Stratum Sprint Hard Drive
The Sprint is an internal hard drive for a PPC laptop. The drive itself is a 3.5" IDE type, occupying the position normally used by the second floppy drive. Its interface occupies the area of the case used by the PPC's modem, and is connected to the PPC's motherboard by means of a soldered ribbon cable.
On a PPC with a modem fitted, the interface would presumably sit behind the modem PCB.
The hard drive interface in situ:
Not covered by the cable, the interface board looks like this:
The drive interface includes a ROM, BIOS, which signs on as 'Broomsleigh Disc BIOS version 1.4.0' and includes the copyright message '(C) Copyright R.T.J.Woollett 1988,1989'. It provides the usual BIOS services on INT 0x13 and INT 0x19, allowing the PPC to access the hard drive and boot from it.
Nonstandard BIOS calls are:
--------B-131E------------------------------- INT 13 - DISK - SET ATA AUTO STANDBY AH = 1Eh AL = standby count (0 to disable, else time in seconds / 5) DL = drive number (bit 7 set for hard disk) Return: CF set on error CF clear if successful --------B-131F------------------------------- INT 13 - DISK - SEND ATA IDENTIFY COMMAND AH = 1Fh DL = drive number (bit 7 set for hard disk) ES:BX -> data buffer Return: CF set on error CF clear if successful Buffer populated (all words swapped into little-endian form)
The BIOS also sets up the hard drive geometry table on INT 0x41. It supports two hard drive geometries — one with 615 cylinders, 4 heads, 17 sectors (~20Mb) and one with 980 cylinders, 5 heads, 17 sectors (~40Mb). It uses INT 0x13/AX=0x1F00 to identify the drive, and selects the 40Mb geometry if the IDENTIFY result reports 1000 or more cylinders.
The BIOS only supports one hard drive (drive 0x80).
The interface appears to use the standard ATA ports at 0x1F0-0x1F7. It also accesses two other ports:
0x1F8: Read at the start of a transfer to/from disk. Possibly to initialize DMA? 0x1FA: Read at the end of a transfer to/from disk. Possibly to finalize DMA?
The following leaflet was provided with the drive:
The drive was also supplied with a specification document:
CAPACITY: 21.4 MB formatted 25.6 MB unformatted NUMBER OF DISKS: 2 NUMBER OF HEADS: 4 NUMBER OF CYLINDERS: 614 NUMBER OF TRACKS: 1230 TRACK DENSITY: 880 TPI RECORDING METHOD: 2.7 RLL DATA TRANSFER RATE: 7.5 MBits/sec AUTOPARK: after 5 sec SEEK TIMES: Track to track 15 msec Average 20 msec Max 120 msec START/STOP TIMES: 5/11 sec (typical) ROTATIONAL SPEED: 2640 rpm POWER REQUIREMENTS: Power-on: 5.0 W (max 7 sec) Read/Write: 3.5 W Wait: 1.4 W MTBF: 22 000 POH MTTR: 0.5 H WEIGHT: 550 grams SHOCK: Non operating: 70 G (@11 msec) Operating: 10 G (@11 msec) VIBRATION: Non operating: 5 G (5-300 Hz) Operating: 0.5 G (5-300 Hz) ENVIRONMENTAL DATE: Ambient Temperature (operating): 0...+50 Degrees C Ambient Temperature (storage): -40...+60 Degrees C Relative Humidity: 8...80 RH (non condensing)
John Elliott 16 October 2015