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Ithaca Audio Z80 CPU Card.
This was Ithaca Audio's (later known a Intersystems) first S-100 card.

IA Z80-1 CPU Board

The card was designed to be a drop in replacement for a 8080 CPU card in Altair and IMSAI computes. The card was sold as a kit.  It did have an onboard ROM allowing a monitor boot directly from the board.  It was a very clean design. Was very reliable and sold well.

The card had the following features:-

On board 2708 EPROM addressable to any 4K boundary above 32K
Power-on-jump to any 4K boundary above 32K, or the on-board 2708
A wait state may be added to any:
  •  M1 cycle
  •  Memory Request cycle
  •  On-board ROM cycle (for use at 4 MHz)
  •  Input cycle
  •  Output cycle
On-board run-stop flip-flop and optional generation of MEMORY WRITE allow front panel-less operation-
Selectable 10 addressing mode:
  • 8080 mode where peripheral address byte is duplicated on high and low order address bytes
  • Z-80 mode where the peripheral byte appears on the low order address, and the contents of the accumulator appears on the high order byte, allowing simultaneous I/O
DMA Grant tri-states all signals from the processor board
8224 clock generator provides 8080 look-alike
Clock l and Clock2 for the S-100 bus
The manual for this card can be downloaded here.


Other InterSystems S-100 Boards
64K Dynamic RAM    8K RAM   EPROM   IA-Display   FDC   IO-Card    Z80-Series-II    Z80
   ADDA Board   EPROM Burner 
FPB   256K Dynamic RAM   16-64K EPROM
  HDA   Z80-Series_III   6-SIO   EPROM Emulator   RTC Board 


This page was last modified on 03/27/2017