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+++
title = "IMC-2001 40 character mode"
+++
{{< figure src="/images/hardware/imc-2001/chargen.png" alt="character in the 40-char ROM" >}}
*A4-A6* on the schematics is the character ROM in a chip labelled
UMC UM2316-J127 8432, it is Intel 2716 EPROM compatible chip it seems.
It can be read with the TL866 and returns the following 2K dump:
[chargen.rom](/hardware/imc-2001/chargen.rom): Chargen 40-column ROM
The official ROM
[3410036.BIN](http://www.applelogic.org/APPLEASICs.html) on
http://www.applelogic.org/APPLEASICs.html doesn't match
at all. The arangement of the characters is different and there are
lowercase characters in the clone ROM.
I wrote a small program to show the contents of chargen.rom:
```
#!/usr/bin/tcc -run -Werror -DSDL_DISABLE_IMMINTRIN_H -I/usr/include/SDL2 -lSDL2
#include <stdio.h>
#include <stdlib.h>
#include <SDL.h>
int main( int argc, char *argv[] )
{
FILE *f = fopen( "./chargen.rom", "r" );
char *buf = malloc( 2 * 1024 );
fread( buf, 2 * 1024, 1, f );
SDL_Renderer *renderer;
SDL_Window *window;
SDL_Init( SDL_INIT_VIDEO );
SDL_CreateWindowAndRenderer( 300, 200, 0, &window, &renderer );
SDL_SetRenderDrawColor( renderer, 0, 0, 0, 0 );
SDL_RenderClear( renderer );
SDL_SetRenderDrawColor(renderer, 0xFF, 0xB0, 0, 255 );
int x = 0;
int y = 0;
for( int c = 0; c < 2 * 1024; c++ ) {
int v = buf[c] & 0x00ff;
for( int b = 0; b < 8; b++ ) {
if( v & 0x01 ) {
SDL_RenderDrawPoint( renderer, x, y );
}
v >>= 1;
x++;
}
x -= 8;
y += 1;
if( ( (c+1) % 128 ) == 0 ) {
x += 10;
y = 0;
}
}
SDL_RenderPresent( renderer );
int done = 0;
while( !done ) {
SDL_Event event;
SDL_PollEvent( &event );
switch( event.type ) {
case SDL_QUIT:
case SDL_KEYDOWN:
done = 1;
break;
}
}
SDL_DestroyRenderer( renderer );
SDL_DestroyWindow( window );
SDL_Quit( );
free( buf );
fclose( f );
return 0;
}
```
And indeed I get:
{{< figure src="/images/hardware/imc-2001/chargen.png" alt="character in the 40-char ROM" >}}
|
