Texas Instruments Personal Learning Tool PLT FHH1

The Datamath Calculator Museum received this unique graphing calculator as a loan from Texas Instruments in February 2008 to photograph and document it.  

We learned from Texas Instruments that they developed a family of next-generation Personal Learning Tool products based on the LINUX operating system. The Dallas, TX based team nicknamed it PET Project and this PLT FHH1 is actually a first generation PET device nicknamed Fido Hand Held. A smaller, portrait oriented PET device was labeled PLT SHH1 for Spot Hand Held. The second generation PET device PLT SU1 was known as Toto Hand Held.

We assume that only about 500 prototypes of the PLT FHH1 were used for field tests but none showed up on eBay till now.  

The backside of the calculator teases us with some valuable information as a start point of further research: Model No: PLT - FHH1, © 2002, Made in Taiwan.

Comparing the PLT FHH1 with the PLT SHH1 reveals an important difference: While the smaller SHH1 still features a traditional keyboard for easy operation, hosts the larger FHH1 just 8 keys and the cursor control. Similar to a modern PDA (Personal Digital Assistant) is the calculator operated by a Stylus. We assume that a keyboard was developed as an optional, external input device.

The Li-ion battery of the PLT FHH1 states three different products to be powered with:

• PLT SHH1: Spot Hand Held
• PLT FHH1: Fido Hand Held
• PLT WS1:  Wireless Sled - A cradle with wireless LAN support

Architecture: Dismantling the PLT FHH1 reveals a modern architecture based on the OMAP architecture introduced by Texas Instruments already in 2001. Learn more about the Hardware Architecture of TI’s Graphing Calculators. The different memory chips used in this Engineering Samples promised an unbelievable huge workspace of 32M Bytes and even an additional slot for a SD Memory Card. In addition we recognized an unknown Philips CA4885 device.  

Processor: The first generation OMAP™ 1510 combines in one system the TMS320C55x DSP (Digital Signal Processor) with a ARM925 RISC (Reduced Instruction Set Computing) to perform the perfect balance between performance and power consumption for mobile products. It was used between 2002 and 2006 in products like the Palm Tungsten T, Hewlett Packard iPAQ H6340, and Nokia 9300/9500 Communicator.  

Memory: The PLT FHH1 makes use of three different memory chips:

Flash memory is non-volatile and does not need a battery to maintain the information stored in the chip. In the past years two different technologies emerged in parallel with some advantages and disadvantages. 

The NOR Flash-ROM was invented by Toshiba in 1984 and found its way immediately as a replacement of the more expensive ROM (NRE mask costs) and EEPROM (device costs) memory. The NOR Flash-ROMs use an address and data bus to allow the random access to any memory location. Main disadvantages of the NOR Flash-ROM compared to the NAND Flash-ROM are the higher costs, larger housings and slower write speeds.

The disassembled PLT FHH1 (Manufactured 2002) makes use of one 29LV400TC, manufactured by Fujitsu, Japan with a 256k*16 bits organization. Please keep in mind that even the TI-89 Titanium used 2M*16 bits Flash-ROM.

The NAND Flash-ROM architecture was introduced by Toshiba in 1989 and is based on pages of typically 512 to 2048 Bytes and blocks of typical 32 or 64 pages.

While programming is performed on a page basis, erasure can only be performed on a block basis. NAND Flash-ROMs requires bad block management to be performed by device driver software or hardware. Due to the missing address bus the NAND Flash-ROM chip doesn't allow random access to the individual memory positions and therefore it can't be used for program memory of a microprocessor. Typical use of the NAND Flash-ROM memory is file based mass-memory storage such as memory cards.

The disassembled PLT FHH1 makes use of one Toshiba TC58128A NAND EEPROM with 16M Bytes size compared with 32M Bytes CMOS NAND Flash-ROM located in the later TI-Nspire.

SDRAM is the abbreviation of synchronous dynamic random access memory and is used as program and data memory for microprocessor systems. Each bit of data in a SDRAM is stored in separate capacitor on the integrated circuit. Since these capacitors leak charge over time, the information eventually fades unless the capacitor charge is refreshed periodically.

Because of this refresh requirement, it is a dynamic memory as opposed to SRAM and other static memory. Its advantage over SRAM is its structural simplicity: only one transistor and a capacitor are required per bit, compared to six transistors in SRAM. This allows SDRAM to reach very high density at low cost. Since SDRAM loses its data when the power supply is removed, it is accompanied usually by a NOR Flash memory.

During power-up of the system the program content of the NOR Flash-ROM is simply copied into the SDRAM and executed from there. We assume that the PLT FHH1 uses the SDRAM as workspace for user data but stores changes on them into the NAND Flash-ROM.

The disassembled PLT FHH1 makes use of one Hynix HY57V281620A SDRAM with 8M*16 bits capacity compared with 16M*16 bits SDRAM located in the later TI-Nspire.

Display: The PLT FHH1 uses a high-contrast display with a resolution of 480 * 320 pixels, a huge improvement over the TI-89 Titanium with 100 * 160 pixels or the Voyage 200 with 128 * 240 pixels. The large touch-screen display includes a novel split screen capability with up to 4 views.  

Five components not easily detected on the printed circuit board (PCB) of the display module are the driver circuits of the LC-Display. They are just bare chips mounted on a flexible piece of circuit board attached between the display and the main PCB. The chips are manufactured by Sharp, Japan and drive 160 rows resp. columns, each.  

Connectivity: The PLT FHH1 features a huge variety of connectors to the outside world:

The serial port of the calculator allows the connection to the Calculator-Based Laboratory system CBL 2 and the Calculator-Based Ranger CBR and probably an external keyboard.

ROM-Versions:

• PLT FHH1

no information available

Texas Instruments worked secretly on the Phoenix 1 and announced in 2006 the TI-Nspire CAS+, but it took another year before the long-awaited TI-Nspire calculator family arrived finally July 2007 in the store shelves.

If you have additions to the above article please email: joerg@datamath.org.

© Joerg Woerner, March 6, 2008. No reprints without written permission.