 HD64180SY10 | |
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| Instruction set | 8080, 8085,Z80, NSC 800 |
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TheHD64180 is aZ80-based embeddedmicroprocessor developed byHitachi with an integratedmemory management unit (MMU) and on-chip peripherals.[1] It appeared in 1985.[2] The Hitachi HD64180 "Super Z80" was later licensed toZilog and sold by them as the Z64180 and with some enhancements as theZilog Z180.
The HD64180 has the following features:
The HD64180 has apipelined execution unit which processes most instructions in fewerclock cycles than theZ80. The most improved instruction group comprises the block instructions; for example those such as LDIR, CPIR, INIR and OTDR. This instruction type takes 21 transition states to execute per iteration; on the HD64180 it takes 14 t-states.
The on-chip DMAC makes block memory transfers possible at a rate faster than the LDIR/LDDR instructions.[4] The on-chip generator for wait states makes it possible to access too-slow hardware on a selective basis using a device filter, as is done for theTRS-80 Model 4's balky keyboard. The on-chip ASCI makes it possible to implement additionalRS-232 serial ports.[5]
The HD64180 will not execute the "undocumented" Z80 instructions, particularly the ones that access theindex registers IX and IY as 8-bit halves. The Hitachi CPU treats them asillegal instructions and accordingly executes the "illegal instruction trap" behavior of resetting the PC register to zero, which simulates acold restart by redirecting execution to the power-up location.
The Micromint SB180, SemiDisk Systems DT42CP/M computers, and Olivetti CWP 1 and ETV 210s videotypewriters (also running ROM-based CP/M 2.2) were based on the Hitachi HD64180. The XLR8er upgrade board for theTRS-80 Model 4 also used it.[6] On the Victor HC-90 and HC-95MSX2 computer, the HD64B180 was used for its turbo mode next to the regular Z80.[7][8]
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