MC6847T1
Comparison of the MC6847 and MC6847T1 using PRINT CHR$ and direct screen pokes in a loop while in upper and lower code mode.1)
| VDG / MODE | PRINT CHR$ | SCREEN RAM POKE |
|---|---|---|
| MC6847 |  |  |
| MC6847T1 Uppercase |  |  |
| MC6847T1 Lowercase |  |  |
PRINT CHR$ LOOP
Simple print chr$ loop:
10 CLS(0) 20 FOR I=0 TO 255 30 PRINT CHR$(I); 40 NEXT 50 GOTO 50
SCREEN POKE LOOP
Simple loop to poke values 0-255 directly into screen RAM:
10 CLS(0) 20 FOR I=0 TO 255 30 POKE 1024+I, I 40 NEXT 50 GOTO 50
MC6847T1 LOWER CASE MODE
Put the MC6847T1 into lower case mode:
1 'http://www.retrogamingtimes.com/magazine/?issue=103&page=203&theme=christmas 10 POKE &H0167,&H39:'put RTS into RVEC3 to skip JMP to CONSOLE OUT 20 POKE &HFF22,&H50:'PIA2 VDG Control - switch in lower with green border
COMPATIBLE SOFTWARE
- Color File II
- Color Scripsit II
- Scott Adams adventure games
- OS-9 Level 1 version 2 I believe did (using XMODE)…
- NitrOS-9 level 1 for sure does.
- Both Mikeyterm and Greg-E-Term did as well.
RTS
Return to Tandy Color Computer
1)
Also note that the MC6847 and MC6847T1 character bitmap drawing has subtle differences. In particular, note the hash mark and asterisk differences between MC6847 and T1 version.