From Herb Johnson (
http://www.retrotechnology.com/
)
Looking at the data sheets only.....
1) Looks to me like the 2513 output enable pin 11 should be connected to the 2716 output enable pin 20. The 2716 also has a chip enable pin 18, I suggest it be grounded so the chip is always active.
2) More important - the 2716 has two additional address lines at pin 22 (A9) and pin 19 (A10). If you don't ground them, they will float high and you'll not address the bottom 1/4 of the ROM as you should. Worse, if they wriggle around and you get intermittent addressing.
3) Of course 2513 VCC at 24 goes to 2716 pin 24; 2513 ground pin 10 goes
to 2716 pin 12 and to ground other points. Wire the data outputs so the lowest five bits are wired through. A look at the binaries on the Web site as linked, shows only the lowest 5 bits are in use.
Data rates? Use a scope to see how fast the ROM address changes. Or do some math based on horizontal scan and chars across the screen but a scope is simpler. 15750 Hz X 80 char = 1.26MHz to read a char from the ROM per line. That's about 800ns, it's probably a little faster than that.
Looking at the data sheets only.....
1) Looks to me like the 2513 output enable pin 11 should be connected to the 2716 output enable pin 20. The 2716 also has a chip enable pin 18, I suggest it be grounded so the chip is always active.
2) More important - the 2716 has two additional address lines at pin 22 (A9) and pin 19 (A10). If you don't ground them, they will float high and you'll not address the bottom 1/4 of the ROM as you should. Worse, if they wriggle around and you get intermittent addressing.
3) Of course 2513 VCC at 24 goes to 2716 pin 24; 2513 ground pin 10 goes
to 2716 pin 12 and to ground other points. Wire the data outputs so the lowest five bits are wired through. A look at the binaries on the Web site as linked, shows only the lowest 5 bits are in use.
Data rates? Use a scope to see how fast the ROM address changes. Or do some math based on horizontal scan and chars across the screen but a scope is simpler. 15750 Hz X 80 char = 1.26MHz to read a char from the ROM per line. That's about 800ns, it's probably a little faster than that.