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Intel SDK-85

The 1977 System Design Kit, running Intel's own monitor ROM on the same 8085 the simulator uses. Write a program and load it into the board's RAM, or key it in the way you would have had to. The hex keys, . and , can also be typed when the editor does not have focus. Read how to operate it.

Cheat sheet

Full documentation →

Every command ends with . (EXEC). , (NEXT) moves to the next location or register. Keys are read by the monitor's interrupt routine, so the board has to be running for one to do anything — and the buttons on this page send these very keys, so both ways of working are the same command running in ROM.

SUBST MEM

Read and write memory

Also on this page: Memory panel

SUBST MEM 2 0 0 0 ,: show the byte at 2000H
3 E ,: store 3EH, move to 2001H
,: leave it alone, move on
.: done

EXAM REG

Read and write the registers

Also on this page: Registers panel

EXAM REG A: show the accumulator
F F ,: store FFH, move to the next
.: done

GO

Run a program

Also on this page: Run on the board

GO 2 0 0 0 .: run from 2000H
GO .: carry on from where it stopped

SINGLE STEP

One instruction at a time

Also on this page: Single step

SINGLE STEP 2 0 0 0 ,: execute the instruction at 2000H
,: and the next one
.: done

EXAM REG keys

The keypad has no S, P or I, so digits stand in for them.

A A

B B

C C

D D

E E

F Flags

3 I mask

8 H

9 L

4 SP high

5 SP low

6 PC high

7 PC low

, walks them in order: A, B, C, D, E, F, I, H, L, SPH, SPL, PCH, PCL.

Machine controls

These are the board itself rather than a monitor command.

Power off / on: A power cycle: the ROM is as burned and RAM comes up empty.
RESET: The RESET key. Processor and peripherals restart; RAM is kept.
VECT INTR: Raises RST 7.5 to take control back from a running program.
Pause / Step: The simulator's, not the board's: they stop the 8085 itself, monitor included.

Memory map

Assemble with ORG 2000H, and finish with RST 1 to hand the board back to the monitor.

0000–07FF: Monitor ROM. Writes ignored.
1800–19FF: 8279 keyboard and display
2000–20BF: RAM — yours, 192 bytes
20C0–20FF: RAM — the monitor's stack and saved registers