AMD Am2900


Am2900 is a family of integrated circuits created in 1975 by Advanced Micro Devices. They were constructed with bipolar devices, in a bit-slice topology, and were designed to be used as modular components each representing a different aspect of a computer control unit. By using the bit slicing technique, the Am2900 family was able to implement a CCU with data, addresses, and instructions to be any multiple of four bits by multiplying the number of ICs. This requires more ICs to implement than what could be done on a single CPU IC, but at the time, the TTL Am2900 chips ran at 2040 MHz, which was much faster than the 23 MHz CMOS/NMOS microprocessors of the era such as the Intel 8085. 8085 emulators were implemented around two Am2900 chips which ran 5 to 10 times faster than the 8085-based designs they replaced.
The Am2901 chip included an arithmetic logic unit and 16 4-bit processor register slices, and was the "core" of the series. It could count using 4 bits and implement binary operations as well as various bit shifting operations. The Am2909 was a 4-bit-slice address sequencer that could generate 4-bit addresses on a single chip, and by using n of them, it was able to generate 4n-bit addresses. It had a stack that could store a microprogram counter up to four nest levels, as well as a stack pointer.
The Am2901 and some of the other chips in the family were second sourced by an unusually large number of other manufacturers, starting with Motorola and then Raytheon—both in 1975—and also Cypress Semiconductor, National Semiconductor, NEC, Thomson, and Signetics. In the Soviet Union and later Russia the Am2900 family was manufactured as the 1804 series which was known to be in production in 2016.

Computers made with Am2900-family chips

There are probably many more, but here are some known machines using these parts:

Members of the Am2900 family

The Am2900 Family Data Book lists:
  • Am2901 – 4-bit bit-slice ALU and processor register set
  • Am2902 – Look-Ahead Carry Generator
  • Am2903 – 4-bit-slice ALU, with hardware multiply
  • Am2904 – Status and Shift Control Unit
  • Am2905 – Bus Transceiver
  • Am2906 – Bus Transceiver with Parity
  • Am2907 – Bus Transceiver with Parity
  • Am2908 – Bus Transceiver with Parity
  • Am2909 – 4-bit-slice address sequencer
  • Am2910 – Microprogram Controller
  • Am2911 – 4-bit-slice address sequencer
  • Am2912 – Bus Transceiver
  • Am2913 – Priority Interrupt Expander
  • Am2914 – Priority Interrupt Controller
  • Am2915 – Quad 3-State Bus Transceiver
  • Am2916 – Quad 3-State Bus Transceiver
  • Am2917 – Quad 3-State Bus Transceiver
  • Am2918 – Instruction Register, Quad D Register
  • Am2919 – Instruction Register, Quad Register
  • Am2920 – Octal D-Type Flip-Flop
  • Am2921 – 1-to-8 Decoder
  • Am2922 – 8-Input Multiplexer
  • Am2923 – 8-Input MUX
  • Am2924 – 3-Line to 8-Line Decoder
  • Am2925 – System Clock Generator and Driver
  • Am2926 – Schottky 3-State Quad Bus Driver
  • Am2927/Am2928 – Quad 3-State Bus Transceiver
  • Am2929 – Schottky 3-State Quad Bus Driver
  • Am2930 – Main Memory Program Control
  • Am2932 – Main Memory Program Control
  • Am2940 – Direct Memory Addressing (DMA) Generator
  • Am2942 – Programmable Timer/Counter/DMA Generator
  • Am2946/Am2947 – Octal 3-State Bidirectional Bus Transceiver
  • Am2948/Am2949 – Octal 3-State Bidirectional Bus Transceiver
  • Am2950/Am2951 – 8-bit Bidirectional I/O Ports
  • Am2954/Am2955 – Octal Registers
  • Am2956/Am2957 – Octal Latches
  • Am2958/Am2959 – Octal Buffers/Line Drivers/Line Receivers
  • Am2960 – Cascadable 16-bit Error Detection and Correction Unit
  • Am2961/Am2962 – 4-bit Error Correction Multiple Bus Buffers
  • Am2964 – Dynamic Memory Controller
  • Am2965/Am2966 – Octal Dynamic Memory Driver
Many of these chips also have 7400 series numbers such as the 74F2960 / Am2960.