GoVM

Specification

• 16-Bit address space (from 0x0000 to 0xFFFF)
• 8 registers
  • Operation registers (AX, BX, CX, DX)
  • Pointer registers (CP, SP)
  • Flag registers (ZF, CF)
• Interrupt pointers (IX)
  • On-Off interrupt
  • Keyboard interrupt
  • Stack overflow interrupt
• Big endian memory layout
• All standard operations supported
• Virtual console display (80x24 character grid, 16 colors)

Memory layout

0 - F

Address	Description	Name
0	code pointer	CP
2	stack pointer	SP
4	zero flag	ZF
6	carry flag	CF
8	register	AX
A	register	BX
C	register	CX
E	register	DX

10 - FF

Address	Description	Name
10	interrupt value	IX
12	ir state	IT
14	ir keyboard	IK
16	ir stack overflow	IS

100 - FFF

Address	Description	Name
100	stack base	SB
...	stack	-
FFF	stack max	-

1000 - 1FFFF

The memory layout of this region differs from mode to mode. The graphics mode is stored in 1FFE.

The only available mode at this time is the terminal mode (80x24). In this mode the region (1000 - 1EFF) stores character and color data. The first byte maps the color (first half foreground, second half background). You can choose between 8 different colors. The second byte must be a UTF-8 encoded character.

License

Copyright 2016 Lennart Espe. All rights reserved.

Use of this source code is governed by a MIT-style license that can be found in the LICENSE.md file.