Nasbug T4  Extended 2K Monitor for Nascom I

Nasbug T4 incorporates the best facilities of Nasbug T2 and B-BUG, and has been further extended to allow keyboard access to the PORTS, use as an intelligent terminal, keyboard shift options, and the Z80 restarts to be of more use to the user.

Command Table

A

Hexadecimal arithmetic to calculate the sum, difference and relative jump of two addresses.

B

Breakpoint as Nasbug T2, but also automatically relocates the cursor to the bottom left of the screen if it has been moved by the user, Breakpoint is set to zero on Reset.

C

Copy as in Nasbug T2.

D

Dump as in Nasbug T2, but with extra features for error erradication.

E

Execute as in Nasbug T2.

G

Generate.   On reading a tape recorded in this format, the tape enters its own Read and Execute commands and automatically executes itself.

I

Intelligent Copy will copy data up or down without corruption which can occur under certain conditions using the C command. C command has been left in the command table as the corruption caused can be deliberately used to profit under certain conditions.

K

K0

Nascom keyboard as normal but shift now gives lower case letters. K0 is automatically set on RESET.

K1

Letters shift is inverted from K0 (typewriter mode).

K2

As K0, but holding down the space bar causes the ASCII representation of the character typed to be displayed.

K3

As K1 but in ASCII mode as K2.

L

Load as Nasbug T2.

M

Memory examine/​modify as Nasbug T2, but is additionally capable of backwards stepping through memory, and immediate jumps to different locations in memory.

N

Reverts ‘X’ to normal.

O

Output to a port.

Q

Input from a port.

R

Read as in B-BUG. Four times faster than ‘L’.

S

Single-step as Nasbug T2, but relocates cursor as in ‘B’ (above).

T

Tabulate as in Nasbug T2.

/ .. ..