The AT&T Hobbit chip sets betray their corporate heritage. These are chips designed first and foremost for telecommunications applications. AT&T Microelectronics first offered a set of chips for PDAs (personal digital assistants) in 1992. The 92K Hobbit family, the chips that are used in the Eo Personal Communicator, has five parts: a CPU, a system controller, a bus controller, a video-display controller, and a peripheral-bus controller.
The price seemed high at $99 for the chip set, but it was complete. Late last year, AT&T introduced two new chip sets designed to broaden the line, with trade-offs in performance, system size, cost, battery life, and feature sets.
The ATT92020S processor provides higher performance--it uses a 6-KB prefetch buffer as opposed
to the 3-KB buffer on the 92010--and requires less power than the original 92010 CPU. It also works with all the existing 92010 support chips except for the ISA controller. ISA support doesn't figure very highly in the new Hobbit offerings.
On the other hand, the ATT92020M performs and uses power like the original ATT92010, but it works with a new pair of support chips, a system manager and a video controller, for more integrated performance with a lower chip count. The most highly integrated solution is the ATT92020MX, which needs only a single support chip--a system controller. Both the 92020M and the 92020MX use a multiplexed address and data bus to lower their pin count.
All the members of the Hobbit family operate at 3.3 V. The Hobbit architecture grew out of research by Bell Labs into processor architectures designed to run C programs as quickly as possible. Hobbit processors use high-speed context switching and interrupt response to support the unique needs of PDAs running multiple applic
ations and telecommunications.
Hobbit chip sets are designed to support the advanced communications features that you'll probably come to expect of a PDA. For example, support for AT&T's reprogrammable multimedia DSPs (digital signal processors) is built in, as is support for AT&T's DSP-based 3.3-V V.32lite PCMCIA data pump which, in turn, can support a high-speed fax or modem, two-way paging, or cellular connections.
AT&T is betting that the PDA future will look more like a telephone with a computer in it, and less like a small computer that can also fax and talk. It's a compelling bet, if only because the public is accustomed to small portable telephones and big stationary computers.
AT&T 92K Hobbit Family Processors
With the three 92020 processors, AT&T offers a wide range of solutions to PDA OEMs.
ATT92010 CHIP SET ATT92020S CHIP SET
Price (quantity 1000) $99 $152
Architectural enhancements
None Wait for interrupt,
6-KB prefetch buffer
Performance 13.5 MIPS 16 VAX MIPS
Performance/power 54 VAX MIPS/watt 76 VAX MIPS/watt
Power dissipation 250 mW (typical) 210 mW (typical)
Support controllers System: 92011 System: 92011
Display: 92014 Display: 92014
PCMCIA: 92012 PCMCIA: 92012
Peripheral: 92013
Display type LCD/CRT (21014)* LCD/CRT (21014)*
Maximum resolution 1024 by 768 (92014)* 1024 by 768 (92014)*
Gray levels 8+1 (92014)* 8+1 (92014)*
PCMCIA slots 4 (92012)* 4 (92012)*
P-ISA slots 8 (92013)* 0
ATT92020M CHIP SET ATT92020MX CHIP SET
Price (quan
tity 1000) $111 $76
Architectural enhancements Wait for interrupt, Wait for interrupt
6-KB prefetch buffer
Performance 13.5 VAX MIPS 11.5 VAX MIPS
Performance/power 54 VAX MIPS/watt 40 VAX MIPS/watt
Power dissipation 250 mW (typical) 290 mW (typical)
Support controllers System: 92021M System: 92021MX
Display: 92024M
Display type LCD/CRT (92024M)* LCD
Maximum resolution 1024 by 768 (92024M)* 640 by 480
Gray levels 16+1 (92024M)* 1+1
PCMCIA slots 2 1
P-ISA slots 0 0
* Support chip that supplies the indicated function
The AT&T Hobbit Enters Its Second Generation
