Date   : Fri, 07 Apr 1989 23:23:29 GMT
From   : mcvax!unido!cosmo!fifi%cosmo.UUCP@uunet.uu.net (A.F.Zinser)
Subject: Info: Z280 (was Re: New processor rumour)

In article <> beyer@frith.UUCP (Don W Beyer) writes:
> I agree, I won't believe it untill _I_ see it either!

The Z280 supports following types of multiplication/division:
- MULT A,r            - MULTU A,r
- MULTW HL,rr         - MULTUW HL,rr
- DIV HL,r            - DIVU HL,r
- DIVW DEHL,rr        - DIVUW DEHL,rr
  (DEHL => DE & HL taken as 32-bit-register)
where rr is one of
- BC, DE, HL, IX, IY, SP, nn, (nn), (IX+nn), (IY+nn), (PC+nn)
  (nn as a 2-byte-adress/offset)
and r is one of
- A, B, C, D, E, H, L, HX, LX, HY, LY, (HL), (nn), n, (HL+IX|IY),
  (IX+IY), (IX|IY+n), (IX|IY|HL|PC|SP+nn)
  (n as 1-byte-offset)

These new adressing-modes are supported in most commands (ADC, ADD,
AND (all type A,r), ADDW HL,rr, CP A,r, CPW HL,rr, DEC r|rr,
DECW rr, EX A,r, IN r,(C), INC{W} (see above), LD r|rr,r|rr (including
LD (nn),n, but not LD (nn),(nn)), LDW rr,rr (inc. LDW (nn),nn), OR A,r,
OUT (C),r, PUSH/POP rr (inc. PUSH/POP (nn) and PUSH/POP nn), rotation-
command in Z80-manner only, SBC/SUB A,r, SBC/SUBW HL,rr, XOR A,r)
and few new commands are implemented:
- DIV/MULT
- EPUM/EPUF/EPUI (for multi-processor-systems)
- MEPU (also mp-mode)
- PCACHE (cache clear)
- TSET r (test register contents and set flags)
- TSTI (C) (test input)
- LDCTL (for internal organisation/programming)
Important are the extended adressing-modes of CALL & JP:
- CALL cc,rr            - JP cc,rr
with cc as well-known from Z80 and rr on of following:
- (HL), (PC+nn), nn (CALL & JP)
- (IX), (IY) (JP only - like Z80)
Some other facts of Z280
- seperate memory- and i/o-wait-states, can be modified by software
- cache configurable as data- or instruction-cache (or both)
- 16-bit-i/o-adress supported
- single-step-mode
- user/system - mode
  (system-SP, user-SP)
But... the instruction-set may be a superset to that of the Z80,
one opcode differs from Z80 : TSET has the same opcode as SLIA
from Z80 (undocumented, but working). using this command, your
software is able to distinguish between Z280 and Z80.

axel f. zinser

[source: Zilog Z280 MPU - Technical Manual, March 1987]

(*) Z80, Z280 are registered trademarks of Zilog, Inc.

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|                      _     _                                            !
! Axel F. Zinser    (_!_) (_!_)    ...uunet!mcvax!unido!cosmo!fifi        |
| Hannover, BRD       !     !                      fifi@cosmo.UUCP        !
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