6502 to 8501: new details

From: Daniele Gratteri (daniele_gratteri_at_inwind.it)
Date: 2002-02-20 18:29:00

Today, I found a bit of time for trying the board more accurately.
First, I have run the benchmark program:

1 T1 = TI

I think I have understood that the plus/4 has a TI "resident" variable that
continuously changes its value. The program assigns to the T1 variable the
TI one when the program starts, then prints T1 and TI, that are TI values of
start and finish of the program. By making TI - T1 is possible to compare
execution time of the program. Is my analysis correct?
If it is, the 7501 gives results of TI - T1 like 2424/2425. The 6502 to 8501
board gives 2426/2425. So, I think the substitute board is as fast as the
original CPU.

I spoke about a bug with the cursor: maybe it was the board non properly
seated, since now it is disappeared. Also, it was only into the BASIC
interpreter (into the word processor the INST DEL key always worked fine).

I tried the 1531 Datassette. I have written the benchmark program first with
the 7501 CPU, then saved it to tape and ran the tests. When I switched to
the "CPU module" and I gave a LOAD command... Well, sometimes the cassette
motor doesn't start at all, sometimes it starts but the Datassette doesn't
see the program and, after a while, it gives a


In fact, I wasn't able to read anything from the cassette. Instead, if I try
to SAVE somthing, the computer behaves like it successfully saves the
program. Then, if I install the 7501, I cannot read the program saved with
the CPU module...
So, it seems there are incompatibility issues between the CPU module and the

P.S. For Ruud
Are you fine? It's because I haven't read any comments from you, so I just
need to know if it's all ok.
 / ___|____   Daniele Gratteri, Italian Commodore and Amiga user  / /
| |   |___/   E-MAIL: daniele_gratteri@inwind.it                 / /
| |___|___\   URL: http://utenti.tripod.it/danielegratteri   \ \/ /
 \____|       IRC: FIAT1100D - ICQ: 53943994                  \/\/

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