
new file mode 100644 (file)
index 0000000..008099b
--- /dev/null
+++ b/romdisk.txt
@@ -0,0 +1,36 @@
+CP/M ROMDISK
+============
+
+- implemented on port 0x0F:
+--- write track number (0..191)
+--- read 128 times
+--- not writeable
+--- 44 tracks reserved for CPM.SYS
+
+- create/populate image with
+--- mkfs.cpm -f romdisk -b cpm.sys <image>
+--- cpmcp -f romdisk <image> <hostfile> <user>:
+
+DPB:
+> SPT = 1
+> BSH = 3
+> BLM = 7
+> EXM = 0
+> DSM = 23
+> DRM = 32
+> AL0 = 128
+> AL1 = 0
+> CKS = 0
+> OFF = 44
+
+/etc/cpmtools/diskdefs:
+> diskdef romdisk
+>   seclen 128
+>   tracks 192
+>   sectrk 1
+>   blocksize 1024
+>   maxdir 32
+>   skew 1
+>   boottrk 44
+> end
+