Add basic support for TI-99 disks.

README.md

@@ -137,6 +137,7 @@ choices because they can store multiple types of file system.
 | [`rx50`](doc/disk-rx50.md) | Digital RX50: 400kB 5.25" 80-track 10-sector SSDD | 🦖 | 🦖 |  |
 | [`smaky6`](doc/disk-smaky6.md) | Smaky 6: 308kB 5.25" 77-track 16-sector SSDD, hard sectored | 🦖 |  | SMAKY6  |
 | [`tartu`](doc/disk-tartu.md) | Tartu: The Palivere and variations | 🦄 | 🦖 | CPMFS  |
+| [`ti99`](doc/disk-ti99.md) | TI-99: 90kB 35-track SSSD | 🦖 |  |  |
 | [`tids990`](doc/disk-tids990.md) | Texas Instruments DS990: 1126kB 8" DSSD | 🦖 | 🦖 |  |
 | [`tiki`](doc/disk-tiki.md) | Tiki 100: CP/M |  |  | CPMFS  |
 | [`victor9k`](doc/disk-victor9k.md) | Victor 9000 / Sirius One: 1224kB 5.25" DSDD GCR | 🦖 | 🦖 |  |

src/formats/build.py

@@ -36,6 +36,7 @@ formats = [
     "shugart_drive",
     "smaky6",
     "tartu",
+    "ti99",
     "tids990",
     "tiki",
     "victor9k",

src/formats/ti99.textpb

@@ -0,0 +1,44 @@
+shortname: 'TI-99'
+comment: '90kB 35-track SSSD'
+read_support_status: DINOSAUR
+
+documentation:
+<<<
+The TI-99 was a deeply weird microcomputer from 1981, whose main claim to fame
+was being built around a 16-bit TMS9900 CPU --- and also having only 256 bytes
+of system RAM, with an additional 16kB of video RAM, requiring the BASIC to
+store the user's program in video RAM.
+
+It had an optional rack-mount expansion system with an optional disk drive. This
+was controlled by a standard FD1771 or FD179x chip, meaning a relatively normal
+IBM-scheme disk format of 35 tracks containing nine 256-byte sectors.
+
+FluxEngine can read these.
+>>>
+
+image_reader {
+	filename: "ti99.img"
+	type: IMAGETYPE_IMG
+}
+
+image_writer {
+	filename: "ti99.img"
+	type: IMAGETYPE_IMG
+}
+
+layout {
+	format_type: FORMATTYPE_40TRACK
+	tracks: 40
+	sides: 1
+	layoutdata {
+		sector_size: 256
+		physical {
+			start_sector: 0
+			count: 9
+		}
+	}
+}
+
+decoder {
+	ibm {}
+}