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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" >}}