951x > AMDAM9511ADC

Modified: March 11, 2005, 11:26 pm

Manufacturer:	AMD
Model:	AM9511ADC
Speed:	2MHz
Type:	9511
Data Code:	8030
Introduced:	1979
Transistors:
Package:	24CDIP
Process:	3 Micron
Architecture:	FPU
Used in:	CP/M, S-100, Others
Description:	. AMD also produced what is probably the first floating point "coprocessor" for microprocessors, the AMD 9511 "arithmetic circuit" (1979), which performed 32 bit (23 + 7 bit floating point) RPN- style operations (4 element stack) under CPU control - the 64-bit 9512 (1980) lacked the transcendental functions. It was based on a 16- bit ALU, performed add, subtract, multiply, and divide (plus sine and cosine), and while faster than software on microprocessors of the time (about 4X speedup over a 4MHz Z-80), it was much slower (at 200+ cycles for 32*32->32 bit multiply) than more modern math coprocessors are. It was used in some CP/M (Z-80) systems, and on a S-100 bus math card for NorthStar systems. Calculator circuits (such as the National Semiconductor MM57109 (1980), actually a 4-bit NS COP400 processor with floating point routines in ROM) were also sometimes used, with emulated keypresses sent to it and results read back, to simplify programming rather than for speed.